It is not known how the Pacific hagfish (Eptatretus stoutii) can survive extended periods of anoxia. The present study used two experimental approaches to examine energy use during and following anoxic exposure periods of different durations (6, 24 and 36 h). By measuring oxygen consumption prior to anoxic exposure, we detected a circadian rhythm, with hagfish being active during night and showing a minimum routine oxygen consumption (RMR) during the daytime. By measuring the excess post-anoxic oxygen consumption (EPAOC) after 6 and 24 h it was possible to mathematically account for RMR being maintained even though heme stores of oxygen would have been depleted by the animal’s metabolism during the first hours of anoxia. However, EPAOC after 36 h of anoxia could not account for RMR being maintained. Measurements of tissue glycogen disappearance and lactate appearance during anoxia showed that the degree of glycolysis and the timing of its activation varied among tissues. Yet, neither measurement could account for the RMR being maintained during even the 6-h anoxic period. Therefore, two independent analyses of the metabolic responses of hagfish to anoxia exposure suggest that hagfish utilize metabolic rate suppression as part of the strategy for longer-term anoxia survival.
Rainbow trout Oncorhynchus mykiss consume less energy when swimming near obstructions.
The effect of obstructions in steady flow on swimming by rainbow trout Oncorhynchus mykiss was examined in a respirometry swim tunnel to test the prediction that fish interacting with obstructions require less energy to hold station. When an obstruction was present, O. mykiss altered the kinematics of swimming and the rate of oxygen consumption was significantly reduced. The fish employed both entrainment and Kármán gait swimming strategies, permitting greater locomotor efficiency.
Partition of aerobic and anaerobic swimming costs related to gait transitions in a labriform swimmer.
Members of the family Embiotocidae exhibit a distinct gait transition from exclusively pectoral fin oscillation to combined pectoral and caudal fin propulsion with increasing swimming speed. The pectoral–caudal gait transition occurs at a threshold speed termed Up–c. The objective of this study was to partition aerobic and anaerobic swimming costs at speeds below and above the Up–c in the striped surfperch Embiotoca lateralis using swimming respirometry and video analysis to test the hypothesis that the gait transition marks the switch from aerobic to anaerobic power output. Exercise oxygen consumption rate was measured at 1.4, 1.9 and 2.3 L s–1. The presence and magnitude of excess post-exercise oxygen consumption (EPOC) were evaluated after each swimming speed. The data demonstrated that 1.4 L s–1 was below the Up–c, whereas 1.9 and 2.3 L s–1 were above the Up–c. These last two swimming speeds included caudal fin propulsion in a mostly steady and unsteady (burst-assisted) mode, respectively. There was no evidence of EPOC after swimming at 1.4 and 1.9 L s–1, indicating that the pectoral–caudal gait transition was not a threshold for anaerobic metabolism. At 2.3 L s–1, E. lateralis switched to an unsteady burst and flap gait. This swimming speed resulted in EPOC, suggesting that anaerobic metabolism constituted 25% of the total costs. Burst activity correlated positively with the magnitude of the EPOC. Collectively, these data indicate that steady axial propulsion does not lead to EPOC whereas transition to burst-assisted swimming above Up–c is associated with anaerobic metabolism in this labriform swimmer.
Female sticklebacks transfer information via eggs: effects of maternal experience with predators on offspring.
There is growing evidence that maternal experience influences offspring via non-genetic mechanisms. When female three-spined sticklebacks ( Gasterosteus aculeatus ) were exposed to the threat of predation, they produced larger eggs with higher cortisol content, which consumed more oxygen shortly after fertilization compared with a control group. As juveniles, the offspring of predator-exposed mothers exhibited tighter shoaling behaviour, an antipredator defence. We did not detect an effect of maternal exposure to predation risk on the somatic growth of fry. Altogether, we found that exposure to an ecologically relevant stressor during egg formation had several long-lasting consequences for offspring, some of which might be mediated by exposure to maternally derived cortisol. These results support the hypothesis that female sticklebacks might influence the development, growth and behaviour of their offspring via eggs to match their future environment.
Adaptation versus Allometry: Population and Body Mass Effects on Hypoxic Metabolism in Fundulus grandis.
Hypoxia has significant effects on organisms, from metabolic reduction to death, and could be an important evolutionary force affecting the variation among populations within a species. To determine intraspecific variation in hypoxic metabolism and the effect of body mass, we examine rates of oxygen consumption (M(O2)) at seven oxygen concentrations among seven populations of Fundulus grandis that inhabit a mosaic of habitats with different frequencies and intensities of hypoxia. For M(O2), there is a significant interaction (P< 0.05) between body mass and oxygen concentrations: log(10) body mass: log(10) M(O2) slopes were steeper at intermediate oxygen partial pressures (Po(2)) than either normoxic or lowest Po(2) (ANCOVA, P<0.001). Additionally, the PO(2crit) (Po(2) where M(O2) can no longer be maintained) was a negative function of body mass (P < 0.04). At the lowest Po(2) (1.8 kPa), there was a significant difference in M(O2) among populations: one of the populations from environments more frequently stressed by hypoxia has greater M(O2) at the lowest oxygen concentrations. With few differences among populations, the most important effects were how body mass affected M(O2) at intermediate Po(2) and the negative relationship between body mass and PO(2crit). These findings suggest that an increase in body size is a useful strategy to minimize the effect of hypoxia.
Do zebrafish Rh proteins act as dual ammonia-CO2 channels?
Most teleost fish reduce heart rate when exposed to acute hypoxia. This hypoxic bradycardia has been characterised for many fish species, but it remains uncertain whether this reflex contributes to the maintenance of oxygen uptake in hypoxia. Here we describe the effects of inhibiting the bradycardia on oxygen consumption (MO2), standard metabolic rate (SMR) and the critical oxygen partial pressure for regulation of SMR in hypoxia (Pcrit) in European eels Anguilla anguilla (mean ± SEM mass 528 ± 36 g; n = 14). Eels were instrumented with a Transonic flow probe around the ventral aorta to measure cardiac output (Q) and heart rate (f H). MO2 was then measured by intermittent closed respirometry during sequential exposure to various levels of increasing hypoxia, to determine Pcrit. Each fish was studied before and after abolition of reflex bradycardia by intraperitoneal injection of the muscarinic antagonist atropine (5 mg kg−1). In the untreated eels, f H fell from 39.0 ± 4.3 min−1 in normoxia to 14.8 ± 5.2 min−1 at the deepest level of hypoxia (2 kPa), and this was associated with a decline in Q, from 7.5 ± 0.8 mL min−1 kg−1 to 3.3 ± 0.7 mL min−1 kg−1 in normoxia versus deepest hypoxia, respectively. Atropine had no effect on SMR, which was 16.0 ± 1.8 μmol O2 kg−1 min−1 in control versus 16.8 ± 0.8 μmol O2 kg−1 min−1 following treatment with atropine. Atropine also had no significant effect on normoxic f H or Q in the eel, but completely abolished the bradycardia and associated decline in Q during progressive hypoxia. This pharmacological inhibition of the cardiac responses to hypoxia was, however, without affect on Pcrit, which was 11.7 ± 1.3 versus 12.5 ± 1.5 kPa in control versus atropinised eels, respectively. These results indicate, therefore, that reflex bradycardia does not contribute to maintenance of MO2 and regulation of SMR by the European eel in hypoxia.
The metabolic and biochemical basis of vulnerability to recreational angling after three generations of angling-induced selection in a teleost fish.
Although the selective pressures of commercial fishing are well known, few studies have examined this phenomenon in recreational fisheries. This study used a unique population of largemouth bass ( Micropterus salmoides ) with lines bred for low (LVF) and high (HVF) vulnerability to recreational angling. We evaluated whether differential vulnerability to angling was correlated with physiological traits, including metabolic rate, metabolic scope, anaerobic capacity, and biochemical response to exercise. Indeed, angling selection affected the metabolic rate of fish significantly. The standard metabolic rate was 10%, maximal metabolic rate was 14%, and metabolic scope was 16% lower for LVF compared with HVF. Following exhaustive exercise, LVF required 1 h for lactate levels to recover to control values, whereas HVF required 2 h. Anaerobic energy expenditure was significantly lower for LVF, a finding consistent with the observation that LVF swam at a steadier rate during exercise. Although the reasons behind vulnerability to angling are complex, the phenotypic trait “vulnerability to angling” appears to be linked to a suite of physiological traits, including metabolism and the capacity for anaerobic activity. Thus, angling-induced selection might alter the physiological characteristics of wild largemouth bass populations, with unknown outcomes for long-term population viability.
Salinity selection and preference of the grey snapper Lutjanus griseus: field and laboratory observations.
Field observations were supplemented with laboratory experiments to reveal patterns of salinity selection and preference for grey snapper Lutjanus griseus ( c. 21 cm total length, L T ), an ecologically and economically important species in the south‐eastern U.S.A. Fish abundance data were examined from a long‐term field survey conducted in the mangrove habitats of Biscayne Bay, Florida, where salinities ranged from <1 to 40. First, regression analyses indicated significant, positive linear relationships with salinity for both L. griseus frequency of occurrence and concentration (density when present). These patterns are inconsistent with physiological expectations of minimizing energetic osmoregulatory costs. Next, the salinity preference and swimming activity of 11 L. griseus (ranging from 18 to 23 cm L T ) were investigated using a newly developed electronic shuttlebox system. In the laboratory, fish preferred intermediate salinities in the range of 9–23. Swimming activity (measured in terms of spontaneous swimming speed) followed a parabolic relationship with salinity, with reduced activity at salinity extremes perhaps reflecting compensation for higher osmoregulatory costs. It is suspected that the basis of the discrepancy between laboratory and field observations for size classes at or near maturity ultimately relates to the reproductive imperative to move towards offshore (high‐salinity) coral‐reef habitats, a necessity that probably overrides the strategy of minimizing osmoregulatory energetic costs.
The effects of swimming pattern on the energy use of gilthead seabream (Sparus aurata L.)
Oxygen consumption (MO2) was measured for gilthead seabream (Sparus aurata) during spontaneous and forced activities. During spontaneous activity, the swimming pattern was analysed for the effect on MO2 on the average speed (U), turning rate ( ) and change in speed (DU). All swimming characteristics contributed significantly to the source of spontaneous swimming costs, and the models explained up to 58 % of the variation in
Swimming performance and associated ionic disturbance of juvenile pink salmon Oncorhynchus gorbuscha determined using different acceleration profiles
Swimming performance was assessed in juvenile pink salmon Oncorhynchus gorbuscha (body mass <5·0 g) using five different protocols: four constant acceleration tests each with a different acceleration profile (rates of 0·005, 0·011, 0·021 and 0·053 cm s −2 ) and a repeated ramped‐critical swimming speed test. Regardless of the swim protocol, the final swimming speeds did not differ significantly ( P > 0·05) among swim tests and ranged from 4·54 to 5·20 body lengths s −1. This result supports the hypothesis that at an early life stage, O. gorbuscha display the same fatigue speeds independent of the swimming test utilized. Whole body and plasma [Na + ] and [Cl − ] measured at the conclusion of these tests were significantly elevated when compared with control values ( P < 0·05) and appear to be predominantly associated with dehydration rather than net ion gain. Given this finding for a small salmonid, estimates of swim performance can be accurately measured with acceleration tests lasting <10 min, allowing a more rapid processing than is possible with a longer critical swim speed test.
Behaviour and performance of juvenile shortnose sturgeon Acipenser brevirostrum at different water velocities.
Critical swimming speeds (mean ± s. e.) for juvenile shortnose sturgeon Acipenser brevirostrum were 34·4 cm s −1 ± 1·7 (2·18 ± 0·09 body lengths, BL s −1 ). Swimming challenges at 10, 20 and 30 cm s −1 revealed that juvenile A. brevirostrum are relatively poor swimmers, and that the fish did not significantly modify their swimming behaviour, although they spent more time substratum skimming ( i.e. contact with flume floor) at 30 cm s −1 relative to 10 cm s −1. When present, these behavioural responses are probably related to morphological features, such as flattened rostrum, large pectoral fins, flattened body shape and heterocercal tail, and may be important to reduce the costs of swimming.
The intestinal response to feeding in seawater gulf toadfish, Opsanus beta, includes elevated base secretion and increased epithelial oxygen consumption.
Intestinal HCO3− secretion is essential to marine teleost fish osmoregulation and comprises a considerable source of base efflux attributable to both serosal HCO3− and endogenous CO2 hydration. The role of intestinal HCO3− secretion in dynamic acid—base balance regulation appears negligible in studies of unfed fish, but evidence of high intestinal fluid [HCO3−] in fed marine teleosts led us to investigate the source of this HCO3− and its potential role in offsetting the postprandial ‘alkaline tide’ commonly associated with digestion. Specifically, we hypothesized that elevated metabolic rate and thus endogenous CO2 production by intestinal tissue as well as increased transepithelial intestinal HCO3− secretion occur post-feeding and offset a postprandial alkaline tide. To test these hypotheses changes in HCO3− secretion and O2 consumption by gulf toadfish (Opsanus beta) isolated intestine were quantified 0, 3, 6, 12, 24 and 48 h post-feeding. Intestinal tissue of unfed fish in general showed high rates of HCO3− secretion (15.5 μmol g−1 h−1) and O2 consumption (8.9 μmol g−1 h−1). Furthermore, postprandial increases in both intestinal HCO3− secretion and O2 consumption (1.6- and 1.9-fold peak increases, respectively) were observed. Elevated intestinal HCO3− secretion rates preceded and outlasted those of O2 consumption, and occurred at a magnitude and duration sufficient to account for the lack of alkaline tide. The dependence of these high rates of postprandial intestinal base secretion on serosal HCO3− indicates transepithelial HCO3− transport increases disproportionately more than endogenous CO2 production. The magnitude of postprandial intestinal HCO3− secretion indicates the intestine certainly is capable of postprandial acid#x02014;base balance regulation.
Carbonic anhydrase expression and CO2 excretion during early development in zebrafish Danio rerio.
Carbonic anhydrase (CA) is critical for CO2 excretion in adult fish, but little is known of the expression or function of CA during early development. The present study examined the hypothesis that, as rates of CO2 production increased during early development in zebrafish (Danio rerio), CA would become necessary for effective CO2 excretion, and that the pattern of CA expression during early development would reflect this transition. Real-time RT-PCR was used to examine the mRNA expression of the two main intracellular CA isoforms over a time course of early development ranging from 0 to 120 h post fertilization (h.p.f.). The mRNA expression of zCAb was generally higher than that of zCAc, particularly during the earliest stages of development. Rates of CO2 excretion increased approximately 15-fold from 24 to 48 h.p.f. whereas rates of O2 uptake increased only 6.7-fold over the same period, indicating a relative stimulation of CO2 excretion over O2 uptake. Treatment of 48 h.p.f. larvae with the CA inhibitor acetazolamide resulted in CO2 excretion rates that were 52% of the value in control larvae, a significant difference that occurred in the absence of any effect on O2 uptake. Antisense morpholino oligonucleotides were used to selectively knock down one or both of the main intracellular CA isoforms. Subsequent measurement of gas transfer rates at 48 h.p.f. indicated that CA knockdown caused a significant relative inhibition of CO2 excretion over O2 uptake, regardless of which cytosolic CA isoform was targeted for knockdown. These results suggest that between 24 h.p.f. and 48 h.p.f., developing zebrafish begin to rely on CA to meet requirements for increased CO2 excretion.
Respiratory and digestive responses of postprandial Dungeness crabs, Cancer magister, and blue crabs, Callinectes sapidus, during hyposaline exposure.
Respiratory responses and gastric processing were examined during hyposaline exposure in two crab species of differing osmoregulatory ability. The efficient osmoregulator, Callinectes sapidus, displayed an immediate increase in oxygen uptake when exposed to low salinity in isolation. In contrast, the weak osmoregulator, Cancer magister, showed no change in oxygen uptake upon acute exposure (<6 h), but slight increases in oxygen uptake tended to occur over longer time scales (12–24 h). These changes were likely attributable to an increase in avoidance activity after 6 h hyposaline exposure. Following feeding in 100% SW, oxygen uptake doubled for both species and remained elevated for 15 h. When postprandial crabs were exposed to low salinities, C. sapidus were able to sum the demands of osmoregulation and digestion. Thus, gastric processes continued unabated in low salinity. Conversely, postprandial C. magister prioritized responses to low salinity over those of digestion, resulting in a decrease in oxygen uptake when exposed to low salinity. This decrease in oxygen uptake corresponded to a reduction in the rate of contraction of the pyloric stomach and a subsequent doubling of gastric evacuation time. The current study is one of the few to illustrate how summation or prioritization of competing physiological systems is manifested in digestive processes.
Effects of nutritional status on metabolic rate, exercise and recovery in a freshwater fish.
The influence of feeding on swimming performance and exercise recovery in fish is poorly understood. Examining swimming behavior and physiological status following periods of feeding and fasting is important because wild fish often face periods of starvation. In the current study, researchers force fed and fasted groups of largemouth bass (Micropterus salmoides) of similar sizes for a period of 16 days. Following this feeding and fasting period, fish were exercised for 60 s and monitored for swimming performance and physiological recovery. Resting metabolic rates were also determined. Fasted fish lost an average of 16 g (nearly 12%) of body mass, while force fed fish maintained body mass. Force fed fish swam 28% further and required nearly 14 s longer to tire during exercise. However, only some physiological conditions differed between feeding groups. Resting muscle glycogen concentrations was twofold greater in force fed fish, at rest and throughout recovery, although it decreased in both feeding treatments following exercise. Liver mass was nearly three times greater in force fed fish, and fasted fish had an average of 65% more cortisol throughout recovery. Similar recovery rates of most physiological responses were observed despite force fed fish having a metabolic rate 75% greater than fasted fish. Results are discussed as they relate to largemouth bass starvation in wild systems and how these physiological differences might be important in an evolutionary context.
The energetic costs of alternative male reproductive strategies in Xiphophorus nigrensis.
The coexistence of alternative male mating strategies depends on the balance between costs and benefits. Here we examine the short-term metabolic costs associated with distinct reproductive strategies in the genetically determined alternative male phenotypes of a northern swordtail, Xiphophorus nigrensis. In this species, large males court females, non-adorned small males chase females, and intermediate males exhibit both courtship and chase behaviors. Using intermittent flow respirometry, we measure oxygen consumption rates and behaviors of each size class in isolation and in the presence of a female. Changes in oxygen consumption between solitary and female presence trials (ΔVO2) correlated significantly with standard length across all size classes (r = 0.42). Only the large male class exhibited a significant increase in oxygen consumption in female-present trials exhibiting a range of increase from 2 to 200% relative to solitary metabolic rates, but costs of specific courtship displays could not be demonstrated. Sword length explained 54–57% of the variation in oxygen consumption in large male solitary trials and 63–65% in the female-present trials independent of any behavioral correlation with sword length. Our results exhibit similarities to condition-dependent alternative mating systems where the female-favored phenotype has higher energetic costs.
Physiological responses of postprandial red rock crabs (Cancer productus) during emersion.
The physiological responses of unfed and postprandial red rock crabs ( Cancer productus J.W. Randal, 1840) were investigated during periods of emersion. During aerial exposure, oxygen uptake quickly fell to very low levels and was no longer detectable in the haemolymph after 12 h. The resulting anaerobic respiration led to a build up in lactic acid and the resulting acidosis was more pronounced in the postprandial crabs. There was also a concomitant rise in PCO 2 and CCO 2, and in both cases these were higher in postprandial animals. Higher ammonia levels in postprandial crabs showed that cellular activities were still proceeding anaerobically, suggesting that although crabs can delay mechanical digestion during emersion, once intracellular digestion occurs they may be committed to these processes. Increased mortality rates of postprandial animals were probably due to a combination of the high lactate and CO 2 levels coupled with an increased ammonia concentration. For C. productus stranded in the intertidal zone there may be little effect of feeding, as they are only exposed for short periods and recovery occurs during re-immersion. The crabs are more likely to become moribund and death ensue during longer term exposure such as commercial live shipment.
Pectoral fin beat frequency predicts oxygen consumption during spontaneous activity in a labriform swimming fish ( Embiotoca lateralis ).
The objective of this study was to identify kinematic variables correlated with oxygen consumption during spontaneous labriform swimming. Kinematic variables (swimming speed, change of speed, turning angle, turning rate, turning radius and pectoral fin beat frequency) and oxygen consumption (MO2) of spontaneous swimming in Embiotoca lateralis were measured in a circular arena using video tracking and respirometry, respectively. The main variable influencing MO2 was pectoral fin beat frequency (r 2 = 0.71). No significant relationship was found between swimming speed and pectoral fin beat frequency. Complementary to other methods within biotelemetry such as EMG it is suggested that such correlations of pectoral fin beat frequency may be used to measure the energy requirements of labriform swimming fish such as E. lateralis in the field, but need to be taken with great caution since movement and oxygen consumption patterns are likely to be quite different in field situation compared to a small lab tank. In addition, our methods could be useful to measure metabolic costs of growth and development, or bioassays for possible toxicological effects on fish.
Effects of dietary restriction on mortality and age-related phenotypes in the short-lived fish Nothobranchius furzeri.
The short‐lived annual fish Nothobranchius furzeri shows extremely short captive life span and accelerated expression of age markers, making it an interesting model system to investigate the effects of experimental manipulations on longevity and age‐related pathologies. Here, we tested the effects of dietary restriction (DR) on mortality and age‐related markers in N. furzeri. DR was induced by every other day feeding and the treatment was performed both in an inbred laboratory line and a longer‐lived wild‐derived line. In the inbred laboratory line, DR reduced age‐related risk and prolonged maximum life span. In the wild‐derived line, DR induced early mortality, did not reduce general age‐related risk and caused a small but significant extension of maximum life span. Analysis of age‐dependent mortality revealed that DR reduced demographic rate of aging, but increased baseline mortality in the wild‐derived strain. In both inbred‐ and wild‐derived lines, DR prevented the expression of the age markers lipofuscin in the liver and Fluoro‐Jade B (neurodegeneration) in the brain. DR also improved performance in a learning test based on conditioning (active avoidance in a shuttle box). Finally, DR induced a paradoxical up‐regulation of glial fibrillary acidic protein in the brain.
Hypoxia-Induced Retinal Angiogenesis in Zebrafish as a Model to Study Retinopathy.
Mechanistic understanding and defining novel therapeutic targets of diabetic retinopathy and age-related macular degeneration (AMD) have been hampered by a lack of appropriate adult animal models. Here we describe a simple and highly reproducible adult fli-EGFP transgenic zebrafish model to study retinal angiogenesis. The retinal vasculature in the adult zebrafish is highly organized and hypoxia-induced neovascularization occurs in a predictable area of capillary plexuses. New retinal vessels and vascular sprouts can be accurately measured and quantified. Orally active anti-VEGF agents including sunitinib and ZM323881 effectively block hypoxia-induced retinal neovascularization. Intriguingly, blockage of the Notch signaling pathway by the inhibitor DAPT under hypoxia, results in a high density of arterial sprouting in all optical arteries. The Notch suppression-induced arterial sprouting is dependent on tissue hypoxia. However, in the presence of DAPT substantial endothelial tip cell formation was detected only in optic capillary plexuses under normoxia. These findings suggest that hypoxia shifts the vascular targets of Notch inhibitors. Our findings for the first time show a clinically relevant retinal angiogenesis model in adult zebrafish, which might serve as a platform for studying mechanisms of retinal angiogenesis, for defining novel therapeutic targets, and for screening of novel antiangiogenic drugs.
Phototoxicity of pyrene affects benthic algae and bacteria from the Arctic.
Phototoxicity of polycyclic aromatic hydrocarbons (PAHs) in the Arctic is important to study since the future PAH load is likely to increase. In combination with the increased UV-light penetration due to ozone layer thinning, phototoxicity may be a potential problem for arctic areas. The aim of this study was to evaluate effects of pyrene and phototoxicity of pyrene on natural algae and bacteria from arctic sediments. Sediments from a shallow-water marine baywere spiked with different pyrene concentrations. Microcosms containing the sediment were incubated under three light regimes, natural sunlight with UV-light, natural sunlight without UV-light, and dark. Significant effects were evident at low pyrene concentrations, particularly in presence of UV-light, indicating phototoxicity. The microalgae were especially sensitive to the phototoxicity of pyrene. Already atthe lowest pyrene concentration (Cfree: 4 nM) algal 14C-incorporation and chlorophyll a content were reduced. The toxic effects of pyrene on the microalgae probably led to the release of organic matter. In agreement with this, bacterial activity increased at high pyrene concentrations indicated by increased oxygen consumption and increased release of inorganic N and P from the sediment. This study indicates that phototoxicity of PAHs may be relevant for sediment communities from shallow marine arctic areas at environmentally relevant pyrene concentrations.
The effect of acute hypoxia on swimming stamina at optimal swimming speed in flathead grey mullet Mugil cephalus.
Flathead grey mullets Mugil cephalus are commonly found in Mediterranean lagoons, which are regularly subject to high environmental variations. Oxygen is one of the factors that shows extremely high variation. The objective of this study was to test the effects of acute hypoxia exposure at two experimental temperatures (i.e. 20 and 30°C) on the stamina (time to fatigue) in M. cephalus swimming at the minimal cost of transport (i.e. optimal swimming speed; Uopt). At each temperature, a relationship was established between swimming speed and oxygen consumption (MO2). This allowed estimation of Uopt at 45 cm s−1 (~1.12 Body Length s−1). Independent of temperature, stamina at Uopt was significantly reduced in severe hypoxia, i.e. at 15% of air saturation (AS). In these conditions, oxygen supply appears therefore to be insufficient to maintain swimming, even at the low speed tested here. After the stamina test, MO2 measured in fish tested at 15% AS was significantly higher than that measured after the test in normoxia. Therefore, we suggest that in hypoxia, fish used anaerobic metabolism to supplement swimming at Uopt, leading to an oxygen debt. Since flathead grey mullet is a hypoxia-tolerant species, it is possible that hypoxic conditions less severe than those tested here may reduce stamina at low speed in less tolerant species. In addition, we suggest that testing stamina at these speeds may be relevant in order to understand the effect of hypoxia on behavioural activities carried out at low speed, such as food searching.
The effects of acute temperature change on swimming performance in bluegill sunfish Lepomis macrochirus.
Many fish change gait within their aerobically supported range of swimming speeds. The effects of acute temperature change on this type of locomotor behavior are poorly understood. Bluegill sunfish swim in the labriform mode at low speeds and switch to undulatory swimming as their swimming speed increases. Maximum aerobic swimming speed (Umax),labriform-undulatory gait transition speed (Utrans) and the relationships between fin beat frequency and speed were measured at 14,18, 22, 26 and 30°C in bluegill acclimated to 22°C. At temperatures below the acclimation temperature (Ta), Umax, Utrans and the caudal and pectoral fin beat frequencies at these speeds were reduced relative to the acclimation level. At temperatures above Ta there was no change in these variables relative to the acclimation level. Supplementation of oxygen levels at 30°C had no effect on swimming performance. The mechanical power output of the abductor superficialis, a pectoral fin abductor muscle, was measured in vitro at the same temperatures used for the swimming experiments. At and below Ta, maximal power output was produced at a cycle frequency approximately matching the in vivo pectoral fin beat frequency. At temperatures above Ta muscle power output and cycle frequency could be increased above the in vivo levels at Utrans. Our data suggest that the factors triggering the labriform–undulatory gait transition change with temperature. Muscle mechanical performance limited labriform swimming speed at Ta and below, but other mechanical or energetic factors limited labriform swimming speed at temperatures above Ta.
Synergistic effects of climate-related variables suggest future physiological impairment in a top oceanic predator.
By the end of this century, anthropogenic carbon dioxide (CO 2 ) emissions are expected to decrease the surface ocean pH by as much as 0.3 unit. At the same time, the ocean is expected to warm with an associated expansion of the oxygen minimum layer (OML). Thus, there is a growing demand to understand the response of the marine biota to these global changes. We show that ocean acidification will substantially depress metabolic rates (31%) and activity levels (45%) in the jumbo squid, Dosidicus gigas, a top predator in the Eastern Pacific. This effect is exacerbated by high temperature. Reduced aerobic and locomotory scope in warm, high-CO 2 surface waters will presumably impair predator–prey interactions with cascading consequences for growth, reproduction, and survival. Moreover, as the OML shoals, squids will have to retreat to these shallower, less hospitable, waters at night to feed and repay any oxygen debt that accumulates during their diel vertical migration into the OML. Thus, we demonstrate that, in the absence of adaptation or horizontal migration, the synergism between ocean acidification, global warming, and expanding hypoxia will compress the habitable depth range of the species. These interactions may ultimately define the long-term fate of this commercially and ecologically important predator.
Essential fatty acids influence metabolic rate and tolerance of hypoxia in Dover sole (Solea solea) larvae and juveniles.
Dover sole (Solea solea, Linneaus 1758) were raised from first feeding on brine shrimp (Artemia sp.) with different contents and compositions of the essential fatty acids (EFA) arachidonic acid (ARA, 20:4n − 6); eicosapentaenoic acid (EPA, 20:5n − 3), and docosahexaenoic acid (DHA, 22:6n − 3), and their metabolic rate and tolerance to hypoxia measured prior to and following metamorphosis and settlement. Four dietary Artemia preparations were compared: (1) un-enriched; (2) enriched with a commercial EFA mixture (Easy DHA SELCO Emulsion); (3) enriched with a marine fish oil combination (VEVODAR and Incromega DHA) to provide a high ratio of ARA to DHA, and (4) enriched with these fish oils to provide a low ratio of ARA to DHA. Sole fed un-enriched Artemia were significantly less tolerant to hypoxia than the other dietary groups. Larvae from this group had significantly higher routine metabolic rate (RMR) in normoxia, and significantly higher O2 partial pressure (PO2) thresholds in progressive hypoxia for their regulation of RMR (Pcrit) and for the onset of agitation, respiratory distress and loss of equilibrium. Metamorphosis was associated with an overall decline in RMR and increase in Pcrit, but juveniles fed on un-enriched Artemia still exhibited higher Pcrit and agitation thresholds than the other groups. Sole fed un-enriched Artemia had significantly lower contents of EFA in their tissues, both before and after settlement. Thus, enriching live feeds with EFA has significant effects on the respiratory physiology of sole early life stages and improves their in vivo tolerance to hypoxia. We found no evidence, however, for any effect of the ratio of ARA to DHA.
Behavioural phenotype affects social interactions in an animal network.
Animal social networks can be extremely complex and are characterized by highly non-random interactions between group members. However, very little is known about the underlying factors affecting interaction preferences, and hence network structure. One possibility is that behavioural differences between individuals, such as how bold or shy they are, can affect the frequency and distribution of their interactions within a network. We tested this using individually marked three-spined sticklebacks ( Gasterosteus aculeatus ), and found that bold individuals had fewer overall interactions than shy fish, but tended to distribute their interactions more evenly across all group members. Shy fish, on the other hand, tended to associate preferentially with a small number of other group members, leading to a highly skewed distribution of interactions. This was mediated by the reduced tendency of shy fish to move to a new location within the tank when they were interacting with another individual; bold fish showed no such tendency and were equally likely to move irrespective of whether they were interacting or not. The results show that animal social network structure can be affected by the behavioural composition of group members and have important implications for understanding the spread of information and disease in social groups.
Can pikeperch colonise new freshwater systems via estuaries? Evidence from behavioural salinity tests.
Pikeperch (Sander lucioperca) are non-native in the United Kingdom. It is important to understand how environmental factors, such as salinity, influence the behaviour and activity of introduced fish species to identify their dispersal potential. Previous studies have shown that pikeperch, traditionally recognised as a freshwater fish, can tolerate brackish waters and demonstrate physiological acclimation. However, their behavioural responses to brackish waters are unknown. The aim of the present study was therefore to investigate the activity and swimming behaviour of pikeperch obtained from freshwater canals in southern England. In the laboratory, fish were exposed to a 12-h simulated tidal cycle and a 12-day stepped salinity challenge where salinity was increased by 4 every 2 days, up to a salinity of 20. In both regimes, fish showed increased swimming activity in response to increasing salinity, which may represent an avoidance response. The most dramatic changes, including vertical movements, occurred at salinities above ~16. At these higher salinities, head shaking and coughing behaviours were also observed, suggesting significant stress and respiratory impairment. However, during the simulated tidal cycle, normal behaviour was rapidly restored once salinity was reduced. The results of this study may have implications in understanding the dispersal of non-native fish in the wild.
Use of an annular chamber for testing thermal preference of westslope cutthroat trout and rainbow trout.
Remaining populations of westslope cutthroat trout (Oncorhynchus clarkii iewisi) in western North America are primarily confined to cold headwaters whereas nonnative rainbow trout (Oncorhynchus mykiss) predominate in warmer, lower elevation stream sections historically occupied by westslope cutthroat trout. We tested whether differing thermal preferences could account for the spatial segregation observed in the field. Thermal preferences of age-1 westslope cutthroat trout and rainbow trout (125 to 150 mm total length) were assessed in the laboratory using a modified annular preference chamber at acclimation temperatures of 10, 12, 14, and 16°C. Final preferred temperature of westslope cutthroat trout (14.9°C) was similar to that of rainbow trout (143°C) when tested in a thermal gradient of 11–17°C. The high degree of overlap in thermal preference indicates the two species have similar thermal niches and a high potential for competition. We suggest several modifications to the annular preference chamber to improve performance in future studies.
The responses of Atlantic cod (Gadus morhua L.) to ultrasound-emitting predators: stress, behavioural changes or debilitation?.
A previous study has reported that Atlantic cod can be conditioned to detect ultrasonic sound pulses of high intensity. This capability has been proposed as a mean for detection and avoidance of echolocating toothed whales that emit intense ultrasonic clicks. In this study, we use acoustic playbacks to test the hypotheses that unconditioned cod can detect and respond to intense ultrasound from toothed whales and from echosounders. Intense ultrasound exposure of 210 dB re. 1μPa (pp) did not cause a short-term stress response in the form of bradycardia in unconditioned cod. Free-swimming cod exposed to ultrasonic clicks and echosounder pulses with received levels of more than 204 dB re. 1 μPa (pp) did not elicit flight responses as seen in ultrasound detecting Alosinae. Furthermore, we tested the debilitating effects of high intensity ultrasound on swimming cod with no detected changes in swimming ability when exposed to more than 213 dB re. 1 μPa (pp). It is concluded that intense ultrasound exposure induces neither an antipredator nor a stress response in Atlantic cod, and that echosounder pulses and biosonar clicks therefore most probably play no ecophysiological role in wild cod populations.
Dietary carotenoid availability influences a male's ability to provide parental care.
Despite convincing evidence that carotenoid availability can have positive physiological effects, we still lack information on the functional consequences of carotenoid limitation at the behavioral level. Given the role carotenoids play in mitigating oxidative stress produced during physical activity and as immunostimulants, one behavioral function on which they may have a significant impact is an individual's capacity to provide parental care. We tested this hypothesis using three-spined sticklebacks ( Gasterosteus aculeatus ), a species in which males provide obligate and intensive paternal care. Males were fed either high or low (but biologically realistic) levels of carotenoids and monitored throughout incubation, during which we quantified 2 key aspects of parental care: their ability to fan their eggs under normoxic and hypoxic conditions (when both the costs and requirements of fanning increase) and their ability to defend their nest against a simulated conspecific male. High-carotenoid diet males fanned their eggs at a significantly higher rate during hypoxic (but not normoxic) conditions and had higher clutch hatching success than males fed the low-carotenoid diet. There was no evidence that they defended their nest more aggressively. Furthermore, low-carotenoid diet males also appeared to engage in cannibalization of their clutch. These results demonstrate that dietary carotenoid availability can affect a male's ability to provide parental care, and we discuss the potential mechanisms and implications of this finding.
The relationship between caudal differential pressure and activity of Atlantic cod: a potential method to predict oxygen consumption of free-swimming fish.
This study reports the first results on telemetry of caudal differential pressure during spontaneous swimming activity in cod Gadus morhua and demonstrates that tail‐beat pressure may be used as a predictor of activity and swimming costs of free‐swimming cod. Tail‐beat pressure was monitored using a differential pressure sensor on the caudal peduncle of cod and spontaneous swimming activity was quantified using a customized video‐computer tracking programme. Tail‐beat pressure was found to correlate with (1) swimming speed ( U ) and oxygen consumption during forced swimming and (2) mean U during spontaneous activity. Based on the relationship between and the integrated pressure performed by the tail during forced swimming, it should be possible to predict during spontaneous activity. To gain precise measures of activity and thus predictions of for free‐swimming fish, however, individual calibrations are necessary.
Influence of Swimming Speed on Metabolic Rates of Juvenile Pacific Bluefin Tuna and Yellowfin Tuna.
Bluefin tuna are endothermic and have higher temperatures, heart rates, and cardiac outputs than tropical tuna. We hypothesized that the increased cardiovascular capacity to deliver oxygen in bluefin may be associated with the evolution of higher metabolic rates. This study measured the oxygen consumption of juvenile Pacific bluefin Thunnus orientalis and yellowfin tuna Thunnus albacares swimming in a swim-tunnel respirometer at 20°C. Oxygen consumption ( Mo2) of bluefin (7.1–9.4 kg) ranged from 235 ± 38 mg kg-1 h-1 at 0.85 body length (BL) s-1 to 498 ± 55 mg kg-1 h-1 at 1.80 BL s-1. Minimal metabolic rates of swimming bluefin were 222 ± 24 mg O2 kg-1 h-1 at speeds of 0.75 to 1.0 BL s-1. Mo2 of T. albacares (3.7–7.4 kg) ranged from 164 ± 18 mg kg-1 at 0.65 BL s-1 to 405 ± 105 mg kg-1 h-1 at 1.8 BL s-1. Bluefin tuna had higher metabolic rates than yellowfin tuna at all swimming speeds tested. At a given speed, bluefin had higher metabolic rates and swam with higher tailbeat frequencies and shorter stride lengths than yellowfin. The higher Mo2 recorded in Pacific bluefin tuna is consistent with the elevated cardiac performance and enhanced capacity for excitation-contraction coupling in cardiac myocytes of these fish. These physiological traits may underlie thermal-niche expansion of bluefin tuna relative to tropical tuna species.
Swimming Performance of Sacramento Splittail Injected with Subcutaneous Marking Agents.
Mark–recapture studies are often used at fish-screening facilities near water diversions, such as those in the Sacramento–San Joaquin Delta, to quantify fish salvage efficiency. The accuracy of these salvage estimates and subsequent facility operational criteria are highly dependent on unbiased mark–recapture estimates. Marking techniques and agents that produce reduced swimming performance in marked fish could result in inaccurate estimates of fish salvage and facility efficiency. Two of the most commonly used marking agents and techniques for experimental purposes at these screening facilities are the subcutaneous injection of visual implant elastomers using a hypodermic needle and the subcutaneous injection of fluorescent latex microsphere solutions using a CO2-powered pneumatic marking gun. We tested the effects of these marking agents and techniques on the critical swimming velocity (Ucrit) of age-1 Sacramento splittail Pogonichthys macrolepidotus (mean ± SE total length = 9.9 ± 0.6 cm, wet weight = 9.1 ± 1.8 g), which were marked in the caudal peduncle or caudal fin. Absolute Ucrit (64.8 ± 5.2 cm/s) and relative Ucrit (7.0 ± 1.1 body lengths/s) were unaffected by marking technique or marking agent (2-way ANOVA). Our results suggest that the tested marking agents and techniques are suitable for use in mark–recapture studies because they are unlikely to affect the capture probability of fish through reductions in swimming performance.
Mechanical and energetic factors underlying gait transitions in Bluegill Sunfish (Lepomis macrochirus).
As their swimming speed increased, bluegill sunfish (Lepomis macrochirus) switched from pectoral-fin-powered labriform swimming to undulations of the body axis. This gait transition occurred at a mean swimming speed of 0.24±0.01 m s–1 and a pectoral fin beat frequency of 2.79±0.11 Hz (mean ± s.e.m., N=6). The power output available from the main upstroke (adductor profundus) and downstroke (abductor superficialis) muscles, measured using the work-loop technique was maximal at the gait transition point. The cost of transport,measured by respirometry, increased as the fish switched from labriform to undulatory swimming. Our data show that bluegill changed gait as swimming speed increased to recruit additional muscle mass, rather than to maximize economy, as is the case for many terrestrial animals.
Efficiency of labriform swimming in the Bluegill Sunfish (Lepomis macrochirus).
Bluegill sunfish (Lepomis macrochirus) swim in the labriform mode at low speeds, generating lift and thrust by beating their pectoral fins. The maximal power output available from the two largest pectoral fin adductor and abductor muscles, constituting half of the total pectoral girdle muscle mass,was measured in vitro and used to estimate the muscle mechanical power output during maximal labriform swimming (Pmech;0.15–0.21 W kg–1 body mass). Respirometry was used to estimate the total metabolic power input (Ptotal; 0.95 W kg–1 body mass) and the metabolic power available to the active muscle mass (Pmuscle; Ptotalminus standard metabolic rate, 0.57 W kg–1 body mass) at this swimming speed. Drag measurements made on towed, dead fish were used to estimate the mechanical power required to overcome body drag(Pdrag; 0.028 W kg–1 body mass). Efficiency estimates based on these data fell into the following ranges:overall swimming efficiency(ηgross=Pmech/Ptotal),0.16–0.22; muscle efficiency(ηmuscle=Pmech/Pmuscle),0.26–0.37; and propeller efficiency(ηprop=Pdrag/Pmech),0.15–0.20. Comparison with other studies suggests that labriform swimming may be more efficient than swimming powered by undulations of the body axis.
Effects of temperature, swimming speed and body mass on standard and active metabolic rate in vendace (Coregonus albula).
This study gives an integrated analysis of the effects of temperature, swimming speed and body mass on standard metabolism and aerobic swimming performance in vendace (Coregonus albula (L.)). The metabolic rate was investigated at 4, 8 and 15°C using one flow-through respirometer and two intermittent-flow swim tunnels. We found that the standard metabolic rate (SMR), which increased significantly with temperature, accounted for up to 2/3 of the total swimming costs at optimum speed (U opt), although mean U opt was high, ranging from 2.0 to 2.8 body lengths per second. Net swimming costs increased with swimming speed, but showed no clear trend with temperature. The influence of body mass on the metabolic rate varied with temperature and activity level resulting in scaling exponents (b) of 0.71–0.94. A multivariate regression analysis was performed to integrate the effects of temperature, speed and mass (AMR = 0.82M 0.93 exp(0.07T) + 0.43M 0.93 U 2.03). The regression analysis showed that temperature affects standard but not net active metabolic costs in this species. Further, we conclude that a low speed exponent, high optimum speeds and high ratios of standard to activity costs suggest a remarkably efficient swimming performance in vendace.
The interactive effect of exercise and feeding on oxygen uptake, activity levels, and gastric processing in the graceful crab Cancer magister.
Exercise and digestive processes are known to elevate the metabolic rate of organisms independently. In this study, the effects of simultaneous exercise and digestion were examined in the graceful crab Cancer gracilis. This species exhibited resting oxygen uptake levels between 29 and 42 mg O(2) kg(-1) h(-1). In postprandial crabs, oxygen uptake was approximately double that of unfed crabs. During exercise, oxygen uptake increased three- to fourfold, reaching maximal levels of more than 130 mg O(2) kg(-1 ) h(-1). However, there was no difference in oxygen uptake during activity between unfed and postprandial animals. There was also no difference in exercise endurance levels between unfed and postprandial animals; both sets of animals were unable to right themselves after being turned on their backs, reaching exhaustion after 13-15 attempts. To determine whether increased activity affected gastric processes, the passage of a meal through the digestive system was followed using a fluoroscope. Passage of digesta through the gut system was slower in active animals than in resting crabs. Resting crabs cleared the foregut after approximately 18 h, which was significantly faster than the 34.5 h for constantly active animals. Likewise, the midgut region of resting animals was cleared at a faster rate than that of active animals. Because of residual amounts of digesta remaining in the hindgut, no difference in clearance rates of this section of the gut was evident. The slower clearance times of the foregut were due to a significantly slower rate of mastication of food, as evidenced by a lower cardiac stomach contraction rate. Contraction of the pyloric region of the foregut functions to move the digesta along the midgut, and there was a direct correlation between slower contraction rates of this region and the increased time of passage for digesta through the midgut of active animals. Because increased activity levels affected gastric processing, the crabs exhibited a behavioral response. During a 24-h period after feeding, there was a significant reduction in locomotor activity. The findings of this study suggest a prioritization of metabolic responses toward activity at the expense of digestion. This is discussed in relation to the ability of the crabs to balance the demands of competing physiological systems.
Effect of ration size and hypoxia on the specific dynamic action in the cod.
We present the first data on the effect of hypoxia on the specific dynamic action (SDA) in a teleost fish. Juvenile cod (Gadus morhua) were fed meals of 2.5% and 5% of their wet body mass (BM) in normoxia (19.8 kPa Po(2)) and 5% BM in hypoxia (6.3 kPa Po(2)). Reduced O(2) availability depressed the postprandial peaks of oxygen consumption, and to compensate for this, the total SDA duration lasted 212.0+/-20 h in hypoxia, compared with 95.1+/-25 h in normoxia. The percentage of energy associated with the meal digestion and assimilation (SDA coefficient) was equivalent between the different feeding rations but higher for fish exposed to hypoxia. Comparing peak oxygen consumption during the SDA course with maximum metabolic rates showed that food rations of 2.5% and 5% BM reduced the scope for activity by 40% and 55%, while ingestion of 5% BM in hypoxia occupied 69% of the aerobic scope, leaving little energy for other activities.
The autonomic control and functional significance of the changes in heart rate associated with air breathing in the jeju, Hoplerythrinus unitaeniatus.
The jeju is a teleost fish with bimodal respiration that utilizes a modified swim bladder as an air-breathing organ (ABO). Like all air-breathing fish studied to date, jeju exhibit pronounced changes in heart rate(fH) during air-breathing events, and it is believed that these may facilitate oxygen uptake (MO2) from the ABO. The current study employed power spectral analysis (PSA) of fH patterns, coupled with instantaneous respirometry, to investigate the autonomic control of these phenomena and their functional significance for the efficacy of air breathing. The jeju obtained less than 5%of total MO2(MtO2) from air breathing in normoxia at 26°C, and PSA of beat-to-beat variability in fHrevealed a pattern similar to that of unimodal water-breathing fish. In deep aquatic hypoxia (water PO2=1 kPa) the jeju increased the frequency of air breathing (fAB) tenfold and maintained MtO2 unchanged from normoxia. This was associated with a significant increase in heart rate variability (HRV),each air breath (AB) being preceded by a brief bradycardia and then followed by a brief tachycardia. These fH changes are qualitatively similar to those associated with breathing in unimodal air-breathing vertebrates. Within 20 heartbeats after the AB, however, a beat-to-beat variability in fH typical of water-breathing fish was re-established. Pharmacological blockade revealed that both adrenergic and cholinergic tone increased simultaneously prior to each AB, and then decreased after it. However, modulation of inhibitory cholinergic tone was responsible for the major proportion of HRV, including the precise beat-to-beat modulation of fH around each AB. Pharmacological blockade of all variations in fH associated with air breathing in deep hypoxia did not, however, have a significant effect upon fAB or the regulation of MtO2. Thus, the functional significance of the profound HRV during air breathing remains a mystery.
The effect of hypoxia on behavioral and physiological aspects of lesser sandell, Ammodytes tobianus.
Lesser sandeel (Ammodytes tobianus) is abundant in near-shore areas where it is a key prey. It exhibits the behaviour of alternating between swimming in schools and lying buried in the sediment. We first determined the species’ standard metabolic rate (SMR), critical partial pressure of oxygen $$(P_{{\rm O}_{2{\rm crit}}})$$ and maximal oxygen uptake $$(M_{{\rm O}_{2{\rm max}}}).$$ The sandeel were then exposed to an acute stepwise decline in water oxygen pressure (18.4, 13.8, 9.8, 7.5, 5.8, 4.0, and 3.1 kPa $$P_{{\rm O}_{2}}$$ ). Swimming speed and routine- and post-experimental blood lactate levels were measured, in addition to levels associated with strenuous exercise. The SMR was 69.0 ± 8.4 mg O2 kg−1 h−1 and the $$M_{{\rm O}_{2{\rm max}}}$$ about seven times as high. The $$P_{{\rm O}_{2{\rm crit}}}$$ was found to be 4.1 kPa. A rapid decrease (within 1 h) in $$P_{{\rm O}_{2}}$$ from 18.4 to 3.1 kPa had no significant effect on routine swimming speed (0.9 ± 0.06 bl s−1), but steady levels at the lowest $$P_{{\rm O}_{2}}$$ (3.1 kPa) gradually reduced the swimming speed by 95% after 40 min. The routine blood lactate levels were 2.2 ± 0.6 mmol l−1, while the levels in the strenuously exercised groups were significantly higher with 5.4 ± 1.6 and 5.8 ± 1.3 mmol l−1. The highest levels were observed in post-experimental fish with 7.5 ± 2.7 mmol l−1. We argue that, as sandeel showed no decrease in swimming speed (to offset stress) nor an increased speed to escape the hypoxia, the fish either rely on a low SMR and being a reasonable strong oxygen regulator $$(\hbox{low}\;P_{{\rm O}_{2{\rm crit}}})$$ as a mean to cope when exposed to acute hypoxia, or that the hypoxia simply developed too fast for the fish to decide on an appropriate strategy. Not showing a behavioural response may in the present case be maladaptive, as the consequence was major physiological stress which the fish however appears tolerant towards. The high routine blood lactate levels suggest that anaerobic metabolism is associated with swimming in sandeel, which may be related to the specific lifestyle of the fish where they regularly bury in the sediment.
Can sunbleak Leucaspius delineatus or topmouth gudgeon Pseudorasbora parva disperse through saline waters?
In order to determine the potential for the invasive fishes sunbleak Leucaspius delineatus and topmouth gudgeon Pseudorasbora parva to disperse through saline waters their behaviour and physiology were investigated during exposure to salinities of 10·0 and 12·5. Increased salinity caused an increase in whole body cortisol in both species, but sunbleak and topmouth gudgeon showed very different metabolic and behavioural responses to the salinity stress. Sunbleak displayed increased swimming activity in brackish water, which may be important for dispersal through saline waters in the wild, although there were increased metabolic costs associated with this behaviour. Conversely, topmouth gudgeon showed a reduction in both swimming activity and metabolic rate in brackish waters. A pronounced depression in food intake (70–80%) was shown by both species during the salinity exposures. Both sunbleak and topmouth gudgeon, however, showed a full recovery of food intake within 24 h following return to fresh water. Despite the fact that exposure to saline waters is stressful, and affects both physiology and behaviour, rapid recovery of appetite after return to fresh water suggests that short‐term use of brackish waters is a feasible dispersal route for sunbleak and topmouth gudgeon in the wild.
Effect of turbidity on habitat preference of juvenile Atlantic cod, Gadus morhua.
We examined the effects of turbidity on habitat preference of juvenile Atlantic cod in the laboratory, using a shuttle box where fish could select between two different habitats. In the first experiment, we compared three turbidity levels of kaolin (3, 8 and 21 beam attenuation m−1). In the second experiment, we looked at the effect of turbidity media (kaolin versus algae), after controlling for spectral differences between turbidity media. Although cod preferred an intermediate turbidity of kaolin over low turbidity water, comparisons between low and high turbidity, and intermediate and high turbidity did not significantly influence habitat preference. Algae did not influence habitat preference by cod. Although other studies have found that turbidity affects both foraging and antipredator behaviour of juvenile cod, this study has shown that gradients in turbidity per se do not have a strong effect on their habitat preference.
Cyclic feeding and subsequent compensatory growth do not significantly impact standard metabolic rate or critical swimming speed in rainbow trout.
Standard metabolic rate ( R s ) and critical swimming speed ( U crit ) were used to assess the aspects of physiological status (stamina) of rainbow trout Oncorhynchus mykiss. Fish were fed either 1·5% body mass daily, 1·5% body mass cyclically (3 weeks of food deprivation followed by 3 weeks of refeeding), a ration based on Stauffer’s formula (a maximum temperature‐specific ration level) daily or on Stauffer’s ration cyclically for 18 weeks. It was hypothesized that if cyclic feeding had no impact on the status of the fish, R s and U crit would not cycle with the feeding regime. This hypothesis was supported. No significant difference was found between the mean mass and the fork length of the four groups at the end of the experiment ( P > 0·05). Feeding had no effect on changes in R s among the four groups, which were significantly different throughout the experiment ( P ≤ 0·05). No significant difference in U crit was found ( P > 0·05) until at week 12 between groups fed 1·5% body mass ration cyclically and Stauffer’s ration daily ( P ≤ 0·05). For groups fed a 1·5% body mass ration cyclically and daily, significant differences occurred at week 15 ( P ≤ 0·05) but no significant difference was found by week 18 ( P > 0·05), suggesting that cyclic feeding does not affect the aspects of physiological status (stamina) of the fish.
The effect of external dummy transmitters on oxygen consumption and performance of swimming Atlantic cod
Decreased critical swimming speed and increased oxygen consumption ( ) was found for externally tagged Atlantic cod Gadus morhua swimming at a high speed of 0·9 body length (total length, L T ) s −1. No difference was found in the standard metabolic rate, indicating that the higher for tagged cod was due to drag force rather than increased costs to keep buoyancy.
Use of a Novel Acoustic Dissolved Oxygen Transmitter for Fish Telemetry.
The multiple responses of fishes to changes in dissolved oxygen saturations have been studied widely in the laboratory. In contrast, only a few studies have included field observa- tions. The objective of the present study was to evaluate the performance of a novel acoustic dissolved oxygen transmitter for field biotelemetry. The results demonstrated that the output of the transmitter was unaffected by three different temperatures (10 to 30°C) and described the dissolved oxygen saturation with high accuracy (r 2 > 0.99) over the entire range of 0 to 191% saturation. The response time (≥ 90% of end value) of the transmitter was 12 s both in terms of decreasing (100 to 0%) and increasing (0 to 100%) oxygen saturations. When externally attached to fishes, the present findings support the use of the transmitter for reliable dissolved oxygen measurements on individuals living in environments that may change both temporally and spatially with regard to ambient temperature and dissolved oxygen saturation.
Effects of social environment and energy efficiency on preferred swim speed in a marine generalist fish, pile perch (Phanerodon vacca)
Energy efficiency is a key component of movement strategy for many species. In fish, optimal swimming speed (Uopt) is the speed at which the mass-specific energetic cost to move a given distance is minimised. However, additional factors may influence an individual's preferred swimming speed (Upref). Activities requiring consistent sensory inputs, such as food finding, may require slower swimming speeds than Uopt. Further, although the majority of fish display some form of social behaviour, the influence of social interactions on Upref remains unclear. It is unlikely that all fish within a group will have the same Upref, and fish may therefore compromise individual Upref to swim with a conspecific. This study measured the Uopt, Upref and Upref in the presence of a conspecific (Upair) of pile perch, Phanerodon vacca, a non-migratory coastal marine generalist. Uopt was significantly higher than, and was not correlated with, Upref. Fish therefore chose to swim at speeds below their energetic optimum, possibly because slower swimming allows for greater awareness of surroundings. Mean Upair was significantly lower than the Upref of the faster fish in each pair but did not differ significantly from the Upref of the slower fish. Therefore, faster fish appear to slow their speed to remain with a slower conspecific. Our study suggests that environmental factors, including social surroundings, may be more important than energetic efficiency for determining swim speed in P. vacca. Further studies of fish species from various habitats will be necessary to elucidate the environmental and energetic factors underpinning Upref.
Light pollution in the wild affects adult reef fish and has intergenerational and direct impacts on offspring
Artificial light at night (ALAN) is a pervasive anthropogenic pollutant, increasing in intensity and scope. While its impacts on biological and ecological processes are well documented among terrestrial taxa, marine organisms have received less attention, though a quarter of the world’s coastlines are affected by artificial light at night. Furthermore, the intergenerational effects of artificial light at night have never been documented in the wild. We conducted a field manipulation experiment in the lagoon of Mo’orea, French Polynesia, using LED (Light-Emitting Diode) lights to test artificial light at night’s effects on adult life-history and offspring fitness of the coral reef anemonefish Amphiprion chrysopterus. Exposing adults and embryos to LEDs, we found artificial light at night enhanced adult growth but did not alter measured reproductive traits, including fecundity. We observed reduced parental reproductive hormone levels with downstream consequences for offspring. Hatching success was unchanged, but offspring showed reduced embryonic heart rate and yolk sac size, and drastically diminished larval escape responses and swimming performance. This comprehensive study is the first in a wild organism to demonstrate combined intergenerational and direct negative effects of artificial light at night, highlighting limited compensatory capacity. These impacts could impair larval recruitment and hinder population replenishment in reef fish. This research underscores urgent need for conservation and management to address artificial lighting impacts.
Cryopreservation and revival of Hawaiian stony corals using isochoric vitrification
Corals are under siege by both local and global threats, creating a worldwide reef crisis. Cryopreservation is an important intervention measure and a vital component of the modern coral conservation toolkit, but preservation techniques are currently limited to sensitive reproductive materials that can only be obtained a few nights per year during spawning. Here, we report the successful cryopreservation and revival of cm-scale coral fragments via mL-scale isochoric vitrification. We demonstrate coral viability at 24 h post-thaw using a calibrated oxygen-uptake respirometry technique, and further show that the method can be applied in a passive, electronics-free configuration. Finally, we detail a complete prototype coral cryopreservation pipeline, which provides a platform for essential next steps in modulating post-thaw stress and initiating long-term growth. These findings pave the way towards an approach that can be rapidly deployed around the world to secure the biological genetic diversity of our vanishing coral reefs.
Functional trajectories during innate spinal cord repair
Adult zebrafish are capable of anatomical and functional recovery following severe spinal cord injury. Axon growth, glial bridging and adult neurogenesis are hallmarks of cellular regeneration during spinal cord repair. However, the correlation between these cellular regenerative processes and functional recovery remains to be elucidated. Whereas the majority of established functional regeneration metrics measure swim capacity, we hypothesize that gait quality is more directly related to neurological health. Here, we performed a longitudinal swim tracking study for 60 individual zebrafish spanning 8 weeks of spinal cord regeneration. Multiple swim parameters as well as axonal and glial bridging were integrated. We established rostral compensation as a new gait quality metric that highly correlates with functional recovery. Tensor component analysis of longitudinal data supports a correspondence between functional recovery trajectories and neurological outcomes. Moreover, our studies predicted and validated that a subset of functional regeneration parameters measured 1 to 2 weeks post-injury is sufficient to predict the regenerative outcomes of individual animals at 8 weeks post-injury. Our findings established new functional regeneration parameters and generated a comprehensive correlative database between various functional and cellular regeneration outputs.
Swimming Behavioural Responses and Impingement Risks of Larval Golden Perch to Fish Protection Screen Approach Velocities
Fish protection screens are increasingly being considered as management tools to prevent significant numbers of fish being extracted from Australian rivers at water diversions. Australian design standards specify an approach velocity (the perpendicular flow 8cm in front of the screen) of 0.1 m.s−1. This value was based on studies on juvenile fish, but the extent that it protects larval fish is understudied. The swimming of three ontogenetic stages of Golden perch larvae (protolarvae, postflexion and metalarvae) was observed in front of a screen in a variable speed swimming flume. Approach velocity and water temperature were varied, and the likelihood of impingement and the time for impingement to occur was measured. Swimming behaviours employed by fish to avoid impingement were also quantified. Protolarvae were the most susceptible, with almost 100% impingement at all tested velocities. Impingement became less likely as larvae increased in age. However, at velocities above 0.10 m.s−1 impingement likelihood increased for all stages. The results indicate that if an approach velocity of 0.10 m.s−1 is adhered to, that a critical time of 10 s is available in which larvae may be protected. Larvae implemented key behaviours to avoid impingement, which changed as they developed morphologically. Protolarvae displayed use of hydraulic refuging behaviours, whilst postflexion and metalarvae used a burst and coast strategy. Those that did not implement these behaviours became impinged. Current Australian specifications for fish protection screen design can therefore facilitate the protection of larval Golden perch. Protection improves significantly as larvae develop beyond the protolarval stage.
A burning issue: The effect of organic ultraviolet filter exposure on the behaviour and physiology of Daphnia magna
Ultraviolet (UV) filters are compounds utilized in many manufacturing processes and personal care products such as sunscreen to protect against UV-radiation. These highly lipophilic compounds are emerging contaminants of concern in aquatic environments due to their previously observed potential to bioaccumulate and exert toxic effects in marine ecosystems. Currently, research into the toxic effects of UV filter contamination of freshwater ecosystems is lacking, thus the present study sought to model the effects of acute and chronic developmental exposures to UV filters avobenzone, oxybenzone and octocrylene as well as a mixture of these substances in the freshwater invertebrate, Daphnia magna, at environmentally realistic concentrations. Median 48-hour effect and lethal concentrations were determined to be in the low mg/L range, with the exception of octocrylene causing 50% immobilization near environmental concentrations. 48-hour acute developmental exposures proved to behaviourally impair daphnid phototactic response; however, recovery was observed following a 19-day post-exposure period. Although no physiological disruptions were detected in acutely exposed daphnids, delayed mortality was observed up to seven days post-exposure at 200 μg/L of avobenzone and octocrylene. 21-day chronic exposure to 7.5 μg/L octocrylene yielded complete mortality within 7 days, while sublethal chronic exposure to avobenzone increased Daphnia reproductive output and decreased metabolic rate. 2 μg/L oxybenzone induced a 25% increase in metabolic rate of adult daphnids, and otherwise caused no toxic effects at this dose. These data indicate that UV filters can exert toxic effects in freshwater invertebrates, therefore further study is required. It is clear that the most well-studied UV filter, oxybenzone, may not be the most toxic to Daphnia, as both avobenzone and octocrylene induced behavioural and physiological disruption at environmentally realistic concentrations.
Acute cardiorespiratory effects of 6PPD-quinone on juvenile rainbow trout (Oncorhynchus mykiss) and arctic char (Salvelinus alpinus)
N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone (6PPD-quinone) is an environmental transformation product of the widely used rubber tire antioxidant, 6PPD. Found in stormwater runoff, 6PPD-quinone has been reported to cause acute lethality at ≤1 μg/L in salmonids like coho salmon, rainbow trout, and brook trout. Conversely, other species such as Arctic char and brown trout are insensitive, even when exposed to significantly greater concentrations (3.8–50 μg/L). Sensitive species exhibit symptoms such as gasping, spiraling, increased ventilation, and loss of equilibrium, suggesting a possible impact on cardiorespiratory physiology. This study investigated sublethal 6PPD-quinone toxicities, focusing on cardiovascular and metabolic effects in two salmonids of varying sensitivity: a sensitive species, rainbow trout (Oncorhynchus mykiss) and a tolerant species, Arctic char (Salvelinus alpinus). Fish were exposed to measured concentrations of 0.59 or 7.15 μg/L 6PPD-quinone, respectively, in respirometry chambers for 48 h to assess temporal changes in resting oxygen consumption compared to unexposed controls. Following exposure, cardiac ultrasound and electrocardiography characterized cardiac function in vivo, while blood gas analysis examined blood composition changes. In both species, changes in resting oxygen consumption were observed. In rainbow trout only, a decrease in end systolic volume and an increase in passive ventricular filling, cardiac output, and PR interval length were observed, indicating cardiac stimulation. Cardiorespiratory symptoms observed following rainbow trout exposure might partly be driven by a significant increase in methemoglobin, resulting in an impaired ability to oxygenate tissues. This study is the first to examine the effects of 6PPD-quinone exposure on the cardiorespiratory system of salmonid fishes and provides information invaluable to a better understanding of the mechanism of 6PPD-quinone toxicity.
Selection for Postponed Senescence in Drosophila melanogaster Reveals Distinct Metabolic Aging Trajectories Modifiable by the Angiotensin‐Converting Enzyme Inhibitor Lisinopril
Aging is accompanied by profound changes in energy metabolism, yet the underlying drivers and modulators of these shifts remain incompletely understood. Here, we investigated how life‐history evolution shapes metabolic aging and pharmacological responsiveness by leveraging Drosophila melanogaster lines divergently selected for reproductive timing. We measured organismal oxygen consumption rate and performed untargeted metabolomics in young and old flies of both sexes from long‐lived “O” lines (selected for female late‐life reproduction) and unselected “B” control lines. Males and females from the O lines maintained stable metabolic rates and largely preserved metabolite profiles with age, whereas B line flies showed age‐related increases in oxygen consumption, citrate accumulation, and elevated levels of medium‐ and long‐chain fatty acids, hallmarks of mitochondrial inefficiency and impaired lipid oxidation. Aged B flies also displayed elevated S‐adenosylmethionine, reduced sarcosine, and diminished heme levels, indicating dysregulation of one‐carbon metabolism and impaired heme biosynthesis. Furthermore, Vitamin B6 metabolites, pyridoxamine, pyridoxal, and 4‐pyridoxate, increased with aging only in B line females. Motivated by evidence implicating the renin‐angiotensin system in metabolic aging, we treated flies with the angiotensin‐converting enzyme (ACE) inhibitor lisinopril. Lisinopril prevented the age‐related rise in metabolic rate in B line females, aligning their metabolic phenotype with that of O line flies. This suggests that ACE inhibition may buffer against age‐associated increases in metabolic rate and contribute to enhanced metabolic stability. Our results show that selection for delayed reproduction and increased lifespan modifies age‐related metabolic trajectories and modulates physiological responses to pharmacological intervention.
The Impact of the Angiotensin-Converting Enzyme Inhibitor Lisinopril on Metabolic Rate in Drosophila melanogaster
Evidence suggests that angiotensin-converting enzyme inhibitors (ACEIs) may increase metabolic rate by promoting thermogenesis, potentially through enhanced fat oxidation and improved insulin. More research is, however, needed to understand this intricate process. In this study, we used 22 lines from the Drosophila Genetic Reference Panel to assess the metabolic rate of virgin female and male flies that were either fed a standard medium or received lisinopril for one week or five weeks. We demonstrated that lisinopril affects the whole-body metabolic rate in Drosophila melanogaster in a genotype-dependent manner. However, the effects of genotypes are highly context-dependent, being influenced by sex and age. Our findings also suggest that lisinopril may increase the Drosophila metabolic rate via the accumulation of a bradykinin-like peptide, which, in turn, enhances cold tolerance by upregulating Ucp4b and Ucp4c genes. Finally, we showed that knocking down Ance, the ortholog of mammalian ACE in Malpighian/renal tubules and the nervous system, leads to opposite changes in metabolic rate, and that the effect of lisinopril depends on Ance in these systems, but in a sex- and age-specific manner. In conclusion, our results regarding D. melanogaster support existing evidence of a connection between ACEI drugs and metabolic rate while offering new insights into this relationship.
Developmental defects in cognition, metabolic and cardiac function following maternal exposures to low environmental levels of selective serotonin re-uptake inhibitors and tributyltin in Daphnia magna
Aquatic organisms are exposed to low concentrations of neuro-active chemicals, many of them acting also as neuroendocrine disruptors that can be hazardous during earlier embryonic stages. The present study aims to assess how exposure early in live to environmental low concentrations of two selective serotonin reuptake inhibitors (SSRIs), fluoxetine and sertraline, and tributyltin (TBT) affected cognitive, metabolic and cardiac responses in the model aquatic crustacean Daphnia magna. To that end, newly brooded females were exposed for an entire reproductive cycle (3-4 days) and the response of collected juveniles in the first, second and third consecutive broods, which were exposed, respectively, as embryos, provisioned and un-provisioned egg stages, was monitored. Pre-exposure to the selected SSRIs during embryonic and egg developmental stages altered the swimming behaviour of D. magna juveniles to light in a similar way reported elsewhere by serotonergic compounds while TBT altered cognition disrupting multiple neurological signalling routes. The studied compounds also altered body size, the amount of storage lipids in lipid droplets, heart rate, oxygen consumption rates and the transcription of related serotonergic, dopaminergic and lipid metabolic genes in new-born individuals, mostly pre-exposed during their embryonic and provisioning egg stages. The obtained cognitive, cardiac and metabolic defects in juveniles developed from exposed sensitive pre-natal stages align with the "Developmental Origins of Health and Disease (DoHAD)" paradigm.
Tolerance of aquifer stoneflies to repeated hypoxia exposure and oxygen dynamics in an alluvial aquifer
Aquatic insects cope with hypoxia and anoxia using a variety of behavioral and physiological responses. Most stoneflies (Plecoptera) occur in highly oxygenated surface waters, but some species live underground in alluvial aquifers containing heterogeneous oxygen concentrations. Aquifer stoneflies appear to be supported by methane-derived food resources, which they may exploit using anoxia-resistant behaviors. We documented dissolved oxygen dynamics and collected stoneflies over five years in floodplain wells of the Flathead River, Montana. Hypoxia regularly occurred in two wells, and nymphs of Paraperla frontalis were collected during hypoxic periods. We measured mass-specific metabolic rates (MSMR) at different oxygen concentrations (12, 8, 6, 4, 2, 0.5 mg/L, and during recovery) for 111 stonefly nymphs to determine whether aquifer and benthic taxa differed in hypoxia tolerance. Metabolic rates of aquifer taxa were similar across oxygen concentrations spanning 12 to 2 mg/L (P>0.437), but rates of benthic taxa dropped significantly with declining oxygen (P<0.0001; 2.9× lower at 2 vs. 12 mg/L). Aquifer taxa tolerated short-term repeated exposure to extreme hypoxia surprisingly well (100% survival), but repeated longer-term (> 12 hours) exposures resulted in lower survival (38-91%) and lower metabolic rates during recovery. Our work suggests that aquifer stoneflies have evolved a remarkable set of behavioral and physiological adaptations that allow them to exploit the unique food resources available in hypoxic zones. These adaptations help explain how large-bodied consumers might thrive in the underground aquifers of diverse and productive river floodplains.
Are acute and acclimated thermal effects on metabolic rate modulated by cell size? A comparison between diploid and triploid zebrafish larvae
Being composed of small cells may carry energetic costs related to maintaining ionic gradients across cell membranes as well as benefits related to diffusive oxygen uptake. Here, we test the hypothesis that these costs and benefits of cell size in ectotherms are temperature dependent. To study the consequences of cell size for whole-organism metabolic rate, we compared diploid and triploid zebrafish larvae differing in cell size. A fully factorial design was applied combining three different rearing and test temperatures that allowed us to distinguish acute from acclimated thermal effects. Individual oxygen consumption rates of diploid and triploid larvae across declining levels of oxygen availability were measured. We found that both acute and acclimated thermal effects affected the metabolic response. In comparison with triploids, diploids responded more strongly to acute temperatures, especially when reared at the highest temperature. These observations support the hypothesis that animals composed of smaller cells (i.e. diploids) are less vulnerable to oxygen limitation in warm aquatic habitats. Furthermore, we found slightly improved hypoxia tolerance in diploids. By contrast, warm-reared triploids had higher metabolic rates when they were tested at acute cold temperature, suggesting that being composed of larger cells may provide metabolic advantages in the cold. We offer two mechanisms as a potential explanation of this result, related to homeoviscous adaptation of membrane function and the mitigation of developmental noise. Our results suggest that being composed of larger cells provides metabolic advantages in cold water, while being composed of smaller cells provides metabolic advantages in warm water.
RNA virus-mediated changes in organismal oxygen consumption rate in young and old Drosophila melanogaster males
Aging is accompanied by increased susceptibility to infections including with viral pathogens resulting in higher morbidity and mortality among the elderly. Significant changes in host metabolism can take place following virus infection. Efficient immune responses are energetically costly, and viruses divert host molecular resources to promote their own replication. Virus-induced metabolic reprogramming could impact infection outcomes, however, how this is affected by aging and impacts organismal survival remains poorly understood. RNA virus infection of Drosophila melanogaster with Flock House virus (FHV) is an effective model to study antiviral responses with age, where older flies die faster than younger flies due to impaired disease tolerance. Using this aged host-virus model, we conducted longitudinal, single-fly respirometry studies to determine if metabolism impacts infection outcomes. Analysis using linear mixed models on Oxygen Consumption Rate (OCR) following the first 72-hours post-infection showed that FHV modulates respiration, but age has no significant effect on OCR. However, the longitudinal assessment revealed that OCR in young flies progressively and significantly decreases, while OCR in aged flies remains constant throughout the three days of the experiment. Furthermore, we found that the OCR signature at 24-hours varied in response to both experimental treatment and survival status. FHV-injected flies that died prior to 48- or 72-hours measurements had a lower OCR compared to survivors at 48-hours. Our findings suggest the hostâs metabolic profile could influence the outcome of viral infections.
Modulation of PFOA (perfluorooctanoic acid) uptake in Daphnia (Daphnia magna) by TiO2 nanoparticles
The hydrophobic surface of plastics adsorbs hydrophobic persistent organic pollutants (POP) such as Perfluorooctanoic acid (PFOA). The potential for hydrophobic nanoparticles such as titanium dioxide (TiO 2 ) to associate with PFOA and alter accumulation rates has not been investigated. Nanoparticles form ecocorona by adsorption of multiple constituents in water, but few studies have examined if this results in differences in the rate of PFOA accumulation in freshwater animals. We demonstrate the PFOA associates with the hydrophobic surfaces of nano-sized TiO 2 particles and this increases the rate of uptake of PFOA into Daphnia magna. Accumulation of PFOA in daphnia was measurement over multiple concentrations, flux times and particle sizes using a radiotracer-based method ( 14 C-labelled PFOA). Our results show that TiO 2 NPs have a high sorption capacity for PFOA and PFOA sorption decreased aggregation of TiO 2 as evidenced by a decrease in average hydrodynamic diameter, decreased zeta potential and increased polydispersity index. Uptake of PFOA at 10 μg/L was found to be 45 % higher in the presence of 500 μg/L of 5 nm TiO 2 compared to control PFOA alone uptake. Potentiation of PFOA uptake using 25 nm TiO 2 NPs was 25 % higher than control PFOA alone. PFOA alone (0.5 mg/L) reduced metabolic oxygen consumption (MO 2 ) in daphnia by 52 %, but exposure to (100 mg/L) 5 nm TiO 2 NPs sorbed with (0.5 mg/L) PFOA decreased metabolic oxygen consumption (MO 2 ) by ~88 %. These findings show that TiO 2 nanoparticles act as vectors for hydrophobic organic pollutant accumulation and significantly potentiate PFOA accumulation and toxicity in aquatic organisms.
Behavioural responses of juvenile Daphnia magna to two organophosphorus insecticides
In this study, the behaviour of Daphnia magna was studied under equipotent and sub-lethal concentrations of two pesticides congeners: chlorpyrifos (CPF; 5 ng L-1 to 50 ng L-1) and chlorpyrifos-methyl (CPF-m; 30 ng L-1 to 300 ng L-1) with aims to assess and compare the behavioural swimming responses (BSRs) of the cladocerans elicited by both compounds at different concentrations and exposure times. A video tracking analysis after 24 h and 48 h of exposure allowed us to evaluate different behavioural responses (distance moved, average velocity, active time, and average acceleration). The results indicate that BSRs are sensitive indicators of sub-lethal stress. Highly concentration- and time-response changes for both compounds were observed during the experiments. In particular, in the first 24 h of exposure, both compounds elicited a similar decreasing trend in swimming behaviour, in which CPF induced the highest decline. Further, hypoactivity was associated with the narcotic effects of both compounds. Conversely, after 48 h of exposure, we observed an increasing tendency in the swimming parameters, particularly at the highest tested concentrations. However, the compounds did not exhibit the same trend. Rather, CPF-m induced high variations from the control groups. This reversal trend could be due to the activation of compensatory mechanisms, such as feeding, searching, or avoidance behaviours. These results suggest that BSRs are measurable active responses of organisms, which are controlled by time.
The influence of the recording time in modelling the swimming behaviour of the freshwater inbenthic copepod Bryocamptus pygmaeus
Swimming Behavior of Percocypris pingi in the Wake of D-Shaped Obstacles: A Comparative Study of Single-and Dual-Fish Swimming in Complex Hydrodynamic Environments
Berry, Madeleine; Davidsen, Jan G; Nevoux, Marie; Aarestrup, Kim; Alexandre, Carlos M; Silva, Sara S; Thorén, Alexander; Engstöm, Anders; Ahvenainen, Matilda; Höjesjö, Johan (2025)
Interactive effects of hydrodynamics and microplastics on bioaccumulation, histopathological alterations, biomarker responses, and gene expression in grass carp brain
Identifying the optimal flow conditions of a fishway with two entrances for endemic fishes at a high-altitude hydropower station in the Tibetan Himalaya, China
Protective effects of Trifuhalol A, a Phlorotannin derived from edible Brown seaweed Agarum cribrosum, on dexamethasone-induced muscle atrophy in muscle cells and zebrafish models
Ocean acidification disrupts the energy balance and impairs the health of mussels (Mytilus coruscus) by weakening their trophic interactions with microalgae and intestinal microbiome
The contribution of tissue-specific mitochondrial respiration to individual variation in oxygen uptake during rest and exercise by the Gulf killifish, Fundulus grandis
Are standard test species still relevant? A comprehensive assessment of Daphnia pulex reared in laboratory and wild environments and their responses to organic ultraviolet filters
Temperature extremes and sex-related physiology, not environmental variability, are key in explaining thermal sensitivity of bimodal-breathing intertidal crabs
Anorexigenic and anxiogenic effects of the plasticiser DEHP (di-2-ethylhexyl phthalate) in goldfish: Involvement of PPAR signalling and feeding-related neuropeptides
Evaluation of methodology for measuring standard metabolic rates of crayfishes using the red swamp crayfish Procambarus clarkii (Girard, 1852)(Decapoda: Astacidea: Cambaridae)
Evaluating the metabolic response to temperature using otolith carbon isotopes as an intrinsic metabolic tracer in juvenile chum salmon Oncorhynchus keta
Taurine efflux counters the hydrodynamic impact of anaerobic metabolism to protect cardiorespiratory function under acute thermal stress in brook char (Salvelinus fontinalis)
When less is more for dietary Lactobacillus rhamnosus IMC 501: The complex role gut microbiota play in energy budgets and allostasis of early juvenile Mozambique Tilapia (Oreochromis mossambicus)
Multiple stressors affecting microbial decomposer and litter decomposition in restored urban streams: Assessing effects of salinization, increased temperature, and reduced flow velocity in a field mesocosm experiment
Corticotropin‐releasing hormone receptor 1 mediates the enhanced locomotor activity and metabolic demands to an acute thermal stress in adult zebrafish
Oxygen Consumption and Carbon Budget in Groundwater-Obligate and Surface-Dwelling Diacyclops Species (Crustacea Copepoda Cyclopoida) Under Temperature Variability
Swimming at Increasing Speeds in Steady and Unsteady Flows of Atlantic Salmon Salmo salar: Oxygen Consumption, Locomotory Behaviour and Overall Dynamic Body Acceleration
Gurr, Samuel J; McFarland, Katherine; Bernatchez, Genevieve; Dixon, Mark S; Guy, Lisa; Milke, Lisa M; Poach, Matthew E; Hart, Deborah; Plough, Louis V; Redman, Dylan H (2024)
Non-invasive determination of critical dissolved oxygen thresholds for stress physiology in fish using triple-oxygen stable isotopes and aquatic respirometry
Belding, Luke D; Thorstensen, Matt J; Quijada‐Rodriguez, Alex R; Bugg, William S; Yoon, Gwangseok R; Loeppky, Alison R; Allen, Garrett JP; Schoen, Alexandra N; Earhart, Madison L; Brandt, Catherine (2024)
Near maximally swimming schoolmaster snapper (Lutjanus apodus) have a greater metabolic capacity, and only a slightly lower thermal tolerance, than when tested at rest
Lonthair, Joshua K; Wegner, Nicholas C; Cheng, Brian S; Fangue, Nann A; O'Donnell, Matthew J; Regish, Amy M; Swenson, John D; Argueta, Estefany; McCormick, Stephen D; Letcher, Benjamin H (2024)
Exposure to alkaline water reduces thermal tolerance, but not thermal plasticity, in brook stickleback (Culaea inconstans) collected from an alkaline lake
Effects of exercise training on the external morphology, growth performance, swimming ability, body composition and metabolism of juvenile black seabream Acanthopagrus schlegelii
Metabolic scope and swimming performance of juvenile channel (Ictalurus punctatus), blue (I. furcatus), and hybrid (I. punctatus× I. furcatus) catfish at moderate and high temperatures
Oxygen consumption rate during recovery from loss of equilibrium induced by warming, hypoxia, or exhaustive exercise in rainbow darter (Etheostoma caeruleum)
Temperature and hypoxia trigger developmental phenotypic plasticity of cardiorespiratory physiology and growth in the parthenogenetic marbled crayfish, Procambarus virginalis Lyko, 2017
Improving the Aerobic Capacity in Fingerlings of European Sea Bass (Dicentrarchus labrax) through Moderate and Sustained Exercise: A Metabolic Approach
Microdosing ketamine in Drosophila does not block serotonin reuptake, but causes complex behavioral changes mediated by glutamate and serotonin receptors
A new mechanistic insight into the association between environmental perfluorooctane sulfonic acid (PFOS) exposure and attention deficit and hyperactivity disorder (ADHD)-like behavior
Lima, André RA; Booms, Emily M; Lopes, Ana Rita; Martins-Cardoso, Sara; Novais, Sara C; Lemos, Marco FL; Ribeiro, Laura; Castanho, Sara; Candeias-Mendes, Ana; Pousão-Ferreira, Pedro (2024)
Are bold-shy personalities of European perch (Perca fluviatilis) linked to stress tolerance and immunity? A scope of harnessing fish behavior in aquaculture
River zebrafish combine behavioral plasticity and generalized morphology with specialized sensory and metabolic physiology to survive in a challenging environment
The effect of chemical dispersion and temperature on the metabolic and cardiac responses to physically dispersed crude oil exposure in larval American lobster (Homarus americanus)
Integration of physiological and gene expression analyses to reveal biomarkers for protein dynamic mechanisms regulating higher growth and survival among larval oyster families (Crassostrea gigas)
Nutritional status affects Igf1 regulation of skeletal muscle myogenesis, myostatin, and myofibrillar protein degradation pathways in gopher rockfish (Sebastes carnatus)
Use of the shuttle box system to determine the effects of hypoxia and food deprivation on the behavioral responses of the rock crab Cancer irroratus Say, 1817 (Decapoda: Brachyura: Cancridae)
Laboratory‐based measures of temperature preference and metabolic thermal sensitivity provide insight into the habitat utilisation of juvenile California horn shark (Heterodontus francisci) and leopard shark (Triakis semifasciata)
The Unique Magnetic Signature of Sickle Red Blood Cells: A Comparison Between the Red Blood Cells of Transfused and Non-Transfused Sickle Cell Disease Patients and Healthy Donors
Influence of hypoxia on biochemical aspects and on expression of genes related to oxygen-homeostasis of the Amazonian cichlid Astronotus ocellatus (Agassiz, 1831)
Dixon, Toni-Anne M; Rhyno, Emma-Lee M; El, Nir; McGaw, Samuel P; Otley, Nathan A; Parker, Katya S; Buldo, Elena C; Pabody, Claire M; Savoie, Mireille; Cockshutt, Amanda (2023)
Reduced Hypoxia Tolerance and Altered Gill Morphology at Elevated Temperatures May Limit the Survival of Tilapia (GIFT, Oreochromis niloticus) under Global Warming
Effects of Ocean Acidification over successive generations decrease larval resilience to Ocean Acidification & Warming but juvenile European sea bass could benefit from higher temperatures in the NE Atlantic
Comparison of Metabolic Rates of Young of the Year Beluga (Huso huso), Sterlet (Acipenser ruthenus) and Bester Hybrid Reared in a Recirculating Aquaculture System
N-Acetylcysteine and cysteamine bitartrate prevent azide-induced neuromuscular decompensation by restoring glutathione balance in two novel surf1−/− zebrafish deletion models of Leigh syndrome
Chronic impact of exposure to low dissolved oxygen on the physiology of Dicentrarchus labrax and Sparus aurata and its effects on the acute stress response
Significance of sea entry pathway of chum salmon Oncorhynchus keta fry, inferred from the differential expressions of Na+, K+-ATPase α-subunit genes in the gills
Better together: cross-tolerance induced by warm acclimation and nitrate exposure improved the aerobic capacity and stress tolerance of common carp Cyprinus carpio
The interactive effects of exercise training and functional feeds on the cardiovascular performance of rainbow trout (Oncorhynchus mykiss) at high temperatures
Muscle fiber plasticity, stress physiology, and muscle transcriptome determine the inter-individual difference of swimming performance in the large yellow croaker (Larimichthys crocea)
How does induced polyploidy affect the swimming and physiological performance of juvenile sterlet (Acipenser ruthenus) and Siberian sturgeon (Acipenser baerii) and their reciprocal hybrids?
Maturation and spawning performance of hormonally-induced precocious female barramundi (Lates calcarifer) and implications of their use in selective breeding
Microplastics can aggravate the impact of ocean acidification on the health of mussels: Insights from physiological performance, immunity and byssus properties
Dietary exposure to environmentally relevant pesticide mixtures impairs swimming performance and lipid homeostatic gene expression in Juvenile Chinook salmon at elevated water temperatures
Can short-term data accurately model long-term environmental exposures? Investigating the multigenerational adaptation potential of Daphnia magna to environmental concentrations of organic ultraviolet filters
Synthesized effects of medium-term exposure to seawater acidification and microplastics on the physiology and energy budget of the thick shell mussel Mytilus coruscus
Induced sustained swimming modifies the external morphology, increasing the oxygen-carrying capacity and plasma lactate levels of juvenile gilthead seabream (Sparus aurata) without changing fish performance or skeletal muscle characteristics
The individuality affects the hormone secretion of the caudal neurosecretory system (CNSS) and correlation with respiratory metabolism, spontaneous activity and appetite in olive flounder (Paralichthys olivaceus)
Physiological responses of the upside-down jellyfish, Cassiopea (Cnidaria: Scyphozoa: Cassiopeidae) to temperature and implications for their range expansion along the east coast of Australia
Latent impacts on juvenile rainbow trout (Oncorhynchus mykiss) cardio-respiratory function and swimming performance following embryonic exposures to hydraulic fracturing flowback and produced water
Impact of heatwaves and environmental ammonia on energy metabolism, nitrogen excretion, and mRNA expression of related genes in the indicator model system Daphnia magna
Does the ventricle limit cardiac contraction rate in the anoxic turtle (Trachemys scripta)? I. Comparison of the intrinsic contractile responses of cardiac chambers to the extracellular changes that accompany prolonged anoxia exposure
Social influence on anti-predatory behaviors of juvenile bighead carp (Hypophthalmichthys nobilis) are influenced by conspecific experience and shoal composition
Continuous-Flow Magnetic Fractionation of Red Blood Cells Based on Hemoglobin Content and Oxygen Saturation—Clinical Blood Supply Implications and Sickle Cell Anemia Treatment
Can slowing the rate of water temperature decline be utilized to reduce the impacts of cold water pollution from dam releases on fish physiology and performance?
Interacting climate change effects on mussels (Mytilus edulis and M. galloprovincialis) and oysters (Crassostrea gigas and Ostrea edulis): experiments for bivalve individual growth models
Hypoxia tolerance in two amazon cichlids: mitochondrial respiration and cellular metabolism adjustments are result of species environmental preferences and distribution
Differences in external morphology, body composition and swimming performance between hatchery-and wild-origin marbled rockfish (Sebastiscus marmoratus)
Austad, Steven N; Buford, Thomas W; Allison, David B; Ballinger, Scott; Brown, Andrew W; Carter, Christy S; Darley-Usmar, Victor M; Hartman, John L; Nagy, Timothy R; Smith, Daniel L; (2021)
Indirect evidence that anoxia exposure and cold acclimation alter transarcolemmal Ca2+ flux in the cardiac pacemaker, right atrium and ventricle of the red-eared slider turtle (Trachemys scripta)
Adrenergically induced translocation of red blood cell β-adrenergic sodium-proton exchangers has ecological relevance for hypoxic and hypercapnic white seabass
Metabolic performance and thermal preference of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi and non-native trout across an ecologically relevant range of temperatures
Plasticity in standard and maximum aerobic metabolic rates in two populations of an Estuarine dependent teleost, spotted Seatrout (Cynoscion nebulosus)
Fish specialize their metabolic performance to maximize bioenergetic efficiency in their local environment: conspecific comparison between two stocks of Pacific chub mackerel (Scomber japonicus)
Physiological trade-offs associated with fasting weight loss, resistance to exercise and behavioral traits in farmed gilthead sea bream (Sparus aurata) selected by growth
Thermal tolerance and routine oxygen consumption of convict cichlid, Archocentrus nigrofasciatus, acclimated to constant temperatures (20° C and 30° C) and a daily temperature cycle (20° C→ 30° C)
Effects of temperature on hatching and growth performance of embryos and yolk-sac larvae of a threatened estuarine fish: Longfin smelt (Spirinchus thaleichthys)
Comparative swimming performance and behaviour of three benthic fish species: The invasive round goby (Neogobius melanostomus), the native bullhead (Cottus gobio), and the native gudgeon (Gobio gobio)
Effect of increased embryonic temperature during developmental windows on survival, morphology and oxygen consumption of rainbow trout (Oncorhynchus mykiss)
Influence of prey condition and incubation method on mortality, growth and metabolic rate during early life history in lake sturgeon, Acipenser fulvescens
Physiological insights for aquaculture diversification: Swimming capacity and efficiency, and metabolic scope for activity in cojinoba Seriolella violacea
Environmentally relevant concentrations of boscalid exposure affects the neurobehavioral response of zebrafish by disrupting visual and nervous systems
Experimental copper exposure, but not heat stress, leads to elevated intraovarian thyroid hormone levels in three-spined sticklebacks (Gasterosteus aculeatus)
Laboratory trials to evaluate carbon dioxide as a potential behavioral control method for invasive red swamp (Procambarus clarkii) and rusty crayfish (Faxonius rusticus)
From operculum and body tail movements to different coupling of physical activity and respiratory frequency in farmed gilthead sea bream and European sea bass. Insights on aquaculture biosensing
Physiological limits to inshore invasion of Indo-Pacific lionfish (Pterois spp.): insights from the functional characteristics of their visual system and hypoxia tolerance
Changes in heat stress tolerance in a freshwater amphipod following starvation: The role of oxygen availability, metabolic rate, heat shock proteins and energy reserves
Measuring maximum oxygen uptake with an incremental swimming test and by chasing rainbow trout to exhaustion inside a respirometry chamber yields the same results
Long-term exposure to low 17α-ethinylestradiol (EE2) concentrations disrupts both the reproductive and the immune system of juvenile rainbow trout, Oncorhynchus mykiss
Polyvinylpyrolidone-functionalized silver nanoparticles do not affect aerobic performance or fractional rates of protein synthesis in rainbow trout (Oncorhynchus mykiss)
Behrens, Jane W; von Friesen, Lisa W; Brodin, Tomas; Ericsson, Philip; Hirsch, Philipp Emanuel; Persson, Anders; Sundelin, Anna; van Deurs, Mikael; Nilsson, P Anders; (2020)
Risk-taking and locomotion in foraging threespine sticklebacks (Gasterosteus aculeatus): the effect of nutritional stress is dependent on social context
Effect of acclimation temperature on thermoregulatory behaviour, thermal tolerance and respiratory metabolism of Lutjanus guttatus and the response of heat shock protein 70 (Hsp70) and lactate dehydrogenase (Ldh‐a) genes
The impacts of increasing temperature and moderate hypoxia on the production characteristics, cardiac morphology and haematology of Atlantic Salmon (Salmo salar)
Effects of food deprivation on plasma insulin-like growth factor-1 (Igf1) and Igf binding protein (Igfbp) gene transcription in juvenile cabezon (Scorpaenichthys marmoratus)
Hamilton, Scott L; Kashef, Neosha S; Stafford, David M; Mattiasen, Evan G; Kapphahn, Lauren A; Logan, Cheryl A; Bjorkstedt, Eric P; Sogard, Susan M; (2019)
Journal of Experimental Marine Biology and Ecology
Evaluation of the i-STAT (portable clinical analyser) for measuring haematological parameters in Atlantic cod (Gadus morhua) at different CO 2 and temperature conditions
Independent and Interactive Effects of Long-Term Exposure to Hypoxia and Elevated Water Temperature on Behavior and Thermal Tolerance of an Equatorial Cichlid
The effects of repeat acute thermal stress on the critical thermal maximum (CTmax) and physiology of juvenile shortnose sturgeon Acipenser brevirostrum
Physiological trade-offs, acid-base balance and ion-osmoregulatory plasticity in European sea bass (Dicentrarchus labrax) juveniles under complex scenarios of salinity variation, ocean acidification and high ammonia challenge
Combined effects of ocean acidification and temperature on larval and juvenile growth, development and swimming performance of European sea bass (Dicentrarchus labrax)
Impact of the replacement of dietary fish oil by animal fats and environmental salinity on the metabolic response of European Seabass (Dicentrarchus labrax)
Differences in swimming performance and energetic costs between an endangered native toothcarp (Aphanius iberus) and an invasive mosquitofish (Gambusia holbrooki)
Treatment with Nitrate, but Not Nitrite, Lowers the Oxygen Cost of Exercise and Decreases Glycolytic Intermediates While Increasing Fatty Acid Metabolites in Exercised Zebrafish
Axton, Elizabeth R; Beaver, Laura M; St Mary, Lindsey; Truong, Lisa; Logan, Christiana R; Spagnoli, Sean; Prater, Mary C; Keller, Rosa M; Garcia-Jaramillo, Manuel; Ehrlicher, Sarah E; (2019)
Gleiss, Adrian C; Dale, Jonathan J; Klinger, Dane H; Estess, Ethan E; Gardner, Luke D; Machado, Benjamin; Norton, Alexander G; Farwell, Charles; Block, Barbara A; (2019)
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology
The effects of salinity and photoperiod on aerobic scope, hypoxia tolerance and swimming performance of coho salmon (Oncorhynchus kisutch) reared in recirculating aquaculture systems
Physiological performance of ballan wrasse (Labrus bergylta) at different temperatures and its implication for cleaner fish usage in salmon aquaculture
Metabolic rates from Bluntnose minnow (Pimephales notatus) populations at lower latitudes are more sensitive to changes in temperature than populations at higher latitudes
Thermal preference, tolerance, and thermal aerobic scope in clownfish Amphiprion ocellaris (Cuvier, 1830) predict its aquaculture potential across tropical regions
Velasco-Blanco, Gabriela; Re, Ana Denise; Díaz, Fernando; Ibarra-Castro, Leonardo; Abdo-de la Parra, Maria Isabel; Rodríguez-Ibarra, Luz Estela; Rosas, Carlos; (2019)
Turner, Ashley N; Hoffman, Jessica M; Powell, Mickie L; Sammy, Melissa J; Moellering, Douglas R; Nagy, Tim R; Austad, Steven N; Smith, Daniel L; (2019)
The Effect of Water Temperature, Angling Time, and Dissolved Oxygen on the Survival of Largemouth Bass Subjected to Simulated Angling and Tournament Handling Procedures
Mechanisms of toxic action of copper and copper nanoparticles in two Amazon fish species: Dwarf cichlid (Apistogramma agassizii) and cardinal tetra (Paracheirodon axelrodi)
Comparison of aerobic scope for metabolic activity in aquatic ectotherms with temperature related metabolic stimulation: a novel approach for aerobic power budget
Does hypoxia or different rates of re-oxygenation after hypoxia induce an oxidative stress response in Cyphocharax abramoides (Kner 1858), a Characid fish of the Rio Negro?
Nutritional physiology of mahi-mahi (Coryphaena hippurus): Postprandial metabolic response to different diets and metabolic impacts on swim performance
Metabolic rates and spontaneous swimming activity of two krill species (Euphausiacea) under different temperature regimes in the St. Lawrence Estuary, Canada
Exposure of European sea bass (Dicentrarchus labrax) to chemically dispersed oil has a chronic residual effect on hypoxia tolerance but not aerobic scope
Growth potential and habitat requirements of endangered age-0 pallid sturgeon (Scaphirhynchus albus) in the Missouri River, USA, determined using a individual-based model framework.
Knecht, Andrea L; Truong, Lisa; Marvel, Skylar W; Reif, David M; Garcia, Abraham; Lu, Catherine; Simonich, Michael T; Teeguarden, Justin G; Tanguay, Robert L; (2017)
How the expression of green fluorescent protein and human cardiac actin in the heart influences cardiac function and aerobic performance in zebrafish Danio rerio
Replacement of fishmeal with corn gluten meal in feeds for juvenile rainbow trout (Oncorhynchus mykiss) does not affect oxygen consumption during forced swimming
Permethrin alters glucose metabolism in conjunction with high fat diet by potentiating insulin resistance and decreases voluntary activities in female C57BL/6J mice
Hot or not? Comparative behavioral thermoregulation, critical temperature regimes, and thermal tolerances of the invasive lionfish Pterois sp. versus native western North Atlantic reef fishes
RNA-seq reveals a diminished acclimation response to the combined effects of ocean acidification and elevated seawater temperature in Pagothenia borchgrevinki.
The Effects of Sequential Environmental and Harvest Stressors on the Sensory Characteristics of Cultured Channel Catfish (Ictalurus Punctatus) Fillets.
Critical thermal maxima and hematology for juvenile Atlantic (Acipenser oxyrinchus Mitchill 1815) and shortnose (Acipenser brevirostrum Lesueur, 1818) sturgeons.
Difference in responses of two coastal species to fluctuating salinities and temperatures: Potential modification of specific distribution areas in the context of global change.
Differential abundance of muscle proteome in cultured channel catfish (Ictalurus punctatus) subjected to ante-mortem stressors and its impact on fillet quality.
Local adaptation to osmotic environment in killifish, Fundulus heteroclitus, is supported by divergence in swimming performance but not by differences in excess post-exercise oxygen consumption or aerobic scope.
Transcriptome wide analyses reveal a sustained cellular stress response in the gill tissue of Trematomus bernacchii after acclimation to multiple stressors.
Repeated evolution of local adaptation in swimming performance: population-level trade-offs between burst and endurance swimming in Brachyrhaphis freshwater fish.
Effects of dietary Gracilaria sp. and Alaria sp. supplementation on growth performance, metabolic rates and health in meagre (Argyrosomus regius) subjected to pathogen infection.
Partitioning the metabolic scope: the importance of anaerobic metabolism and implications for the oxygen- and capacity-limited thermal tolerance (OCLTT) hypothesis.
Combined effects of short-term exposure to elevated CO2 and decreased O2 on the physiology and energy budget of the thick Shell mussel Mytilus coruscus.
Measuring maximum and standard metabolic rates using intermittent-flow respirometry: a student laboratory investigation of aerobic metabolic scope and environmental hypoxia in aquatic breathers.
Behaviour in a standardized assay, but not metabolic or growth rate, predicts behavioural variation in an adult aquatic top predator Esox lucius in the wild.
Respiratory plasticity is insufficient to alleviate blood acid–base disturbances after acclimation to ocean acidification in the estuarine red drum, Sciaenops ocellatus.
Metabolic rate and thermal tolerance in two congeneric Amazon fishes: Paracheirodon axelrodi Schultz, 1956 and Paracheirodon simulans Ge´ry, 1963 (Characidae).
Repeated sublethal exposures to the sea lice pesticide Salmosan® (azamethiphos) on adult male lobsters (Homarus americanus) causes neuromuscular dysfunction, hypoxia, metabolic disturbances and mortality.
Hypoxia depresses CYP1A induction and enhances DNA damage, buth as minimal effects on antioxidant responses in sheepshead minnow (Cyprinodon variegatus) larvae exposed to dispersed crude oil.
Effects of Deepwater Horizon crude oil exposure, temperature and developmental stage on oxygen consumption of embryonic and larval mahi-mahi (Coryphaena hippurus).
Phenotypic variation in metabolism and morphology correlating with animal swimming activity in the wild: relevance for the OCLTT (oxygen- and capacity-limitation of thermal tolerance), allocation and performance models.
Maximal oxygen consumption increases with temperature in the European eel (Anguilla anguilla) through increased heart rate and arteriovenous extraction.
Do individual Activity Patterns of Brown Trout (Salmo trutta) alter the Exposure to Parasitic Freshwater Pearl Mussel (Margaritifera margaritifera) Larvae?
Metabolic fates and effects of nitrite in brown trout under normoxic and hypoxic conditions: blood and tissue nitrite metabolism and interactions with branchial NOS, Na+/K+-ATPase and hsp70 expression.
Interaction of osmoregulatory and acid-base compensation in white sturgeon (Acipenser transmontanus) during exposure to aquatic hypercarbia and elevated salinity.
Critical windows in embryonic development: Shifting incubation temperatures alter heart rate and oxygen consumption of Lake Whitefish (Coregonus clupeaformis) embryos and hatchlings.
The effects of chronic cadmium exposure on repeat swimming performance and anaerobic metabolism in brown trout (Salmo trutta) and lake whitefish (Coregonus clupeaformis).
Steelhead trout Oncorhynchus mykiss metabolic rate is affected by dietary Aloe vera inclusion but not by mounting an immune response against formalin-killed Aeromonas salmonicida.
Diets supplemented with seaweed affect metabolic rate, innate immune, and antioxidant responses, but not individual growth rate in European seabass (Dicentrarchus labrax).
At the edge of the thermal window: effects of elevated temperature on the resting metabolism, hypoxia tolerance and upper critical thermal limit of a widespread African cichlid.
Comparison of the acute effects of benzo-a-pyrene on adult zebrafish (Danio rerio) cardiorespiratory function following intraperitoneal injection versus aqueous exposure.
Embryonic critical windows: changes in incubation temperature alter survival, hatchling phenotype, and cost of development in lake whitefish (Coregonus clupeaformis)
Effects of diel temperature fluctuation on the standard metabolic rate of juvenile Atlantic salmon (Salmo salar): Influence of acclimation temperature and provenience.
Intraspecific variation in aerobic and anaerobic locomotion: gilthead sea bream (Sparus aurata) and Trinidadian guppy (Poecilia reticulata) do not exhibit a trade-off between maximum sustained swimming speed and minimum cost of transport.
9–28 d of exposure to elevated pCO2 reduces avoidance of predator odour but had no effect on behavioural lateralization or swimming activity in a temperate wrasse (Ctenolabrus rupestris).
Behavioural alterations from exposure to Cu, phenanthrene, and Cu-phenanthrene mixtures: linking behaviour to acute toxic mechanisms in the aquatic amphipod, Hyalella azteca.
Does the thermal plasticity of metabolic enzymes underlie thermal compensation of locomotor performance in the eastern newt (Notophthalmus viridescens)?
Anaemia only causes a small reduction in the upper critical temperature of sea bass: is oxygen delivery the limiting factor for tolerance of acute warming in fishes?
Swimming performance and larval quality are altered by rearing substrate at early life phases in white sturgeon, Acipenser transmontanus (Richardson, 1836).
In ovo exposure to selenomethionine via maternal transfer increases developmental toxicities and impairs swim performance in F1 generation zebrafish (Danio rerio).
Physiology and performance of wild and domestic strains of diploid and triploid rainbow trout (Oncorhynchus mykiss) in response to environmental challenges.
Evidence of Circadian Rhythm, Oxygen Regulation Capacity, Metabolic Repeatability and Positive Correlations between Forced and Spontaneous Maximal Metabolic Rates in Lake Sturgeon Acipenser fulvescens.
Cardiorespiratory responses of seawater-acclimated adult Arctic char (Salvelinus alpinus) and Atlantic salmon (Salmo salar) to an acute temperature increase.
Effect of plant proteins and crystalline amino acid supplementation on postprandial plasma amino acid profiles and metabolic response in rainbow trout (Oncorhynchus mykiss).
Northern shrimp (Pandalus borealis) oxygen consumption and metabolic enzyme activities are severely constrained by hypoxia in the Estuary and Gulf of St. Lawrence.
The Effect of Short-Duration Seawater Exposure and Acoustic Tag Implantation on the Swimming Performance and Physiology of Presmolt Juvenile Coho Salmon.
Swimming flumes as a tool for studying swimming behaviour and physiology: Current applications and future developments. Part IV, Chapter 15. pp 345-376. In: Swimming Physiology of Fish: Towards using exercise to farm a fit fish in sustainable aquaculture. Palstra and Planas (eds) 2013.
Practical aspects of induced exercise in finfish aquaculture. Part IV, pp 377-405. In: Swimming Physiology of Fish: Towards using exercise to farm a fit fish in sustainable aquaculture. Palstra and Planas (eds) 2013.
Effects of temperature on feed intake, growth and oxygen consumption in adult male king crab Paralithodes camtschaticus held in captivity and fed manufactured diets.
Effects of intraspecific variation in reproductive traits, pectoral fin use and burst swimming on metabolic rates and swimming performance: a study on the Trinidadian guppy (Poecilia reticulata Peters).
S. Schmeisser, K. Schmeisser, S. Weimer, M. Groth, S. Priebe, E. Fazius, D. Kuhlow, D. Pick, J. W. Einax, R. Guthke, M. Platzer, K. Zarse, M. Ristow (2013)
Blood oxygenation and cardiorespiratory function in steelhead trout (Oncorhynchus mykiss) challenged with an acute temperature increase and zatebradine-induced bradycardia.
Ontogenetic differentiation of swimming performance and behaviour in relation to habitat availability in the endangered North Sea houting (Coregonus oxyrinchus).
Comparison of oxygen consumption by Terebratalia transversa (Brachiopoda) and two species of pteriomorph bivalve molluscs: implications for surviving mass extinctions.
High latitude fish in a high CO2 world: Synergistic effects of elevated temperature and carbon dioxide on the metabolic rates of Antarctic nolothenioids.
Dietary supplementation of essential fatty acids in larval pikeperch (Sander lucioperca) short and long term effects on stress tolerance and metabolic physiology.
Preventative effects of conjugated linoleic acid on obesity by improved physical activity in nescient basic helix-loop-helix 2 knockout mice during growth period.
Plasma-accessible carbonic anhydrase at the tissue of a teleost fish may greatly enhance oxygen delivery: in vitro evidence in rainbow trout, Oncorhynchus mykiss.
Repeat Swimming Performance and Its Implications for Inferring the Relative Fitness of Asexual Hybrid Dace (Pisces: Phoxinus ) and Their Sexually Reproducing Parental Species.
J. Wang, D. Panáková, K. Kikuchi, J. E. Holdway, M. Gemberling, J. S. Burris, S. P. Singh, A. L. Dickson, Y. F. Lin, M. K. Sabeh, A. A. Werdich, D. Yelon, C. A. MacRae and K. D. Poss (2011)
Effects of nitrite exposure on functional haemoglobin levels, bimodal respiration, and swimming performance in the facultative air-breathing fish Pangasianodon hypophthalmus.
The effect of dietary fish oil and poultry fat replacement with canola oil on swimming performance and metabolic response to hypoxia in stream type spring Chinook salmon parr.
The intestinal response to feeding in seawater gulf toadfish, Opsanus beta, includes elevated base secretion and increased epithelial oxygen consumption.
Effects of feeding and hypoxia on cardiac performance and gastrointestinal blood flow during critical speed swimming in the sea bass Dicentrarchus labrax.
The relationship between caudal differential pressure and activity of Atlantic cod: a potential method to predict oxygen consumption of free-swimming fish.
The multiple responses of fishes to changes in dissolved oxygen saturations have been studied widely in the laboratory. In contrast, only a few studies have included field observa- tions. The objective of the present study was to evaluate the performance of a novel acoustic dissolved oxygen transmitter for field biotelemetry. The results demonstrated that the output of the transmitter was unaffected by three different temperatures (10 to 30°C) and described the dissolved oxygen saturation with high accuracy (r 2 > 0.99) over the entire range of 0 to 191% saturation. The response time (≥ 90% of end value) of the transmitter was 12 s both in terms of decreasing (100 to 0%) and increasing (0 to 100%) oxygen saturations. When externally attached to fishes, the present findings support the use of the transmitter for reliable dissolved oxygen measurements on individuals living in environments that may change both temporally and spatially with regard to ambient temperature and dissolved oxygen saturation.
Experience-Dependent Modulation of C. elegans Behavior by Ambient Oxygen.
To determine the energetic costs of rigid-body, median or paired-fin (MPF)swimming versus undulatory, body-caudal fin (BCF) swimming, we measured oxygen consumption as a function of swimming speed in two MPF swimming specialists, Schlegel's parrotfish and Picasso triggerfish. The parrotfish swam exclusively with the pectoral fins at prolonged swimming speeds up to 3.2 total lengths per second (L s-1; 30 min critical swimming speed, Ucrit). At higher speeds, gait transferred to a burst-and-coast BCF swimming mode that resulted in rapid fatigue. The triggerfish swam using undulations of the soft dorsal and anal fins up to 1.5 L s-1, beyond which BCF undulations were recruited intermittently. BCF swimming was used continuously above 3.5 L s-1, and was accompanied by synchronous undulations of the dorsal and anal fins. The triggerfish were capable of high, prolonged swimming speeds of up to 4.1 L s-1 (30 min Ucrit). In both species, the rates of increase in oxygen consumption with swimming speed were higher during BCF swimming than during rigid-body MPF swimming. Our results indicate that, for these species,undulatory swimming is energetically more costly than rigid-body swimming, and therefore support the hypothesis that MPF swimming is more efficient. In addition, use of the BCF gait at higher swimming speed increased the cost of transport in both species beyond that predicted for MPF swimming at the same speeds. This suggests that, unlike for terrestrial locomotion, gait transition in fishes does not occur to reduce energetic costs, but to increase recruitable muscle mass and propulsive surfaces. The appropriate use of the power and exponential functions to model swimming energetics is also discussed.
Effects of social and visual contact on the oxygen consumption of juvenile sea bass measured by computerized intermittent respirometry.
The resting metabolic rate (RMR) of juvenile European sea bass Dicentrarchus labrax L. (47·5±1·5 g, 15–18 cm) was 126·2±2·5 mgO 2 kg −1 h −1, and temporal patterns of oxygen consumption were not affcted by visual contact or social interaction with conspecifics. The results suggest that a group effect is not present in juvenile D. labrax, thus no selective advantage of shoaling is gained through lowered metabolism in this facultative schooling species.
Energy savings in sea bass swimming in a school: measurements of tail beat frequency and oxygen consumption at different swimming speeds
Tail beat frequency of sea bass, Dicentrarchus labrax (L.) (23.5 ± 0·5 cm, L T ), swimming at the front of a school was significantly higher than when swimming at the rear, for all water velocities tested from 14·8 to 32 cm s −1. The logarithm of oxygen consumption rate, and the tail beat frequency of solitary swimming sea bass (28·8 ± 0·4 cm, L T ), were each correlated linearly with swimming speed, and also with one another. The tail beat frequency of individual fish was 9–14% lower when at the rear of a school than when at the front, corresponding to a 9–23% reduction in oxygen consumption rate.