Posts Tagged 'fish'

Correlated effects of ocean acidification and warming on behavioral and metabolic traits of a large pelagic fish

Ocean acidification and warming are co-occurring stressors, yet their effects on early life stages of large pelagic fishes are not well known. Here, we determined the effects of elevated CO2 and temperature at levels projected for the end of the century on activity levels, boldness, and metabolic traits (i.e., oxygen uptake rates) in larval kingfish (Seriola lalandi), a large pelagic fish with a circumglobal distribution. We also examined correlations between these behavioral and physiological traits measured under different treatments. Kingfish were reared from the egg stage to 25 days post-hatch in a full factorial design of ambient and elevated CO2 (~500 µatm and ~1000 µatm) and temperature (21 °C and 25 °C). Activity levels were higher in fish from the elevated temperature treatment compared with fish reared under ambient temperature. However, elevated CO2 did not affect activity, and boldness was not affected by either elevated CO2 or temperature. Both elevated CO2 and temperature resulted in increased resting oxygen uptake rates compared to fish reared under ambient conditions, but neither affected maximum oxygen uptake rates nor aerobic scope. Resting oxygen uptake rates and boldness were negatively correlated under ambient temperature, but positively correlated under elevated temperature. Maximum oxygen uptake rates and boldness were also negatively correlated under ambient temperature. These findings suggest that elevated temperature has a greater impact on behavioral and physiological traits of larval kingfish than elevated CO2. However, elevated CO2 exposure did increase resting oxygen uptake rates and interact with temperature in complex ways. Our results provide novel behavioral and physiological data on the responses of the larval stage of a large pelagic fish to ocean acidification and warming conditions, demonstrate correlations between these traits, and suggest that these correlations could influence the direction and pace of adaptation to global climate change.

Continue reading ‘Correlated effects of ocean acidification and warming on behavioral and metabolic traits of a large pelagic fish’

Living in a high CO2 world: a global meta‐analysis shows multiple trait‐mediated fish responses to ocean acidification

Understanding how marine organisms will be affected by global change is of primary importance to ensure ecosystem functioning and nature contributions to people. This study meets the call for addressing how life‐history traits mediate effects of ocean acidification on fish. We built a database of overall and trait‐mediated responses of teleost fish to future CO2 levels by searching the scientific literature. Using a meta‐analytical approach, we investigated the effects of projected CO2 levels by IPCC for 2050–2070 and 2100 on fish eco‐physiology and behavior from 320 contrasts on 42 species, stemming from polar to tropical regions. Moreover, since organisms may experience a mosaic of carbonate chemistry in coastal environments (e.g., in estuaries, upwelling zones and intertidal habitats), which may have higher pCO2 values than open ocean waters, we assessed responses from additional 103 contrasts on 21 fish species using pCO2 levels well above IPCC projections. Under mid‐century and end‐of‐century CO2 emission scenarios, we found multiple CO2‐dose‐dependent effects on calcification, resting metabolic rate, yolk, and behavioral performances, along with increased predation risk and decreased foraging, particularly for larvae. Importantly, many of the traits considered will not confer fish tolerance to elevated CO2 and far‐reaching ecological consequences on fish population replenishment and community structure will likely occur. Extreme CO2 levels well above IPCC projections showed effects on fish mortality and calcification, while growth, metabolism, and yolk were unaffected. CO2 exposures in short‐term experiments increased fish mortality, which in turn decreased in longer‐term exposures. Whatever the elevated CO2 levels considered, some key biological processes (e.g., reproduction, development, habitat choice) were critically understudied. Fish are an important resource for livelihoods in coastal communities and a key component for stability of marine ecosystems. Given the multiple trait‐mediated effects evidenced here, we stress the need to fill the knowledge gap on important eco‐physiological processes and to expand the number and duration of ocean acidification studies to multi‐generational, multiple stressor (e.g., warming, hypoxia, fishing), and species interactions experiments to better elucidate complex ecosystem‐level changes and how these changes might alter provisioning of ecosystem services.

Continue reading ‘Living in a high CO2 world: a global meta‐analysis shows multiple trait‐mediated fish responses to ocean acidification’

Temperature, acidification, and food supply interact to negatively affect the growth and survival of the forage fish, Menidia beryllina (Inland Silverside), and Cyprinodon variegatus (Sheepshead Minnow)

Climate change processes are warming, acidifying, and promoting a reduction of plankton biomass within World oceans. While the effects of these stressors on marine fish have been studied individually, their combined and interactive impacts remain unclear. Here we present experiments investigating the interactive effects of increased pCO2, temperature, and food-limitation on the early life history traits of two species of marine schooling fish native to Northeast US estuaries, Menidia beryllina (inland silverside) and Cyprinodon variegatus (sheepshead minnow). While each stressor significantly altered hatching times, growth rates, and/or survival of fish, significant interactions between stressors resulted in impacts that could not have been predicted based upon exposures to individual stressors. Fish that were unaffected by high pCO2 when reared at ideal temperatures experienced significant declines in survivorship when exposed to elevated pCO2 at temperatures above or below their thermal optimum. Similarly, fish provided with less food were more vulnerable to elevated pCO2 than fish provided with adequate nutrition. These findings highlight the significance of incorporating multiple stressors in studies investigating the impacts of climate change stressors on marine life. Collectively, these results suggest that climate change stressors may interact to synergistically suppress the productivity of fisheries in coastal ecosystems and that these effects may intensify as climate changes continue.

Continue reading ‘Temperature, acidification, and food supply interact to negatively affect the growth and survival of the forage fish, Menidia beryllina (Inland Silverside), and Cyprinodon variegatus (Sheepshead Minnow)’

Behavioral lateralization and scototaxis unaltered by near future ocean acidification conditions in Poecilia latipinna (Sailfin Molly)

Objective: Rising anthropogenic emissions of CO2 have increased ocean acidity by 25% (EPA, 2016).

Background: ). In more than 40 studies to date, this increase in CO2 has been shown to alter behaviors such as behavioral lateralization, the tendency of an individual to favor one side of the body, and scototaxis, light/dark preference, in fish. Scototaxis is a proxy for anxiety measurements.

Design/Methods The underlying cause of these behavioral disruptions is hypothesized to be caused by alterations of ion gradients across the GABAA receptor, the major inhibitory neurotransmitter found throughout the vertebrate nervous system. This study examined the effects of predicted nearfuture CO2 concentrations (~1000 ?atm) on behavioral lateralization and scototaxis of Sailfin Molly (Poecilia latipinna).

Results: Elevated CO2 levels were not found to affect these behaviors in this understudied species. This study is one of the few to examine CO2-induced behavioral alterations in an estuarine species.

Conclusions: Findings from this study suggest Sailfin Molly could be more resilient to high CO2 levels than other tested species, however more research is needed to fully assess behavioral tolerance. These novel findings may inspire the field to understand the mechanisms leading to species specific differences in behavioral tolerance, potentially allowing for better assessment of adaptive capacity.

Continue reading ‘Behavioral lateralization and scototaxis unaltered by near future ocean acidification conditions in Poecilia latipinna (Sailfin Molly)’

Differential behavioural responses to venlafaxine exposure route, warming and acidification in juvenile fish (Argyrosomus regius)


• Warming and acidification enhanced VFX bioaccumulation in fish plasma.
• VFX triggered fish exploration, but reduced fish activity and shoal cohesion.
• Altered temperature and pH reduced shoal cohesion regardless of VFX exposure.
• Acidification plus VFX exposure reduced fish side preference.


Antidepressants, such as venlafaxine (VFX), which are considered emerging environmental pollutants, are increasingly more present in the marine environment, and recent evidence suggest that they might have adverse effects on fish behaviour. Furthermore, altered environmental conditions associated to climate change (e.g. warming and acidification) can also have a determinant role on fish behaviour, fitness and survival. Yet, the underlying interactions between these environmental stressors (pharmaceuticals exposure and climate change) are still far from being fully understood. The aim of this study was to assess behavioural responses (in juvenile meagre (Argyrosomus regius) exposed to VFX via water ([VFX] ~20 μg L−1) and via dietary sources ([VFX] ~160 μg kg−1 dry weight), as well as to increased temperature (ΔT°C = +5 °C) and high CO2 levels (ΔpCO2 ~1000 μatm; equivalent to ΔpH = −0.4 units). Overall, VFX bioaccumulation in fish plasma was enhanced under the combination of warming and acidification. VFX triggered fish exploration, whereas fish activity and shoal cohesion were reduced. Acidification alone decreased fish exploration and shoal cohesion, and reversed fish preference to turn leftwards compared to control conditions. Such alterations were further enhanced by VFX exposure. The combination of warming and acidification also reduced shoal cohesion and loss of lateralization, regardless of VFX exposure. The distinct behaviour observed when VFX contamination, acidification and warming acted alone or in combination highlighted the need to consider the likely interactive effects of seawater warming and acidification in future research regarding the toxicological aspects of chemical contaminants.

Continue reading ‘Differential behavioural responses to venlafaxine exposure route, warming and acidification in juvenile fish (Argyrosomus regius)’

On the wrong track: ocean acidification attracts larval fish to irrelevant environmental cues

Population replenishment of marine life largely depends on successful dispersal of larvae to suitable adult habitat. Ocean acidification alters behavioural responses to physical and chemical cues in marine animals, including the maladaptive deterrence of settlement-stage larval fish to odours of preferred habitat and attraction to odours of non-preferred habitat. However, sensory compensation may allow fish to use alternative settlement cues such as sound. We show that future ocean acidification reverses the attraction of larval fish (barramundi) to their preferred settlement sounds (tropical estuarine mangroves). Instead, acidification instigates an attraction to unfamiliar sounds (temperate rocky reefs) as well as artificially generated sounds (white noise), both of which were ignored by fish living in current day conditions. This finding suggests that by the end of the century, following a business as usual CO2 emission scenario, these animals might avoid functional environmental cues and become attracted to cues that provide no adaptive advantage or are potentially deleterious. This maladaptation could disrupt population replenishment of this and other economically important species if animals fail to adapt to elevated CO2 conditions.

Continue reading ‘On the wrong track: ocean acidification attracts larval fish to irrelevant environmental cues’

Effect of elevated CO2 and small boat noise on the kinematics of predator–prey interactions

Oceans of the future are predicted to be more acidic and noisier, particularly along the productive coastal fringe. This study examined the independent and combined effects of short-term exposure to elevated CO2 and boat noise on the predator–prey interactions of a pair of common coral reef fishes (Pomacentrus wardi and its predator, Pseudochromis fuscus). Successful capture of prey by predators was the same regardless of whether the pairs had been exposed to ambient control conditions, the addition of either playback of boat noise, elevated CO2 (925 µatm) or both stressors simultaneously. The kinematics of the interaction were the same for all stressor combinations and differed from the controls. The effects of CO2 or boat noise were the same, suggesting that their effects were substitutive in this situation. Prey reduced their perception of threat under both stressors individually and when combined, and this coincided with reduced predator attack distances and attack speeds. The lack of an additive or multiplicative effect when both stressors co-occurred was notable given the different mechanisms involved in sensory disruptions and highlights the importance of determining the combined effects of key drivers to aid in predicting community dynamics under future environmental scenarios.

Continue reading ‘Effect of elevated CO2 and small boat noise on the kinematics of predator–prey interactions’

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Ocean acidification in the IPCC AR5 WG II

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