Posts Tagged 'fish'

Climate change does not affect seafood quality of a common targeted fish

Climate change can affect marine and estuarine fish via alterations to their distributions, abundances, sizes, physiology and ecological interactions, threatening the provision of ecosystem goods and services. While we have an emerging understanding of such ecological impacts to fish, we know little about the potential influence of climate change on the provision of nutritional seafood to sustain human populations. In particular, the quantity, quality and/or taste of seafood may be altered by future environmental changes with implications for the economic viability of fisheries. In an orthogonal mesocosm experiment, we tested the influence of near‐future ocean warming and acidification on the growth, health and seafood quality of a recreationally and economically important fish, yellowfin bream (Acanthopagrus australis). The growth of yellowfin bream significantly increased under near‐future temperature conditions (but not acidification), with little change in health (blood glucose and haematocrit) or tissue biochemistry and nutritional properties (fatty acids, lipids, macro‐and micronutrients, moisture, ash, and total N). Yellowfin bream appear to be highly resilient to predicted near‐future ocean climate change, which might be facilitated by their broad spatio‐temporal distribution across habitats and broad diet. Moreover, an increase in growth, but little change in tissue quality, suggests that near‐future ocean conditions will benefit fisheries and fishers that target yellowfin bream. The data reiterate the inherent resilience of yellowfin bream as an evolutionary consequence of their euryhaline status in often environmentally challenging habitats, and imply their sustainable and viable fisheries into the future.We contend that widely‐distributed species that span large geographic areas and habitats can be “climate‐winners” by being resilient to negative direct impacts of near‐future oceanic and estuarine climate change.
Continue reading ‘Climate change does not affect seafood quality of a common targeted fish’

Living in a multi-stressors environment: an integrated biomarker approach to assess the ecotoxicological response of meagre (Argyrosomus regius) to venlafaxine, warming and acidification

• VFX toxicity was influenced by exposure route, as well as by abiotic stressors
• VFX water exposure induced more severe biomarker responses than VFX feed exposure
• Muscle, liver and brain biomarker responses were significantly affected by warming
• Biomarker changes due to acidification were more evident in fish gills
• The combination of the three stressors simultaneously increased stress severity
• The importance of assessing potential interaction between stressors was evidenced

Pharmaceuticals, such as the antidepressant venlafaxine (VFX), have been frequently detected in coastal waters and marine biota, and there is a growing body of evidence that these pollutants can be toxic to non-target marine biota, even at low concentrations. Alongside, climate change effects (e.g. warming and acidification) can also affect marine species’ physiological fitness and, consequently, compromising their ability to cope with the presence of pollutants. Yet, information regarding interactive effects between pollutants and climate change-related stressors is still scarce. Within this context, the present study aims to assess the differential ecotoxicological responses (antioxidant activity, heat shock response, protein degradation, endocrine disruption and neurotoxicity) of juvenile fish (Argyrosomus regius) tissues (muscle, gills, liver and brain) exposed to VFX (via water or feed), as well as to the interactive effects of warming (ΔT°C = +5 °C) and acidification (ΔpCO2 ~ +1000 µatm, equivalent to ΔpH = −0.4 units), using an integrated multi-biomarker response (IBR) approach.

Overall, results showed that VFX toxicity was strongly influenced by the uptake pathway, as well as by warming and acidification. More significant changes (e.g. increases surpassing 100% in lipid peroxidation, LPO, heat shock response protein content, HSP70/HSC70, and total ubiquitin content, Ub,) and higher IBR index values were observed when VFX exposure occurred via water (i.e. average IBR = 19, against 17 in VFX-feed treatment). The co-exposure to climate change-related stressors either enhanced (e.g. glutathione S-transferases activity (GST) in fish muscle was further increased by warming) or attenuated the changes elicited by VFX (e.g. vitellogenin, VTG, liver content increased with VFX feed exposure acting alone, but not when co-exposed with acidification). Yet, increased stress severity was observed when the three stressors acted simultaneously, particularly in fish exposed to VFX via water (i.e. average IBR = 21). Hence, the distinct fish tissues responses elicited by the different scenarios emphasized the relevance of performing multi-stressors ecotoxicological studies, as such approach enables a better estimation of the environmental hazards posed by pollutants in a changing ocean and, consequently, the development of strategies to mitigate them.

Continue reading ‘Living in a multi-stressors environment: an integrated biomarker approach to assess the ecotoxicological response of meagre (Argyrosomus regius) to venlafaxine, warming and acidification’

Effects of ocean acidification on salinity tolerance and seawater growth of Atlantic salmon Salmo salar smolts

Human activity has resulted in increasing atmospheric carbon dioxide (CO2), which will result in reduced pH and higher levels of CO2 in the ocean, a process known as ocean acidification. Understanding the effects of ocean acidification (OA) on fishes will be important to predicting and mitigating its consequences. Anadromous species such as salmonids may be especially at risk because of their rapid movements between fresh water and seawater, which could minimize their ability to acclimate. In the present study, we examine the effect of future OA on the salinity tolerance and early seawater growth of Atlantic salmon Salmo salar smolts. Exposure to 610 and 1010 μatm CO2 did not alter salinity tolerance but did result in slightly lower plasma chloride levels in smolts exposed to seawater compared with controls (390 μatm). Gill Na+–K+‐ATPase activity, plasma cortisol, glucose and haematocrit after seawater exposure were not altered by elevated CO2. Growth rate in the first 2 weeks of seawater exposure was greater at 1010 μatm CO2 than under control conditions. This study of the effects of OA on S. salar during the transition from fresh water to seawater indicates that elevated CO2 is not likely to affect osmoregulation negatively and may improve early growth in seawater.

Continue reading ‘Effects of ocean acidification on salinity tolerance and seawater growth of Atlantic salmon Salmo salar smolts’

Predator avoidance in the European Seabass after recovery from short-term hypoxia and different CO2 conditions

Short-term hypoxia that lasts just a few days or even hours is a major threat for the marine ecosystems. The single effect of the human-induced levels of hypoxia and other anthropogenic impacts such as elevated pCO2 can reduce the ability of preys to detect their predators across taxa. Moreover, both processes, hypoxia and elevated pCO2, are expected to co-occur in certain habitats, but the synergic consequences of both processes and the ability of fish to recover remain unknown. To provide empirical evidence to this synergy, we experimentally evaluated the risk-taking behavior in juveniles of the European seabass (Dicentrachus labrax), an important commercial fisheries species after recovering from short-term hypoxia and different pH scenarios. The behavior of seabass juveniles was monitored in an experimental arena before and after the exposure to a simulated predator and contrasted to control fish (BACI design) (current levels of hypoxia and elevated pCO2) using a mechanistic function-valued modeling trait approach. Results revealed that fish recovering from elevated pCO2, alone or combined with hypoxia, presented less avoidance behavior in failing to seek refuge when a simulated predator was present in the arena compared to those exposed to control pCO2 levels. Our results show that recovery from short-term exposure to acidification and hypoxia was not synergistic and suggest that recovery from acidification takes longer than from short-term hypoxia treatment through a potential effect on the sensorial and hence behavioral capacities of fish.

Continue reading ‘Predator avoidance in the European Seabass after recovery from short-term hypoxia and different CO2 conditions’

Effects of seawater pH on survival, growth, energy budget and oxidative stress parameters of juvenile turbot Scophthalmus maximus

This study aimed to elucidate the influence of environment pH on survival, growth, energy allocation and oxidative damage of juvenile Scophthalmus maximus (19.89±0.25 g). Six pH treatments (6.3±0.2、6.8±0.2、7.3±0.2、7.8±0.2、8.3±0.2、8.8±0.2) lasting for eight weeks were included. Measurements of survival (SR), feed conversion ratio (FCR), specific growth rate (SGR), weight gain rate (WGR), energy allocation, liver superoxide dismutase activity (SOD), catalase activity (CAT), and malondialdehyde concentration (MDA) were done. Results show that SR did not vary from pH 6.3 to 7.8, but reduced then significantly (P < 0.05); FCR raised remarkably (P < 0.05) while SGR and WGR decreased pronouncedly (P < 0.05). Most of the food energy was used in metabolism, followed by growth, feces loss and nitrogenous excretion. Energy deposited for growth showed a decreasing tendency when pH raised; while for metabolism showed a reverse trend. SOD showed insignificant difference from pH 6.3 to 7.8, but the activities then elevated obviously (P 0.05). CAT kept stable between pH 6.3 and 7.3, then sharply increased (P 0.05). Subsequent decrease in MDA was found from pH 6.3 to 8.3 then the concentration smoothly increased. Overall, our results indicate that a pH in the range of 6.8 to 7.8 is recommended in the growth environment in cultivation of juvenile turbot.

Continue reading ‘Effects of seawater pH on survival, growth, energy budget and oxidative stress parameters of juvenile turbot Scophthalmus maximus’

Impact of ocean acidification and warming on the bioenergetics of developing eggs of Atlantic herring Clupea harengus

Atlantic herring (Clupea harengus) is a benthic spawner, therefore its eggs are prone to encounter different water conditions during embryonic development, with bottom waters often depleted of oxygen and enriched in CO2. Some Atlantic herring spawning grounds are predicted to be highly affected by ongoing Ocean Acidification and Warming with water temperature increasing by up to +3°C and CO2 levels reaching ca. 1000 μatm (RCP 8.5). Although many studies investigated the effects of high levels of CO2 on the embryonic development of Atlantic herring, little is known about the combination of temperature and ecologically relevant levels of CO2. In this study, we investigated the effects of Ocean Acidification and Warming on embryonic metabolic and developmental performance such as mitochondrial function, respiration, hatching success (HS) and growth in Atlantic herring from the Oslo Fjord, one of the spawning grounds predicted to be greatly affected by climate change. Fertilized eggs were incubated under combinations of two PCO2 conditions (400 μatm and 1100 μatm) and three temperatures (6, 10 and 14°C), which correspond to current and end-of-the-century conditions. We analysed HS, oxygen consumption (MO2) and mitochondrial function of embryos as well as larval length at hatch. The capacity of the electron transport system (ETS) increased with temperature, reaching a plateau at 14°C, where the contribution of Complex I to the ETS declined in favour of Complex II. This relative shift was coupled with a dramatic increase in MO2 at 14°C. HS was high under ambient spawning conditions (6–10°C), but decreased at 14°C and hatched larvae at this temperature were smaller. Elevated PCO2 increased larval malformations, indicating sub-lethal effects. These results indicate that energetic limitations due to thermally affected mitochondria and higher energy demand for maintenance occur at the expense of embryonic development and growth.

Continue reading ‘Impact of ocean acidification and warming on the bioenergetics of developing eggs of Atlantic herring Clupea harengus’

Projected amplification of food web bioaccumulation of MeHg and PCBs under climate change in the Northeastern Pacific

Climate change increases exposure and bioaccumulation of pollutants in marine organisms, posing substantial ecophysiological and ecotoxicological risks. Here, we applied a trophodynamic ecosystem model to examine the bioaccumulation of organic mercury (MeHg) and polychlorinated biphenyls (PCBs) in a Northeastern Pacific marine food web under climate change. We found largely heterogeneous sensitivity in climate-pollution impacts between chemicals and trophic groups. Concentration of MeHg and PCBs in top predators, including resident killer whales, is projected to be amplified by 8 and 3%, respectively, by 2100 under a high carbon emission scenario (Representative Concentration Pathway 8.5) relative to a no-climate change control scenario. However, the level of amplification increases with higher carbon emission scenario for MeHg, but decreases for PCBs. Such idiosyncratic responses are shaped by the differences in bioaccumulation pathways between MeHg and PCBs, and the modifications of food web dynamics between different levels of climate change. Climate-induced pollutant amplification in mid-trophic level predators (Chinook salmon) are projected to be higher (~10%) than killer whales. Overall, the predicted trophic magnification factor is ten-fold higher in MeHg than in PCBs under high CO2 emissions. This contribution highlights the importance of understanding the interactions with anthropogenic organic pollutants in assessing climate risks on marine ecosystems.

Continue reading ‘Projected amplification of food web bioaccumulation of MeHg and PCBs under climate change in the Northeastern Pacific’

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Ocean acidification in the IPCC AR5 WG II

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