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

Organ health and development in larval kingfish are unaffected by ocean acidification and warming

Anthropogenic CO₂ emissions are causing global ocean warming and ocean acidification. The early life stages of some marine fish are vulnerable to elevated ocean temperatures and CO₂ concentrations, with lowered survival and growth rates most frequently documented. Underlying these effects, damage to different organs has been found as a response to elevated CO₂ in larvae of several species of marine fish, yet the combined effects of acidification and warming on organ health are unknown. Yellowtail kingfish, Seriola lalandi, a circumglobal subtropical pelagic fish of high commercial and recreational value, were reared from fertilization under control (21 °C) and elevated (25 °C) temperature conditions fully crossed with control (500 µatm) and elevated (1,000 µatm) pCO₂ conditions. Larvae were sampled at 11 days and 21 days post hatch for histological analysis of the eye, gills, gut, liver, pancreas, kidney and liver. Previous work found elevated temperature, but not elevated CO₂, significantly reduced larval kingfish survival while increasing growth and developmental rate. The current histological analysis aimed to determine whether there were additional sublethal effects on organ condition and development and whether underlying organ damage could be responsible for the documented effects of temperature on survivorship. While damage to different organs was found in a number of larvae, these effects were not related to temperature and/or CO₂ treatment. We conclude that kingfish larvae are generally vulnerable during organogenesis of the digestive system in their early development, but that this will not be exacerbated by near-future ocean warming and acidification

Introduction

Contemporary culture is currently characterised by distinct movements both from within and without universities which are questioning, rethinking, and rewriting the parameters and ground of traditional academic disciplines. Law/Text/Culture situates itself within this mobile and changing cultural context; it seeks to enable the articulation of the issues and development of the theories and practices generated by disciplinary crossings between fields and bodies of knowledge that have traditionally been seen as discrete and autonomous. Law/Text/Culture is a journal committed to producing intersections of the law, textuality and all aspects of culture. It publishes work across a range of genres - from artwork to the traditional scholarly essay. It invites work which crosses borders - of genres and institutions, as well as disciplines and fields. The journal accepts work from people working outside and inside traditional educational and legal settings. Law/Text/Culture is particularly concerned with both the law\u27s textuality, that is, the specific textual forms by which the law circulates within a culture, and also the multiplicity of texts and subjects which the law touches and shapes, and which, in turn, impact on and change the law. This differentiates Law/Text/Culture from other interdisciplinary journals devoted to the fields of law and the humanities and law and literature

Elevated temperature and CO₂ have positive effects on the growth and survival of larval Australasian snapper

Rising water temperature and increased uptake of CO2 by the ocean are predicted to have widespread impacts on marine species. However, the effects are likely to vary, depending on a species’ sensitivity and the geographical location of the population. Here, we investigated the potential effects of elevated temperature and pCO2 on larval growth and survival in a New Zealand population of the Australasian snapper, Chrysophyrs auratus. Eggs and larvae were reared in a fully cross-factored experiment (18 °C and 22 °C/pCO2 440 and 1040 μatm) to 16 days post hatch (dph). Morphologies at 1 dph and 16 dph were significantly affected by temperature, but not CO2. At 1dph, larvae at 22 °C were longer (7%) and had larger muscle depth at vent (14%), but had reduced yolk (65%) and oil globule size (16%). Reduced yolk reserves in recently hatched larvae suggests higher metabolic demands in warmer water. At 16 dph, larvae at elevated temperature were longer (12%) and muscle depth at vent was larger (64%). Conversely, survival was primarily affected by CO2 rather than temperature. Survivorship at 1 dph and 16 dph was 24% and 54% higher, respectively, under elevated CO2 compared with ambient conditions. Elevated temperature increased survival (24%) at 1 dph, but not at 16 dph. These results suggest that projected climate change scenarios may have an overall positive effect on early life history growth and survival in this population of C. auratus. This could benefit recruitment success, but needs to be weighed against negative effects of elevated CO2 on metabolic rates and swimming performance observed in other studies on the same population

Elevated CO₂ and heatwave conditions affect the aerobic and swimming performance of juvenile Australasian snapper

As climate change advances, coastal marine ecosystems are predicted to experience increasingly frequent and intense heatwaves. At the same time, already variable CO₂ levels in coastal habitats will be exacerbated by ocean acidification. High temperature and elevated CO₂ levels can be stressful to marine organisms, especially during critical early life stages. Here, we used a fully cross-factored experiment to test the effects of simulated heatwave conditions (+ 4 °C) and elevated CO₂ (1000 µatm) on the aerobic physiology and swimming performance of juvenile Australasian snapper, Chrysophrys auratus, an ecologically and economically important mesopredatory fish. Both elevated temperature and elevated CO₂ increased resting metabolic rate of juvenile snapper, by 21-22% and 9-10%, respectively. By contrast, maximum metabolic rate was increased by elevated temperature (16-17%) and decreased by elevated CO₂ (14-15%). The differential effects of elevated temperature and elevated CO₂ on maximum metabolic rate resulted in aerobic scope being reduced only in the elevated CO₂ treatment. Critical swimming speed also increased with elevated temperature and decreased with elevated CO₂, matching the results for maximum metabolic rate. Periods of elevated CO₂ already occur in the coastal habitats occupied by juvenile snapper, and these events will be exacerbated by ongoing ocean acidification. Our results show that elevated CO₂ has a greater effect on metabolic rates and swimming performance than heatwave conditions for juvenile snapper, and could reduce their overall performance and potentially have negative consequences for population recruitment