Effect of seawater warming and low dissolved oxygen on behavior and physiology of marine benthic invertebrates

Abstract

Increased carbon dioxide emission increase temperature of not only atmosphere and but also seawater. Because of low dissolution of oxygen and increased biological activity, ocean warming entails deoxygenation or hypoxic problems in the seawater. We explored the combined effect of seawater warming and low dissolved oxygen (DO) on behavior and physiology of marine invertebrates such as Manila clams, Pacific abalone, and sea urchins. Under high temperature (23.5°C) and low DO (3mg/L) treatment, young Manila clams (Venerupis philippinarum) increased their emerging behavior and eventually had the highest mortality among different treatments. Interestingly, mortality under high temperature and high DO was higher than that under control temperature (20°C) and low DO. There was no significant difference in their oxygen consumption rates between treatments. In Pacific abalone (Haliotis discus hannai), increased temperature (23°C) had a positive effect on foraging behavior but decreased oxygen had a negative effect. On the other hand, in adult sea urchins (Mesocentrotus nudus), there was no significant effect of temperature (22.5°C vs 18.5°C) and DO (6-7mg/L vs. 3.5 mg/L) on foraging and righting behavior. Given all these results, temperature and DO have differential effects on invertebrates and tolerance to these stressors are different depending on species.ater. We explored the combined effect of seawater warming and low dissolved oxygen (DO) on behavior and physiology of marine invertebrates such as Manila clams, Pacific abalone, and sea urchins. Under high temperature (23.5°C) and low DO (3mg/L) treatment, young Manila clams (Venerupis philippinarum) increased their emerging behavior and eventually had the highest mortality among different treatments. Interestingly, mortality under high temperature and high DO was higher than that under control temperature (20°C) and low DO. There was no significant difference in their oxygen consumption rates between treatments. In Pacific abalone (Haliotis discus hannai), increased temperature (23°C) had a positive effect on foraging behavior but decreased oxygen had a negative effect. On the other hand, in adult sea urchins (Mesocentrotus nudus), there was no significant effect of temperature (22.5°C vs 18.5°C) and DO (6-7mg/L vs. 3.5 mg/L) on foraging and righting behavior. Given all these results, temperature and DO have differential effects on invertebrates and tolerance to these stressors are different depending on species.