Effects of ocean acifidification and hypoxia on behavior and species interaction of fisheries species

Abstract

Ocean acidification is now regarded as one of the most threatening stressors on marine aquaculture species. Because high CO2 event in the seawater is often accompanied by lowly dissolved oxygen (DO), the effect of ocean acidification should be studied in relation with low oxygen. Here I show the two case studies on the effect of ocean acidification and low oxygen on two aquaculture species: red abalone and manila clams. First, to explore the possibility that coastal upwelling characterized by low pH and low DO influences the growth and mortality of red abalone (Haliotis rufescens), the population was intermittently exposed to low pH and low DO conditions. While low DO increased the mortality of abalone (Fig. 1), low pH decreased the growth rate suggesting that DO and pH separately influence the physiology of red abalone. Second, to determine if low pH and low DO events influence the behavior and physiology of manila clams (Venerupis philippinarum), a series of experiments were conducted. Although manila clams are highly tolerable to low pH only or low DO only conditions, low pH combined with low DO conditions decreased burrowing behavior of manila clams (Fig. 2) and thus increasedthe consumption rate of yellow shore crabs (Hemigrapsus oregonensis), suggesting that there is a synergistic effect between CO2 and oxygen. Given all results, aquaculture resources could be differently influenced by ocean acidification. be studied in relation with low oxygen. Here I show the two case studies on the effect of ocean acidification and low oxygen on two aquaculture species: red abalone and manila clams. First, to explore the possibility that coastal upwelling characterized by low pH and low DO influences the growth and mortality of red abalone (Haliotis rufescens), the population was intermittently exposed to low pH and low DO conditions. While low DO increased the mortality of abalone (Fig. 1), low pH decreased the growth rate suggesting that DO and pH separately influence the physiology of red abalone. Second, to determine if low pH and low DO events influence the behavior and physiology of manila clams (Venerupis philippinarum), a series of experiments were conducted. Although manila clams are highly tolerable to low pH only or low DO only conditions, low pH combined with low DO conditions decreased burrowing behavior of manila clams (Fig. 2) and thus increasedthe consumption rate of yellow shore crabs (Hemigrapsus oregonensis), suggesting that there is a synergistic effect between CO2 and oxygen. Given all results, aquaculture resources could be differently influenced by ocean acidification.