Acid and Choking Ocean: Effects of Ocean Acidification and Hypoxia on Marine Ecosystems

Abstract

Ocean acidification is now regarded as one of the most threatening stressors on marine ecosystems. 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 hypoxia. Here I show the three case studies on the effect of ocean acidification and low oxygen on marine invertebrates: 1. Deep-sea hermit crabs, 2. Red abalone, and 3. Interaction between clams and crabs. First, low pH and low DO deteriorates the olfactory behavior of deep-sea hermit crabs (Pagurus tanneri) but increases the individual variation. It suggests that deep-sea acidification could impact hermit crabs but the population may able to adapt to future acidification. Second, 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, low pH decreased the growth rate suggesting that DO and pH separately influence the physiology of red abalone. Finally, to determine if low pH and low DO events influence the interaction between manila clams (Venerupis philippinarum) and yellow shore crabs (Hemigrapsus oregonensis), a series of experiments were conducted. Only low pH and low DO decreased burrowing behavior of manila clams and thus increaseded in relation with hypoxia. Here I show the three case studies on the effect of ocean acidification and low oxygen on marine invertebrates: 1. Deep-sea hermit crabs, 2. Red abalone, and 3. Interaction between clams and crabs. First, low pH and low DO deteriorates the olfactory behavior of deep-sea hermit crabs (Pagurus tanneri) but increases the individual variation. It suggests that deep-sea acidification could impact hermit crabs but the population may able to adapt to future acidification. Second, 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, low pH decreased the growth rate suggesting that DO and pH separately influence the physiology of red abalone. Finally, to determine if low pH and low DO events influence the interaction between manila clams (Venerupis philippinarum) and yellow shore crabs (Hemigrapsus oregonensis), a series of experiments were conducted. Only low pH and low DO decreased burrowing behavior of manila clams and thus increased