The effects of simulated ocean acidification on the behaviour and physiology of the economically important Dungeness crab, Metacarcinus magister

Abstract

Although there is much controversy regarding the effects of ocean acidification on the behaviour of marine fish, marine invertebrates have been much less studied. Dungeness crabs, Metacarcinus magister, are found on the West coast of North American and their commercial and recreational fishery is one of the most valuable fishery in the Pacific region, with annual revenues of $220 million. Dungeness crabs live in the deep-sea and enter intertidal areas in order to find food. Previous studies have found that they routinely encounter pCO2 concentrations of up to 1300 µatm in their coastal habitat and that these levels of ocean acidification can affect larval development and mechanoreceptors. We exposed adult Dungeness crabs to control (600 µatm) and high pCO2 (1300 µatm) for 10 days and assessed their behaviour and physiology using electrophysiology, gene expression, immunohistochemistry and transmission electron microscopy of their olfactory organs, the antennules. Dungeness crabs exposed to high pCO2 had a 25% lower rate of antennular flicking rate in response to all concentrations of cadaverine, a food cue, than crabs exposed to control pCO2. No differences in antennular flicking were found in response to ammonium chloride, a deterant, however there was a large increase in the expression of Rh proteins that function as ammonia transporters in their antennules indicating a potential compensatory mechanism. We propose that a more holistic approach to the overall question of the effects of ocean acidification needs to be taken at multiple levels of biological organization and using environmentally relevant odorants and concentrations.