Impact of exposure to elevated pCO 2 on the physiology and Behaviour of an important ecosystem engineer, the burrowing shrimp Upogebia deltaura

Abstract

There is an increasing need to predict the effects of global climate change on ecologically important marine organisms and a demand for proactive solutions to reduce CO 2 emissions. CO 2 sequestration is one such method. While this offers a practical solution, recognition should be given to the potential for considerable localised effects on marine organisms in the event of leakage. This laboratory study quantifies the impact of exposure to elevated pCO 2 conditions on the physiological and behavioural responses of a relatively tolerant marine organism. Burrowing shrimps Upogebia deltaura were exposed to CO 2-enriched seawater for 35 d to treatments of 1396 μatm (pH 7.64), 2707 μatm (pH 7.35) and 14 110 μatm (pH 6.71). CO 2 levels represented scenarios which included coastal ocean acidification and extremely elevated CO 2 associated with geological CO 2 sequestration leaks. Results were compared with those from shrimps maintained in a control treatment (pH 7.99). U. deltaura appeared to be tolerant to elevated pCO 2 predicted to occur in the year 2100 (1396 μatm, pH 7.64). However, at 2707 μatm (pH 7.35) shrimps experienced extracellular acidosis, but no difference in haemolymph bicarbonate concentration, suggesting they have little or no buffering capacity, although there was no evidence of other physiological costs in terms of metabolism, osmotic regulation, shell mineralogy, growth and overall activity. At pH 6.71, before 100% mortality occurred, significant differences in activity were observed compared with shrimps in other pH treatments. Results suggest deleterious consequences for benthic ecosystems in the event of a CO 2 sequestration leakage. © Inter-Research 2012.