Effect of low pH on early life stages of the decapod crustacean, Dungeness crab (Cancer magister)

Dungeness crab (Cancer magister) eggs and larvae were exposed to laboratorycontrolled, low-pH seawater in an effort to assess current and predicted-future impacts of Ocean Acidification (OA) on hatching success, survival and growth. Treatment levels of pH ~8.0, ~7.5 and ~7.1 represented the wide range of pH-levels relevant to current-open-ocean, currentupwelled and future-upwelled conditions associated with C. magister habitat in the northeast Pacific Ocean. For this study, pH ~8.0 represented the “control”. C. magister eggs were exposed to treatment levels for 34 days. There was no effect of treatment on probability of hatching, however there was a delay in hatch-timing for eggs in pH 7.1. Newly hatched C. magister larvae were exposed to treatment levels for 45 days with 57.9%, 13.5%, and 21.1% surviving in pH 8.0, 7.5, and 7.1 respectively. Larvae in the low-pH treatments were 2.5-3 times less likely to survive than in the control. There was no effect of treatment on larval size at a particular larval stage, however, larvae in the low-pH treatments progressed through larval stages at a slower rate than the control. While some larvae survived the low-pH conditions to the end of the experiment, the lowest survivorship occurred in seawater reflective of pH-levels that can currently be experienced in estuaries and areas of upwelling. The results of this study indicate that low-pH seawater caused by OA can slow down progression through early life stages and that long-duration exposure can result in mortality.

Miller J. J., 2015. Effect of low pH on early life stages of the decapod crustacean, Dungeness crab (Cancer magister). MSc thesis, University of Washington, 79 pp. Thesis.


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