Hopkins Marine Station Student Paper

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Title: Physiological and biochemical differences correlated with vertical distribution in the mussel Mytilus californianus
Student Author(s): Harden, Wesley
Faculty Advisor(s): Somero, George
Location: Final Papers Biology 175H
Date: 2001 2001
Abstract: In this study I examined metabolic rates of Mytilus californianus located at the upper and lower extremes of the Mytilus distribution zone in an exposed rocky intertidal area at Hopkins Marine Station in Pacific Grove, CA. Mussels high in the zone spend less time exposed to normoxic conditions as a result of longer emersion periods. They also experience greater temperature fluctuations. Such abiotic stresses were expected to make metabolic rates among high and low mussels different. Respiration (O2 consumption) and malate dehydrogenase activities of gill tissue were used as indicators of metabolism. The design of this experiment led to mussel acclimation over a period of 25 days. When plotted against time, enzyme activities of low mussels showed a significant (p = 0.048) decrease in activity. Additionally, a significant (p = 0.014) decrease was observed in O2 consumption of high mussels. The unexpectedly rapid physiological plasticity shown by M. californianus resulted in small sample sizes (enzyme n = 10, respiration n = 4) of freshly collected individuals, which may have contributed to the non-significant differences seen in high and low mussel MDH activities (p = 0.059) and respiration rates (p = 0.74). It was also concluded from this experiment that MDH activity is not a good predictor of respiration rate, possibly due to its role in both aerobic and anaerobic metabolism.