Metabolic Enzyme Activities of Benthic Zoarcids off the Coast of California

Abstract

Our knowledge of deep-sea ecosystems is poor. Specifically, knowledge is lacking concerning deep-sea benthic communities and their metabolic rates. There has been much debate concerning what controls metabolic rates in animals, whether it is size and temperature or declining light levels and the selective pressure for locomotory capacity. Zoarcids are widely distributed and speciose, therefore, a great model for this research. The rates of four enzymes in twelve species of zoarcids were examined as a biochemical proxy for metabolic activity. Enzyme assays were performed on two anaerobic enzymes, citrate synthase and malate dehydrogenase, and two aerobic enzymes, pyruvate kinase and lactate dehydrogenase. Both benthic and benthopelagic species were analyzed, over a broad depth range and size gradient. No significant decline in enzymatic activities with increasing median depth of occurrence for both benthic and benthopelagic zoarcids was found. Only one benthic species, Lyconema barbatum exhibited changes in aerobic enzymatic activity with increasing mass, however only between the shallower specimens. The results from this research show that variations in enzyme activities exist among the different species of benthic and benthopelagic zoarcids, but is not accounted for by depth of occurrence or size. It is likely that the differences between species in enzymatic rates reflect the feeding and swimming lifestyles of these fishes. Further study is needed to understand the factors affecting the variation in enzyme activity.