Graduation Year


Document Type




Degree Granting Department

Marine Science

Major Professor

Joseph J. Torres, Ph.D.

Committee Member

Edward S. Vanvleet, Ph.D.

Committee Member

Stephen P. Geiger, Ph.D.


enzyme, analysis, Euphasia, calanoides, Metridia, Paraeuchaeta, globec, diapause


We compared four metabolic indicators of nutritional state: citrate synthase activity (CS), malate dehydrogenase activity (MDH), lactate dehydrogenase activity (LDH) and percent body protein to each other and to respiration measurements. These comparisons were made for four species of copepods (Calanoides acutus, Metridia gerlachei, Paraeuchaeta antarctica and another form of Paraeuchaeta that was unidentifiable to species due to its early life stage), three species of Euphausids (Euphausia crystallorophias, Euphausia triacantha, Euphausia superba (including both F6-furcilial and adult stages)) and Thysonessa macrura which were collected off the Western Antarctic Peninsula (WAP) during Spring/Summer and Fall/Winter. Most species showed significant changes in one or more of the enzyme activities. In general, species that engage diapause during the Winter months showed a decrease in citrate synthase whereas those that actively feed throughout the year showed no significant changes. There was also evidence of correlations between citrate synthase activity and respiration as well as between malate dehydrogenase activity and respiration. The observed patterns are consistent with existing models of survival strategy for these Antarctic species.