Instrumentation for the Analysis of Zooplankton Lipids

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This proposal seeks support for an analytical instrument designed to separate and quantify lipid classes. The instrument, known commercially as an Iatroscan, combines two principles: thin-layer chromatography (TLC) with flame ionization detection (FID). The advent of the Iatroscan, less than a decade ago, made possible sensitive, rapid quantitation of lipid classes from planktonic organisms, seston, and sediments. Lipid class composition from as little as a single copepod can be analyzed, now permitting lipids to be used as a tool in the study of population biology. Purchase of an Iatroscan will permit one study to be completed and a preliminary exploration conducted as a foundation for future research. First, the effects of an oceanic front on copepod nutrition will be evaluated. The hypothesis will be tested that interspecific differences exist in nutritional responses of 3 suspension-feeding copepods to the Ensenada front, a persistent, deep-water frontal system in the California Current. The species of interest are Eucalanus californicus, Metridia pacifica, and Calanus pacificus californicus. Storage lipids (wax esters, triacylglycerols) and gut fluorescence will be used as "condition factors," to assess the nutritional status of these 3 species on a series of lines that intersect the frontal region. Secondly, the possibility that vertically subdivided copepod populations can be differentiated by lipid profiles will be explored. The latter issue bears on the problem of the continuous/discontinuous character of zooplankton population growth as well as the vertical transport of lipids by migratory zooplankton. Both the effects of the Ensenda front on zooplankton nutrition and the vertical lipid variation study will be done with existing zooplankton samples that were collected for this purpose and frozen during cruises in 1988 (ZBI and Fronts '88).