Comparison of phytoplankton macromolecular compositions and zooplankton proximate compositions in the northern Chukchi Sea

Abstract

The macromolecular(proteins,lipids,andcarbohydrates)compositionofphytoplanktonandtheproxi- mate (water,proteins,lipids,andash)andelemental(carbonandnitrogen)compositionsofmesozoo- plankton weredeterminedinthenorthernChukchiSeatoestablishtherelationshipbetween zooplankton andtheirphytoplanktonfoodsource.Amongthephytoplanktonmacromoleculesexamined in thisstudy,lipidshadthehighestcontents(58.478.2%) andproteinshadthelowest(16.177.3%), which maybeaconsequenceofanitrogendeficiency inphytoplanktongrowthduringthestudyperiod. In contrast,proteins(59.7710.6%DW)werethemajorproximatecomponentsinthemesozooplankton community,whichwasdominatedbycopepodsupto71%oftotalabundance.Thelowlipidcontents (13.8712.4%DW)inthemesozooplanktoncommunityinthisstudymightbeduetothedominanceof small speciessuchas Calanus glacialis, whichgenerallyhaverelativelylowerlipidcontentsthanlarge copepods. Moreover,thespawningperiodof C. glacialis from ApriltoJunemightbeanadditionalreason for thelowlipidcontents,becausecopepodshavenormallyverylowlipidcontentsafterspawning.The low lipidcontentsresultedinalowenergycontentinthismesozooplanktoncommunityinthenorthern Chukchi Sea.Thedifferentbiochemicalcompositionsofphytoplanktonandzooplanktonshouldbe considered inordertounderstandtheimpactsofclimatechangeonthequalityofpreyprovidedby lowertrophiclevelsandsubsequentlyonArcticmarineecosystems.