Variability in zooplankton distribution at cyclone Enakai in the lee of the Hawaiian Islands

Abstract

Enakai, a cyclonic eddy, formed in the lee of the Hawaiian Islands and was observed in NAVOCEANO satellite imagery during the week of 30 Oct. 2010. This study examines the physical, chemical and biological processes taking place within Enakai, and attempts to place them within the framework of eddy life histories. Cyclonic eddies are known to distort density surfaces in the ocean, causing deep water nutrients to upwell into the euphotic zone where they can be utilized by phytoplankton. Enhanced primary productivity provides food sources for zooplankton, initiating a cascade of ecosystem productivity. Plankton net tows showed that zooplankton abundances within Enakai were elevated by a factor of 150%-250% relative to surrounding waters at the time of the survey.