Abstract
This dissertation focuses on the distribution, reproduction, and transport of zooplankton in the Chukchi and Beaufort seas and adjacent Canada Basin. Specifically, it analyzes 1) the species-specific distribution of copepod nauplii as it is forced by the surface layer mesoscale circulation and physical properties, 2) the reproduction of the dominant copepod Calanus glacialis in the western Arctic, and 3) the effects of eddy transport on the zooplankton community in the Chukchi and Beaufort seas and Canada Basin. To achieve this I adapted a molecular identification method to work with small crustaceans. The method was successfully used to generate a sequence database from adult copepods of species present in the region. Differences in the D1/D2 domains of the large subunit ribosomal were sufficient for the identification of all species present in the western Arctic with the exception of two sibling Calanus copepods which were discriminated using the mitochondrial cytochrome oxidase I gene. The application of this semi-robotic protocol to selected surface samples collected from the USCGC Healy in summer 2004 revealed that four copepod species dominated the naupliar community: Oithona similis, C. glacialis, Pseudocalanus minutus, and P. mimus. Each species had different abundance and distribution patterns related to their specific life cycles and environmental affinities. The molecular identification method was then applied to study the egg production rates of C. glacialis and differentiate it from C. marshallae. This work validated reported spatial and seasonal variations in egg production rates in C. glacialis and showed that an increase in primary production in summer 2004 compared to summer 2002 did not result in an increase in secondary production of this copepod. The last component of this study is the result of a unique sampling design to study shelf-basin interactions. The results provided evidence of on-shelf transport of basin organisms by a wind-induced upwelling event and of eddy-mediated advection of zooplankton from the surrounding shelves into the Arctic basin. Overall, this study integrated new molecular tools and unusual sampling opportunities to advance our understanding of the role zooplankton in this Arctic ecosystem.