Biomass, carbon ingestion, and ammonia excretion by zooplankton associated with an upwelling plume in western Cook Strait, New Zealand

Abstract

Abstract The biomass, elemental composition, and rates of ingestion and excretion by macrozoo‐plankon associated with the upwelling plume off the north‐west coast of the South Island, New Zealand, were investigated in March‐April 1983. Ingestion and excretion rates of the major zoo‐plankton species were combined with abundance data to determine the spatial and temporal variability which may influence phytoplankton dynamics in the plume system. Zooplankton biomass near Cape Kahurangi was dominated by small copepods like Acartia ensifera (up to 60%). In the South Tar‐anaki Bight, larval and adult forms of the euphau‐siid Nyctiphanes australis commonly contributed up to 60% of biomass. However, the carbon ingestion and ammonia excretion patterns of N. australis were spatially displaced from those of the total zooplankton community in the South Taranaki Bight because of higher weight‐specific metabolic rates for the smaller copepods. Close to the focus of the upwelling near the Kahurangi Shoals, grazing press...