SEASONAL STUDY OF GRAZING BY METAZOAN ZOOPLANKTON IN THE MESOHALINE CHESAPEAKE BAY

Grazing of phytoplankton by the metazoan zooplankton community was measured on 5 dates from March to August 1987, and 4 dates from March to October 1988 at a single Station in the mesohaline Chesapeake Bay, USA. In situ grazing measurements were made on several taxa including copepod nauplii and meroplanktonic larvae. Zooplankton grazing was dominated by Acartia species copepods in March and August, polychaete larvae in May, and the cyclopoid copepod Oithona colcarva in June 1987 and October 1988. Copepod nauplii were nearly always important grazers because of their relatively high biomass and weight-specific ingestion rates. The amount of daily phytoplankton production removed by zooplankton in 1988 varied between 12 and 103 %, with March > August > October > May.