Abundance and Distribution of Zooplankton on Georges Bank During 1995 and 1996

Ted Durbin, Peter Garrahan, and Maria Casas

Depth-stratified zooplankton samples were collected from Georges Bank with a plankton pump and a 1 m² MOCNESS during 1995 and 1996 as a part of the U.S. GLOBEC Georges Bank program. All developmental stages of Calanus finmarchicus and Pseudocalanus spp. were enumerated while other copepods were grouped as nauplii, copepodites or adults. During both years recruitment of Calanus began in late December/early January in the southern Gulf of Maine with the new generation being advected onto Georges Bank in the region of the Northeast Peak. This winter generation spread along the Southern Flank reaching maturity in late April and May. A large second generation was produced in June. Calanus did not appear in the central well-mixed region of the Bank until March and then disappeared again in May. Pseudocalanus showed a similar seasonal pattern but remained in the central region of the Bank until the end of the sampling period. Other dominant copepods included Centropages typicus, C. hamatus, Oithona similis, and Temora longicornis. Planktonic hydroids were greatest in abundance on the crest during May and June.