Abundance and distribution of Calanus finmarchicus on the Georges Bank during 1995 and 1996

Document Type

Conference Proceeding

Date of Original Version



Depth-stratified zooplankton samples were collected from the Georges Bank with a plankton pump and a 1 m2 MOCNESS during 1995 and 1996 as part of the US GLOBEC Georges Bank program. All development stages of Calanus finmarchicus were enumerated. During both years, recruitment of C finmarchicus began in late December/early January in the southern Gulf of Maine, with the G1 generation being advected onto the northern edge of the Georges Bank. This winter generation spread across the bank, reaching the S Flank by March. It immediately began to mature, replacing adults of the G0 generation. Because of the prolonged period that the G0 population was present, there was a considerable overlap of G1 and subsequent generations. Nauplii were at a minimum during May throughout the region during both years. A large increase in numbers of nauplii was observed on the NE Peak and the S Flank of the Georges Bank during June 1995, but only on the S Flank during June 1996. The decline in abundance of nauplii in this region during May might have been due to food limitation of reproduction. On the Crest, numbers of C. finmarchicus declined following the March-April peak, reaching very low levels during June of both years. This appears to be in response to high levels of predation and isolation of the waters of the Crest as the tidal-mixing front strengthens. The development of the G1 generation on the Georges Bank was earlier in 1995 than during 1996, but the peak abundance was greater during 1996. Mean temperatures on the Georges Bank were about 1°C colder during winter 1996, and the delay in development and larger numbers of peaks that year are consistent with the effects of the colder temperatures on development. © 2000 International Council for the Exploration of the Sea.

Publication Title, e.g., Journal

ICES Journal of Marine Science