Seasonal development of invertebrate zooplankton on the Flemish Cap

Abstract

Flem~sh C a p was dominated by the calanoid copepod Calanus finmarchicus It const~tuted 37 to 69 % of all zooplankton sampled with coarse mesh nets (0 333 and 0 505 mm) and 15 to 33 % In fine mesh nets (0 165 mm) dunng March to August O w ~ n g to its large size, C finmarchjcus dominated the biomass of all specles sampled in both coarse and fine mesh samples The domlnant copepod species in flne mesh samples (0 165 mm) were Oithona s~mllis and 0 atlanOca which together compnsed 20 to 4 2 O/a of all specles sampled C finmarcl~icus formed a d~screte populahon on Flemish C a p with peak spawning in mid-Aprll beginning first in waters 5 200 m depth Peak biomass occurred In late May and probably early June coincident w ~ t h peak abundance of late-stage copepodites Significant differences were observed in the rate of C finmarchicus developinent and absolute abundance among years sampled on Flemish Cap Differences in development were related to differences in the seasonal h e a t ~ n g of surface waters on Flemish Cap in different years It is hypothes~zed that these differences in rate of development and absolute abundance of C finmarchlcus and other copepods w ~ l l have a significant effect on larval fish feedlng, growth and survival