DYNAMICS OF CALANOIDES-ACUTUS (COPEPODA, CALANOIDA) IN ANTARCTIC COASTAL WATERS

Observations of the population dynamics, distribution, abundance, feeding activity and egg production of Calanoides acutus were made in the period from mid-December 1986 to late March 1987. Spawning is presumed to have begun as early as October, since the population reached the copepodite I stage of development by early December. Egg production, which was not related to ambient chlorophyll concentrations in the range 4.4-18.5-mu-g l-1, ceased by mid-January. Feeding intensity of adult females, indicated by gut pigment content, was correlated with surface chlorophyll concentration. No evidence was found for diel periodicity in feeding. Younger copepodite stages (CI-CIII) were concentrated in the 0-100 m depth stratum, whereas later stage copepodites tended to be equally distributed throughout the upper 200 m. No evidence was found for diel vertical migration. All copepodite stages in the Gerlache Strait tended to be concentrated in the upper 100 m. Abundance of C. acutus was consistently greater in Gerlache Strait waters than elsewhere in the study area. The population attained overwintering copepodite stages CIV and CV by March. Downward ontogenetic migration of the overwintering stages occurred in the Drake Passage by late March, but was delayed in the relatively food-rich waters of the Gerlache Strait.