Distribution and egg production of Pseudocalanus species in the Chukchi Sea

The distribution and egg production of Pseudocalanus species was studied in the Chukchi Sea during August 2004. Three species were identified throughout the study area, Pseudocalanus minutus, Pseudocalanus acuspes and Pseudocalanus newmani. The more subpolar/temperate P. newmani-dominated stations where water was warmer and likely influenced by Alaska coastal waters, and it penetrated northward into the south-eastern corner of Herald Valley. The Arctic P. acuspes dominated the colder waters. The number of eggs produced by individuals and populations differed among species, primarily because of differences in body size, but mass-specific egg production was similar among species, and was on the order of 15% per day. Future increases in the prevalence of P. newmani within the Chukchi Sea might be anticipated, and would result in a decreased average size of the copepod community, with potential implication for higher trophic levels.