Temporal variability and production of Euterpina acutifrons (Copepoda: Harpacticoida) in the cananeia lagoon estuarine system, Sao Paulo, Brazil

Diel and seasonal variations in abundance, population structure, biomass and production rate of the harpacticoid copepod Euterpina acutifrons were studied in the Cananeia Lagoon estuarine system, Sao Paulo, Brazil. Zooplankton samples were collected at 4-h intervals during multiple 24-h periods, from February 1995 to January 1996. Copepodites and adults of E. acutifrons were present in the plankton throughout the year (temperature, 18.6-29.4 degreesC; salinity, 4.5-33.0 psu; chlorophyll-a concentration, 1.32-20.42 mug l(-1)). Abundance of E. acutifrons showed considerable diel variations. On most sampling dates, higher abundances were recorded at times when salinity was higher. Biomass varied from 0.044 +/- 0.046 (daily mean +/- SD) to 5.264 +/-3.425 mg C m(-)3. The estimated production rates (minimum +/- SD-maximum +/- SD) were 0.034 +/-0.035-4.95 +/-3.25 (Ikeda-Motoda model), 0.035 +/-0.036-5.123 +/-3.347 (Huntley-Lopez model), and 0.016 +/-0.017-2.101 +/-1.372 mg C m(-3) d(-1) (Hirst-Sheader model).