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 an d production rate of the harpacticoid copepod Euterpina acutifrons were stu died in the Cananeia Lagoon estuarine system, Sao Paulo, Brazil. Zooplankto n samples were collected at 4-h intervals during multiple 24-h periods, fro m February 1995 to January 1996. Copepodites and adults of E. acutifrons we re present in the plankton throughout the year (temperature, 18.6-29.4 degr eesC; 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 m ost sampling dates, higher abundances were recorded at times when salinity was higher. Biomass varied from 0.044 +/- 0.046 (daily mean +/- SD) to 5.26 4 +/-3.425 mg C m(-)3. The estimated production rates (minimum +/- SD-maxim um +/- 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 +/-1.3 72 mg C m(-3) d(-1) (Hirst-Sheader model).