Daily egg production rate of the planktonic calanoid copepod Acartia lilljeborgi Giesbrecht in the Cananeia Lagoon estuarine system, Sao Paulo, Brazil

Seasonal variation in daily egg production rate of the planktonic calanoid copepod Acartia lilljeborgi Giesbrecht in relation to temperature, salinity and chlorophyll a concentration was studied in the Cananeia Lagoon estuari ne system, from March 1995 to January 1996. Recently captured A. lilljeborg i adult females were individually incubated in bottles filled with surface water screened through a 40-mum mesh, containing a natural assemblage of ph ytoplankton in the laboratory, at temperatures corresponding to ambient. Da ily egg production rate ranged from 13.8 +/-3.5 to 66.8 +/- 15.1 eggs femal e(-1) d(-1) (mean +/- 95% CL). The mean and maximum rates of daily egg prod uction increased with temperature from 19.5 to 25.2 degreesC but then decre ased with further increase in temperature at 28.4 through 29.1 degreesC, at taining the highest rates at approximately annual mean ambient water temper ature (ca. 24-25 degreesC). The egg production rates increased linearly wit h chlorophyll a < 40 mum fraction. Hatching success varied from 68.6 to 91. 9%. Cannibalism varied from 1.4 +/-0.7 to 7.1 +/-3.3 nauplii female(-1) d(- 1) (mean +/- 95% CL). These results suggest that water temperature and phyt oplankton concentration are important factors affecting the egg production rate of A. lilljeborgi in the Cananeia Lagoon estuarine.