Daily zooplankton grazing rates off the coast of baja california

During the summer of 1990, a 15-day (14 to 28 July) time series was generated to measure the daily grazing rates of macrozooplankton (>200 Pm), studying the changes in the chlorophyll a concentration at a station on the coast of Baja California, Mexico. The water column showed stable hydrographic conditions. Copepods and euphasiids were the most abundant organisms within the macrozooplankton populations. In general, grazing (0 to 2.5 d-‘) and filtration (0 to 8.8 ml erg-’ d-‘) rates were of the same order of magnitude as values previously reported. Overall phytoplankton consumption by the macrozooplankton was about 25%. Grazing and tiltration rates showed great variability from day to day (>lOO%). It would, therefore, be advisable to generate time series studies of at least 7 to 10 days, in order to arrive at a better understanding of the zooplankton pressure on the phytoplankton populations.