Vertical distribution and seasonal abundance of microzooplankton and its relationship with some environmental variables in Turpialito, Gulf of Cariaco, Venezuela

The vertical distribution of microzooplankton and its relationship to certain environmental variables was carried out in a locality on the Gulf of Cariaco (Turpialito). Monthly samples were collected with a Niskin bottle (5 L) to measure temperature, chlorophyll a, oxygen, salinity, seston., on the surface, and at 0, 8, 21 and 34 meter depths during the period October 1992-December 1993. Samples fof microzooplankton were collected filtering seawater through a 20-mum sieve. Samples were preserved with neutralized formaldehyde (5%). The maximum concentrations of microzooplankton were located from 5 to 15 m, the highest value (32x10(4) org/ m 3) was measured in December 1993, while the smallest values (< 2x10(4) org/m(3)) were observed between December 1992 and February 1993. Nuclei of high phytoplankton biomass (5mug/L) were observed between 4 and 16 m. Multiple regression analysis indicated the phytoplankton biomass, measured as concentration of chlorophyll a, was the factor that explained the highest variability (34%) of microzooplankton abundance, followed by surface temperature (21%). We discuss the repercussions of the variability of these factors with regard to the patterns of zooplanktonic production in the area.