SEBARAN SPASIAL PLANKTON DI PERAIRAN BAWEAN

The presence of phytoplankton in the water is very important because it serves as a primary producer that is often used as an indicator of aquatic fertility. The objective of the research was to determine the species, density and spatial distribution of plankton in the Bawean waters, Gresik regency. Baruna Jaya VIII research vessel was used for sampling on 29-30 April 2009. Sampling locations were set up in two stations on the position of 06°05'S, 112°36'E and 06°05'S, 120°12'E, and water samples were taken at depths of 0m, 20m, 40m and 60m in each station. Water was collected using water samplers at amounts of 10 liters each depth, thenwas filtered using plankton net, and then preserved with formalin 4%. Identification of genus plankton was carried out in the laboratory.The results showed that there were 20 genus of phytoplankton and 38 genus of zooplankton which were spread outin each depth of the water column unevenly. Plankton density was as much as 2330 cells / liter, while the density of zooplankton was as much as 507 individuals / liter. The highest density of phytoplankton was found in the water column depth of 20 m, while the lowest was found at the depth of 60m. The highest density of zooplankton was found in the surface, then decreases as the depth of waters. The dominant genusof phytoplankton were Pleurosigma sp., then Rizosolenia sp., Skeletonema sp., and the least was Actinocyclus sp. The dominant species of zooplankton are Ceratium sp. then Tintinopaial sp., and nauplius sp