The structure community of zooplankton and environmental conditions of the Kalimireng River estuary, Gresik, East Java
Abstract Water quality monitoring is a key component in the management of these important water resources and ecosystems. Biological indicators can be monitored continuously and are easy instructions for monitoring the occurrence of pollution. One of the biological parameters that can be used as a marker of environmental conditions is plankton. zooplankton can be used as study material to determine the quality and water productivity. The method used in this research is descriptive to determine the water quality condition in the estuary of the Kalimireng river biologically through the identification and characterization of zooplankton. Observations of plankton identification, plankton abundance, dominance index, and characterization of zooplankton were analyzed by fluorescence microscope observation. Three species of zooplankton were found in the waters of the Kalimireng estuary, Leptodiaptomus sp., Canthocamptus staphylinus, and Diaphanosoma bracyurum. Zooplankton is more abundant in water conditions at high tide compared to water conditions at low tide. At high tide, the highest abundance value was obtained at the station I at week 3, 843 ind/mL. At low tide, the highest abundance value was obtained at the station I at week 2,251 ind/L. The highest Dominance Index (D) at tidal water conditions is shown at station 2. This indicates that there is a community that dominates at that station.