PLANKTON COMMUNITY STRUCTURE AND FISH’S EATING-HABITS CHANGE IN RAWA BANGKAU, SOUTH KALIMANTAN

Abstract

The waters of Rawa Bangkau monotonous swamp, including the South Hulu Sungai Regency, potentially have several types of swamp fish that are economically valuable, quite high-priced, and popular with the South Kalimantan people. To date, there has been limited data about the lake and the resources it holds; the data is essential for proper management, among which are about the organisms making up the lake. Accordingly, the objectives of this study were (1) to obtain data and study the conditions of water quality and biology of Rawa Bangkau by examining the structure of the plankton community, (2) to clarify the stomach contents of Swamp fish, and (3) to analyze changes in Swamp fish food through a preference index (choice) based on Ivlev, 1961. The researchers carried out sampling in July-August 2020. The measurement results showed that: (1) DO (Dissolved Oxygen) measurements showed that the water conditions were not suitable for aquatic biota and lightly polluted. The nitrate content was in mesotrophic to oligotrophic conditions. The study site's abundant and diverse plankton showed low to moderate values, which was the same case with the uniformity and dominance index; (2) Fish guts indicated that the fish food was relatively the same as what was available in the waters (plankton); (3) The fish’s eating habits changed due to natural food unavailability. The preference index showed that fish did not choose their food type – they ate the