SUMMARY
Situ Gintung merupakan salah satu perairan yang diaplikasikan program zero karamba jaring apung (KJA) berdasarkan Peraturan Presiden Nomor 15 Tahun 2018 Tentang Percepatan Pengendalian Pencemaran dan Kerusakan Daerah Aliran Sungai Citarum dengan tujuan dapat memperbaiki kualitas dan nutrien perairan. Tujuan penelitian ini mengevaluasi program zero KJA terhadap kualitas dan status nutrien berdasarkan indeks biotik yaitu plankton dan gastropoda. Pengambilan sampel pada lima stasiun di Situ Gintung setelah diaplikasikannnya program zero KJA. Faktor kimia-fisik yang diukur adalah suhu air, derajat keasaman (pH) air, kecerahan, padatan terlarut total, kekeruhan, dan oksigen terlarut (DO) dengan water quality checker (WQC). Pengujian nitrit dan fosfat dilakukan dengan menggunakan UV-Vis Spektrofotometer. Pengambilan sampel plankton menggunakan metode filtrasi dan gastropoda dengan cara hand collecting pada kuadrat 1 m2. Hasil pengukuran kimia-fisika pada setiap periode secara keseluruhan Situ Gintung masih berada di dalam baku mutu PP. No. 22 Tahun 2021 dengan nilai water quality index (WQI) yang terus mengalami penurunan dari Januari hingga Maret (81,42 menjadi 67,14). Kepadatan fitoplankton mengalami penurunan dari Januari hingga Maret dan kepadatan zooplankton cenderung stabil. Komposisi sebaran fitoplankton secara umum didominasi oleh kelompok Cyanobacteria, Bacillariophyceae, dan Chlorophyceae. Komposisi sebaran zooplankton didominasi oleh Brachionus sp., Daphnia sp., dan Nauplius sp. Nilai keanekaragaman (H’) untuk plankton dan gastropoda berada dalam kategori sedang (1<H’<3), untuk nilai kemerataan (e) berada dalam kategori kemerataan tinggi (E>0,5), dan nilai dominansi (C) yang menunjukkan tidak adanya dominansi (C<0,5). Nilai indeks saprobik dan indeks diatom menunjukan Situ Gintung dalam keadaan tercemar sedang dengan status nutrien mesotrofik-eutrofik.Situ Gintung is one of the reservoirs in which a zero floating net cages (FNC) program has been applied according to the Presidential Regulation Number 15 of 2018 concerning the Acceleration of Pollution Control and Damage to the Citarum River Basin with a purpose to improve the quality and nutrients of the river. The purpose of this study was to evaluate the water quality and nutrient status in Gintung Reservoir based on biotic index post implementation of the zero FNC program in the reservoir. Sampling activities were carried out in five stations within Gintung Reservoir post implementation of the zero FNC program. In-situ chemical-physical factors measured were water temperature, degree of acidity (pH) of water, brightness, total dissolved solids (TDS), turbidity (turbidity), and oxygen content (DO) using water quality checker equipment. Nitrite and phosphate testing were done ex-situ using a UV-Vis Spectrophotometer. Plankton samples were collected using filtration method. Gastropod samples were collected by hand using a quadran of 1 m2. Results of the chemical-physical measurements showed that water quality of Gintung Reservoir is still within the quality standard of PP No. 22 of 2021 with the water quality index (WQI) continued to decline from January to March (81.42 to 67.14). Phytoplankton density decreased from January to March while zooplankton density was relatively stable. The composition of phytoplankton distribution was dominated by groups of Cyanobacteria, Bacillariophyceae, and Chlorophyceae. The composition of the zooplankton distribution was dominated by Brachionus sp., Daphnia sp., and Nauplius sp. The diversity values (H’) for plankton and gastropods were in the medium category (1<H’<3), the evenness values (e) was in the high category (E>0.5) and the dominance value (C) showed no dominance (C<0.5). Saprobic and diatom indexes showed that Gintung Reservoir was categorized as mesotrophic-eutrophic waterbody with moderately polluted condition.