Kondisi Hipoksia Dan Laju Dekomposisi Bahan Organik Di Lokasi Budidaya Ikan Waduk IR.H. Djuanda

Abstract

ABSTRAKWaduk Ir. H. Djuanda merupakan waduk multi fungsi yang salah satunya adalah untuk kegiatan budidaya ikan. Adanya input pakan dari kegiatan budidaya dapat menyebabkan peningkatan bahan organik dan penurunan konsentrasi oksigen terlarut. Kegiatan budidaya ikan dalam karamba jaring apung (KJA) menyumbang bahan organik ke perairan yang laju dekomposisinya (k) (per hari) dipengaruhi oleh suhu perairan. Tujuan penelitian ini untuk mengetahui kedalaman hipoksia di lokasi karamba jaring apung untuk budidaya ikan di Waduk Ir. H. Djuanda dan pengaruh suhu terhadap besarnya laju dekomposisi bahan organik (k). Penelitian kondisi hipoksia dilakukan di Waduk Ir. H Djuanda dan selanjutnya pengamatan BOD untuk penentuan laju dekomposisi bahan organik di Laboratorium Balai Penelitian Pemulihan dan Konservasi Sumberdaya Ikan pada bulan Februari-April 2013. Penentuan kondisi hipoksia berdasaran Peraturan Pemerintah Republik Indonesia Nomor 82 Tahun 2001 dan penentuan laju dekomposisi berdasarkan Least Square Method. Hasil penelitian menunjukkan bahwa kedalaman hipoksia dimulai pada kedalaman 3 m dan laju dekomposisi bahan organik (k) tertinggi pada suhu 28,5°C yaitu sebesar 0,189/hari. KATA KUNCI: Laju dekomposisi, hipoksia, bahan organik, suhu, Waduk Ir. H. DjuandaABSTRACT Ir H. Djuanda Reservoir is a multi-purpose reservoirs, one of which is for fisheries culture activity. Feed inputs from aquaculture activities can lead to an increase in organic matter and a decrease in dissolved oxygen concentration. Cultivation of fish in floating cage net contributing organic material into waters which the rate of organic matter decomposition (k) (per day) is affected by water temperature. The purpose of this study was to know the depth of hypoxia in floating cage net for fisheries culture in the Ir. H. Djuanda Reservoir and the effect of temperature on the amount of organic matter decomposition rates (k). Observation of hypoxic conditions was conducted in Ir. H Djuanda Reservoir and furthermore observation of BOD to determine the rate of organic matter decomposition at Research Institute for Rehabilitation and Conservation of Fish Resources laboratory in February-April, 2013. Determination of hypoxic conditions based on Government Regulation of the Republic Indonesia Number 81 Year 2001 and the determination of the rate of decomposition based on Least SquareMethod. The results showed that the depth of hypoxia began at a depth of 3 m and the higher of decomposition rate of organic matter (k) was 0.189/day at temperature 28.5°C.

Depth Profiles of Dissolved Oxygen (DO) and Hydrogen Sulfide (H2S) Concentration in a Tropical Freshwater Reservoir

“…In addition, the decomposition of organic matter such as dead plankton and the respiration process by aquatic biota can also reduce dissolved oxygen levels (Welch, 1952). The respiration process by plankton and fish causes a loss of dissolved oxygen of 5.00-15.00 mg/L and 2.00-6.00 mg/L (Astuti et al, 2014;Boyd & Lichtkoppler, 1979;Devi et al, 2017;Welch, 1952). The low dissolved oxygen is also influenced by the slow mixing speed and stagnant water in the water-sediment layer; thus, it forms a thick layer and inhibits the oxygen diffusion process in the bottom layer (Siriwardana et al, 2019).…”

“…Furthermore, Kumar (2017) stated that low dissolved oxygen levels and BOD above 5 mg/L indicate the presence of organic matter contamination. The decreased dissolved oxygen levels in water can interfere with fish survival and metabolic processes (Astuti et al, 2014). However, in July, October, and December, this phenomenon did not occur even though the BOD5 value was relatively high though the dissolved oxygen level was also high, i.e., 5.00-6.00 mg/L.…”

“…Furthermore, according to Winton et al 2019, anoxic water conditions produce H2S and NH3 gases. The deaeration process also caused a decrease in dissolved oxygen levels, inflow from groundwater, iron oxidation, and reactions by other gases such as the nitrification process (Astuti et al, 2014;Boyd & Lichtkoppler, 1979;Devi et al, 2017;Welch, 1952). According to Woldeab et al (2018), dissolved oxygen levels below 2 mg/L can cause fish death.…”

“…Kumar (2017) states that the optimal dissolved oxygen level for fish culture activities is > 4.00 mg/L. This number indicates that the waters of the Jatiluhur Reservoir have a hypoxic depth starting at 0 m. The research results of Astuti et al (2014) stated that the depth of hypoxia at the KJA location in Jatiluhur Reservoir in 2013 started at a depth of 3 m and below. This change in the depth of hypoxia occurred due to an increase in oxygen consumption by the continuous decomposition of organic matter.…”

“…Vertical distribution of temperature, pH, conductivity, ammonia, nitrite, nitrate, phosphate, and dissolved oxygen in Padaviya Reservoir, Sri Lanka (Siriwardana et al, 2019). The vertical profile of dissolved oxygen, the depth of hypoxia at the floating net cage location, and the effect of temperature on the decomposition rate of organic matter (k) in the Jatiluhur Reservoir (Astuti et al, 2014). Water quality parameters compared to quality standards following government regulation no 22 of 2021 (PP 22/2021) concerning the Implementation of Environmental Protection and Management.…”