Evaluasi kualitas air dan respons fisiologis udang vaname dalam media budidaya mengandung Oscillatoria sp.

Abstract

Permintaan udang vaname yang tinggi menyebabkan adanya peningkatan produksi udang vaname hampir di seluruh belahan dunia termasuk di Indonesia. Peningkatan padat tebar dilakukan untuk memperoleh hasil produksi yang lebih tinggi, sistem intensif hingga supra intensif banyak dipilih untuk budidaya udang saat ini. Sistem intensif mengandalkan pakan buatan untuk pertumbuhan udang selama proses budidaya berlangsung. Hal tersebut ternyata memberikan dampak berupa adanya penumpukan limbah sisa pakan didasar tambak. Limbah sisa pakan didasar tambak menyebabkan terjadinya dinamika kualitas perairan, sehingga tercipta ketidakseimbangan antara komponen organik dan anorganik dalam lingkungan budidaya. Dinamika kualitas air yang terjadi di dalam tambak menjadi momentum untuk pertumbuhan cyanobacteria atau yang lebih dikenal blue green algae (BGA). BGA dapat dibedakan berdasarkan morfologinya dan dapat dikelompokkan menjadi Chroococcales, Gloeobacterales, Nostocales, Oscillatoriales, Pleurocapsales, Spirulinales, dan Synechococcales. Oscillatoria sp. sering kali mendominasi komunitas fitoplankton, pada beberapa wilayah perairan Jawa. Berdasarkan data yang diperoleh dari PT. Indonusa Yudha Perwita, Indramayu selama empat siklus pemeliharaan, genus Oscillatoria sp. merupakan genus yang mendominasi media budidaya. Data beberapa siklus terdahulu yang diperoleh dari PT. Sumur Unggul Persada, juga menunjukkan adanya dominansi Oscillatoria sp. di dalam media budidaya. Dominansi BGA pada media budidaya udang berkorelasi positif dengan terjadinya outbreak penyakit. Populasi BGA yang meningkat menyebabkan kegagalan berbagai jenis fitoplankton dalam berkompetisi memperoleh nutrien. BGA dapat hidup dalam kondisi lingkungan yang kurang menguntungkan karena dapat memanfaatkan N2 dari atmosfer ke dalam bentuk yang lebih sederhana sehingga dapat dimanfaatkan, melalui proses fiksasi nitrogen. Tujuan dilakukannya penelitian ini yaitu mengevaluasi hubungan kelimpahan BGA jenis Oscillatoria sp. terhadap kualitas air budidaya, kinerja produksi, aktivitas respons imun, dan antioksidan pada udang vaname. Menghasilkan manfaat berupa informasi tentang ambang batas aman kelimpahan Oscillatoria sp. serta interaksinya dengan berbagai parameter kualitas air, sehingga dapat dijadikan dasar dalam skema pergantian dan pengelolaan air di tambak, guna meningkatkan produktivitas budidaya. Penelitian dilaksanakan pada rentang bulan Juli 2024 November 2024. Sampel air berisi fitoplankton diperoleh dari PT. Indonusa Yudha Perwita, Indramayu, Jawa Barat. dan PT. Sumur Unggul Persada, Banten, Jawa Barat. Pemeliharaan hewan uji dilakukan di Laboratorium Marikultur, IPB University, isolasi dan pemeliharaan Oscillatoria sp. di Laboratorium Lingkungan Biologi, IPB University. Analisis kualitas air dilaksanakan di Laboratorium Lingkungan Akuakultur, IPB University. Analisis histologi di Laboratorium Patologi SKHB, IPB University dan status kesehatan udang dilakukan di Laboratorium Kesehatan Organisme Akuatik, IPB University. Terdapat dua tahapan pada penelitian ini yaitu, isolasi dan proses pemeliharaan Oscillatoria sp. serta pemeliharaan udang vaname dalam wadah yang ditambah Oscillatoria sp.. Isolasi dan proses pemeliharaan dilakukan dalam laboratorium terkontrol dengan tujuan menghasilkan inokulan murni Oscillatoria sp. yang digunakan sebagai bahan uji pada tahap selanjutnya. Tujuan dilakukannya proses pemeliharaan udang vaname pada wadah yang ditambahkan Oscillatoria sp. yaitu untuk mengevaluasi dampak kelimpahan Oscillatoria sp. terhadap kualitas air dan kinerja produksi udang, melalui beberapa parameter kualitas air (kimia, fisika, dan biologi), status kesehatan udang serta aktivitas antioksidan. Rancangan penelitian yang digunakan yaitu Rancangan Acak Lengkap (RAL) dengan 4 perlakuan dan 3 ulangan yang terdiri dari P0 atau kontrol (tanpa penambahan Oscillatoria sp.), P4 (air laut + Oscillatoria sp. hingga kelimpahan 104 ind mL-1), P5 (air laut + Oscillatoria sp. hingga kelimpahan 105 ind mL-1) dan P6 (air laut + Oscillatoria sp. hingga kelimpahan 106 ind mL-1). Parameter uji yang dilakukan meliputi analisis tingkat kelangsungan hidup, rasio konversi pakan, laju pertumbuhan spesifik, analisis deskriptif, total haemocyte count, indeks keanekaragaman fitoplankton, analisis komparatif dan kompratif lanjutan, analisis korelasi dan analisis multivariant berupa dendrogram. Hasil penelitian ini menunjukkan bahwa keberadaan Oscillatoria sp. mempengaruhi kualitas air dan kinerja produksi pada udang vaname. Hal tersebut ditandai dengan adanya penurunan kualitas air budidaya terutama pada parameter kimia dan biologi berupa pH, alkalinitas, serta kelimpahan koloni Vibrio sp.. Terlihat rendahnya biomassa akhir, bobot akhir individu, pertumbuhan bobot mutlak, serta laju pertumbuhan spesifik, pemanfaatan pakan kurang efisien yang ditandai dengan nilai rasio konversi pakan yang cenderung tinggi. Perubahan aktivitas respons imun dan antioksidan terjadi akibat adanya stres lingkungan, serta ditemukan kerusakan pada gambaran organ hepatopankreas dan usus. Kualitas air yang menurun menyebabkan stres pada udang yang dapat mempengaruhi produktivitas budidaya. Berdasarkan hasil penelitian ini penting untuk dilakukan pengelolaan kualitas air, seperti pergantian air budidaya sebelum kelimpahan Oscillatoria sp. mencapai 105.

The high demand for Litopenaeus vannamei (whiteleg shrimp) has led to increased shrimp production across nearly all parts of the world, including Indonesia. To achieve higher yields, stocking densities have been increased, and intensive to super-intensive systems are commonly adopted in modern shrimp farming practices. These intensive systems rely heavily on artificial feeds to support shrimp growth throughout the cultivation process. However, this approach has resulted in the accumulation of feed waste at the pond bottom. The presence of residual feed waste on the pond floor contributes to fluctuations in water quality, leading to an imbalance between organic and inorganic components within the aquaculture environment. This water quality dynamic creates favourable conditions for the proliferation of cyanobacteria, also known as blue-green algae (BGA). Cyanobacteria can be morphologically classified and grouped into various orders, including Chroococcales, Gloeobacterales, Nostocales, Oscillatoriales, Pleurocapsales, Spirulinales, and Synechococcales. Among them, Oscillatoria species often dominate the phytofitoplankton community in several aquatic regions of Java. According to data obtained from PT. Indonusa Yudha Perwita in Indramayu over four cultivation cycles, Oscillatoria spp. consistently dominated the culture medium. Similarly, data from previous cycles at PT. Sumur Unggul Persada also showed the dominance of Oscillatoria spp. in shrimp pond environments. The dominance of BGA in shrimp culture media has shown a positive correlation with disease outbreaks. An increase in BGA populations hinders the survival of various other phytoplankton species by outcompeting them for essential nutrients. BGA can thrive in unfavourable environmental conditions due to its ability to utilize CO2 during photosynthesis to produce oxygen, as well as convert atmospheric nitrogen (N2) into more bioavailable forms through nitrogen fixation. This study aims to evaluate the relationship between the abundance of BGA, specifically Oscillatoria sp., and aquaculture water quality, shrimp growth performance, immune response activity, and antioxidant levels in L.vannamei. The study is expected to provide insights into the safe threshold levels of Oscillatoria sp. abundance and its interactions with various water quality parameters. These findings will serve as a foundation for water management strategies in shrimp farms to enhance aquaculture productivity. The research was conducted from July 2024 to November 2024. Water sampels containing phytoplankton were collected from PT. Indonusa Yudha Perwita, Indramayu, West Java, and PT. Sumur Unggul Persada, Banten, West Java. Experimental shrimp cultivation at the Mariculture Laboratory, IPB University, while Oscillatoria sp. cultures was maintained at the Environmental Biology Laboratory, IPB University. Water quality analysis was performed at the Aquaculture Environmental Laboratory, IPB University, histological analysis at the Pathology Laboratory, SKHB, IPB University, and shrimp health status assessment at the Aquatic Organism Health Laboratory, IPB University. This study was conducted in two stages: the isolation and culture of Oscillatoria sp., and the cultivation of L.vannamei in containers supplemented with Oscillatoria sp. The isolation and culturing processes were carried out in a controlled laboratory setting with the aim of producing a pure Oscillatoria sp. inoculum to be used as a test material in the subsequent experimental phase. The purpose of shrimp cultivation in containers supplemented with Oscillatoria sp. was to evaluate the impact of Oscillatoria sp. abundance on water quality and shrimp production performance, using several parameters including water quality (chemical, physical, and biological), shrimp health status, and antioxidant activity. The research design follows a Complete Random Design (CRD) with four treatments and three replicates: P0 (control, no Oscillatoria sp. addition), P4 (seawater + Oscillatoria sp. at 104 cells mL?¹), P5 (seawater + Oscillatoria sp. at 105 cells mL?¹), and P6 (seawater + Oscillatoria sp. at 106 cells mL?¹). Data analysis includes survival rate, feed conversion ratio (FCR), specific growth rate (SGR), descriptive analysis, total hemocyte count (THC), phytoplankton diversity index, comparative and advanced comparative analysis, correlation analysis, and multivariate dendrogram analysis. The results of this study indicate that the presence of Oscillatoria sp. affects water quality and the production performance of L.vannamei. This is evidenced by a decline in water quality, particularly in chemical and biological parameters such as pH, alkalinity, and the abundance of Vibrio sp. colonies. A decrease was also observed in final biomass, individual final weight, absolute weight gain, and specific growth rate. Feed utilization was less efficient, as indicated by a tendency toward higher feed conversion ratios. Changes in immune response activity and antioxidant levels occurred as a result of environmental stress, and tissue damage was observed in the histological structure of the hepatopancreas and intestine. The deterioration of water quality caused stress in the shrimp, which negatively impacted aquaculture productivity. Based on the findings of this study, it is essential to implement effective water quality management. Water exchange in the culture system should be carried out before the abundance of Oscillatoria sp. reaches 105 individuals each milliliter.