Distribusi, struktur trofik, dan pertumbuhan ikan di Sungai Cisadea, Kabupaten Cianjur, Jawa Barat

Abstract

Pengkajian komunitas ikan di perairan Sungai Cisadea bertujuan untuk mengkaji struktur komunitas ikan serta mengelompokan berbagai anggota komunitas tersebut berdasarkan makanannya. Selain itu kajian pola pertumbuhan dan faktor kondisi bagi kehidupan ikan yang mendominsi sungai ini juga dilakukan. Penelitian ini dilaksanakan di Sungai Cisadea dari bulan Juli 2012 sampai Februari 2013. Sampel ikan ditangkap menggunakan alat tangkap aktif (Electrofishing Gear, jala tebar, serok, anco) dan pasif (bubu) dari bagian hulu (LC1), tengah (LC2) dan hilir (LC3). Hasil penelitian menunjukan bahwa kualitas fisika kimia perairan masih berada pada kisaran normal yang dapat mendukung kehidupan ikan. Komunitas ikan di perairan Sungai Cisadea terdiri atas 11 ordo, 26 famili, 35 genus dan 48 spesies. Rhyacichthys aspro dan Glyptothorax plathypogon merupakan spesies dominan tertangkap selama penelitian. Nilai indeks keanekaragaman (H’) sebesar 2,87 dengan dominansi 0,09 dan kemerataan 0,74. Kesamaan komunitas berdasarkan kehadiran spesies menjadikan lokasi hulu (LC1) dan LC2 (tengah) berada pada satu kelompok dan lokasi hilir (LC3) berada pada satu kelompok yang terpisah. Selama pengamatan, komunitas ikan di Sungai Cisadea di dominasi oleh ikan omnivora dan karnivora. Berdasarkan spesialisasi makanannya, komunitas ikan di sungai tersebut terdiri atas insektivora, algivora, krustivora dan moluskivora.Di wilayah bagian hulu dan tengah sungai makanan utama komunitas ikan terdiri atas insekta dan alga, sedangkan dibagian hilir terdiri atas alga, insekta dan krustase. Pola pertumbuhan berdasarkan jenis kelamin dan lokasi pada ikan R. sapro dan G. plathypogon bersifat alometrik (b≠3). Faktor kondisi R. sapro jantan berkisar antara 0,35-1,91 dan betina berkisar antara 0,16-2,05, sedangkan faktor kondisi G. Plathypogon jantan berkisar antara 0,71-2,66 dan betina berkisar antara 0,61-2,47.Berdasarkan lokasi, faktor kondisi tertinggi ditemukan di lokasi hulu (LC1.1) dan tengah (LC2.1) untuk R.aspro, sedangkan untuk G. Plathypogon hanya di lokasi hulu (LC1.1).

Study on fish communities in the river of Cisadea aims to assess the fish community structure and classify the various members of the community based on its food and to study the growth pattern and condition factor of fish which dominate in this river also performed. The research was conducted in the Cisadea River from Juny 2012 until February 2013. Samples of fish were caught using active fishing gear (Electrofishing Gear, fishnet stocking, ladle, anco) and passive fishing gear (traps). The results showed that the physics-chemical quality of water is still in the normal range that can support fish life. Fish communities in the Cisadea River consists of 11 orders, 26 families, 35 genera and 48 species. Rhyacichthys aspro and Glyptothorax plathypogon were the dominant species which caught in this research. Diversity index value (H') of 2,87, with the dominance and the evenness of 0,09 and 0,74, resvectively. Similarity index of community based on species presence made the upstream (LC1) and midstream (LC2) location were in one group and downstream location (LC3) was an another separate groups. During the observation, the fish community in the Cisadea river were dominated by omnivorous and carnivorous fish. Fish communities in this river consists of insectivores, algivores, krustivores and moluskivores based on food specialitation. The main food of fish community in upstream and midstream area of this river consists of insects and algae, furthermore, in downstream area consists of algae, insects and crustaceans. The growth patterns based on sex and location of R. aspro and G. plathypogon were allometric (b ≠ 3). Condition factor of both R. aspro male and female range of 0,35-1,91 and 0,16-2,05, resvectively. On the other hand the condition factor both of G. plathypogon male and female in about 0,71-2,66 and 0,61-2,47, respectively. Based on the location, the highest condition factor for R.aspro was found at upstream (LC1.1) and midstream (LC2.1) locations and for G. plathypogon just found at upstream (LC1.1) location.