Keragaman dan struktur kumpulan ikan di anak sungai-anak sungai Sopokomil, Dairi, Sumatera Utara [Fish diversity and assemblage structure in tributaries of Sopokomil River, Dairi, North Sumatra] - Charles P.H. Simanjuntak (Masyarakat Iktiologi Indonesia (Indonesian Ichthyological Society), 2012)
Diversity and fish assemblage structure of Sopokomil tributaries was investigated on August and November 2010 with aims to describe spatial and temporal variation of the fish assemblage and evaluate environmental influence on fish distribution in Sopokomil tributaries. Seventeen sites were sampled using backpack electrofishing with single-pass depletion method. Throughout the study, sixteen fish species belonging to 10 genera and 8 families were collected. Species richness and diversity significantly increased from upstream, middle stream and downstream. Based on analysis of similarities (two-way ANOSIM), fish assemblages were significantly different in spatial variation but not in temporal variation. Canonical correspondence analysis (CCA) highlighted four environmental variables (altitude, total suspended solid, dissolved oxygen, and temperature) significantly structuring fish assemblages in the tributaries of Sopokomil River. Total suspended solids in streams increases by anthropogenic activities along the tributaries. The status of protected forest which is cover upstream and part of middle stream of Sopokomil River needs to maintain for ichythyofauna preservation. Abstrak Penelitian tentang keragaman dan struktur kumpulan ikan yang dilakukan pada bulan Agustus dan November 2010 di anak sungai-anak sungai Sopokomil bertujuan mendeskripsikan komposisi dan keragaman kumpulan ikan secara spasial dan temporal serta mengevaluasi faktor lingkungan utama yang memengaruhi distribusi ikan di lokasi tersebut. Penangkapan ikan menggunakan alat backpack electrofishing dengan metode single-pass depletion di tujuh belas stasiun pengamatan. Ikan yang ditemukan selama penelitian berjumlah 16 spesies dari 10 genera dan 8 famili. Kekayaan spesies dan keragaman ikan meningkat secara signifikan mulai dari zona hulu, tengah, dan hilir. Hasil uji two-way ANOSM tanpa replikasi menunjukkan bahwa kumpulan ikan secara spasial berbeda secara signifikan, namun tidak berbeda secara temporal. Canonical correspondence analysis (CCA) menggarisbawahi bahwa ada empat parameter lingkungan uta-ma yang signifikan memengaruhi struktur kumpulan ikan di anak sungai-anak sungai Sopokomil, yakni ketinggian, pa-datan tersuspensi total, oksigen terlarut, dan suhu. Beberapa aktifitas antropogenik ditengarai ikut mengambil peran da-lam meningkatkan kandungan total padatan tersuspensi di badan sungai. Status hutan lindung yang melingkupi daerah hulu dan sebagian bagian tengah Sungai Sopokomil perlu untuk tetap dipertahankan demi kelestarian iktiofauna sungai ini.