FAKTOR-FAKTOR LINGKUNGAN ABIOTIK DAN KEANEKARAGAMAN PLANKTON SEBAGAI INDIKATOR KUALITAS PERAIRAN DANAU TOBA (Environmental Abiotic Factors and the Diversity of Plankton as Water Quality Indicators in Lake Toba, North Sumatera, Indonesia)

Abstract

ABSTRAK Penelitian ini bertujuan untuk mengetahui faktor-faktor lingkungan dan keanekaragaman plankton sebagai indikator kualitas perairan Danau Toba, Sumatera Utara. Penelitian ini dilaksanakan pada bulan April – Mei 2003 pada 3 stasiun pengambilan sampel (Parapat, Simanindo dan Balige). Dari hasil penelitian diidentifikasi sebanyak 93 genera plankton (7 kelompok fitoplankton dan 2 kelompok zooplankton). Dari hasil perhitungan nilai indeks keanekaragaman Shannon-Wiener memperlihatkan bahwa komunitas plankton di ketiga lokasi pengamatan adalah mirip. Nilai indeks keanekaragaman menunjukkan bahwa perairan mengalami pencemaran sedang. ABSTRACT The aim of the study is to investigate the environmental abiotic factors and the diversity of plankton as water quality indicators in Lake Toba ecosystem, North of Sumatera. The study was done on April to May, 2003 in three sampling stations (Parapat, Simanindo and Balige). Ninety three genera of plankton (seven groups of phytoplankton and two groups of zooplankton) were identified. The calculated values of diversity index (Shannon-Wiener) showed that plankton community in three stations is quite similar. The scores of diversity index were categorized into moderately polluted by organic matters.