KEANEKARAGAMAN MAKROZOOBENTOS SEBAGAI INDIKATOR KUALITAS PERAIRAN DANAU TOBA BALIGE KABUPATEN TOBA SAMOSIR TESIS

Lake Toba is the largest lake in Southeast Asia, lies in the Northern part of Barisan Mountain Range. The water surface of Lake Toba is 995 m above sea level and about 1129,7 Km wide, length 87 Km, and 455 m deep. The water of this lake is used not only for agriculture, drinking water, traditional market but also for quay wall. The people activities along this lake could influence its water quality, because the waste produced by those people activities is thrown to this river directly. The changes of those water qualities in the lake induce the change of macrozoobenthos community. For that reason, it is necessary to observe the Danau Toba water quality based on macrozoobenthos indicator. The aims of the research were to know the diversity of macrozoobenthic as bioindicator in Danau Toba and to determine the Danau Toba quality level in relation to physical-chemical and biologis of the lake. The research was carried out from December 2008 until February 2009 in Danau Toba Balige Toba Samosir. Sampel were collected from four stations by Purposive Random Sampling method. Surber net and Eckmann Grabb were used to taken the sampel. Samples were identified in Laboratory PSDAL, Department of Biology, Faculty of Mathematic and Natural Sciences of North Sumatera University. The result showed that there five classes within ten ordo, 17 family and 21 genera of Macrozoobenthic were found. Elimia sp has the highest density index with 77,77 individu/m founded in second station, and Haitia sp in fourth station has the lowest density index with 1,23 individu/m. The Highest Index Diversity (H’) was founded at the 4 station with 2,08 and the lowest value was founded at the 1 station with 1,71. According to the analysis of Pearson Correlation, pH, DO, Oxygen Saturation and COD has the positive correlated to the diversity of Macrozoobenthic, while Organic Substrat, Fosfat, Nitrat, BOD5 and Temperature has the negative correlated to the Diversity of Macrozoobenthic.