Struktur komunitas dan status fungsional organisme bentik makroinvertebrata pada Danau Singkarak, Sumatra Barat

Lake Singkarak is a tectonic lake which is located in West Sumatera. Nowadays the lake is facing serious problems such as lowering water discharge, decreasing indigenous species of fish population, and mesotropic water quality condition of the lake. Those conditions cause adverse effects to the endemic fish such as ikan bilih (Mystacoleucus padangensis) and other aquatic biota especially macroinvertebrates. The aims of this study are: 1). To know the composition and diversity of the maroinvertebrate in lake Singkarak, 2). To elucidate the correlation between. environmental variabels and the spatial distribution arrangement of the maroinvertebrate in lake Singkarak, 3). To understand the functional feeding status of the maroinvertebrate in lake Singkarak. Samples were taken in September 2001 on 9 locations. Shannon­ Wiener biodiversity index was used to calculate the macroinvertebrates diversity. Multivariate analysis using PCA and RDA were conducted to discover environmental variables which characterize species composition. It was shown from the calculation of diversity index, that benthos diversity of lake Singkarak tend to be classified as medium level (H'= 1,847 to 2,4931). Functional feeding status of benthos in the lake generally was dominated by the scraper (molluscs) except St 1 (Sumpur) which was dominated by gatherer-collector. The result from multivariate analysis using PCA and RDA showed that Melanoides tuberculata tend to be characterized by high level of supeded solid, Total nitrogen, Total Phosphate, and Disolved oxygen