Assessing Benthic Community and Water Quality as the Bioindicator of Environment in Semayang Lake East Kalimantan, Indonesia

Lake Semayang is a floodplain lake with an area of ±13,000 ha. Over time, this lake has experienced a lot of ecological pressure due to anthropogenic changes that have an impact on the condition of the waters in it. Water quality is highly dependent on the presence of aquatic biota. One of the aquatic biotas that are very important in determining the condition of the waters is the benthos, namely animals that live on the bottom of the waters and are bioindicators from a biological point of view. The methodology is by taking benthic samples in the field using the Ekman Grab, identifying, and analyzing the calculation of abundance, diversity, and looking at the condition of the surrounding waters. This paper describes the presence of benthic macroinvertebrate communities as bioindicators of aquatic health. The research was conducted from March to October 2018 at five observation stations with purposive sampling. The results showed that the highest macrozoobenthos communities were in the families Tubificidae and Thiaridae, namely Branchiura sowerbyi and Melanoides sp. The presence of B. sowerbyi and Melanoides sp indicates that the condition of the waters is still in the good category with moderate diversity values, rich in organic matter with low dissolved oxygen (DO) conditions, and high suspended particles.