The use of benthic macroinvertebrate community to evaluate the environment of Cirata Reservoir, in West Java, Indonesia

Abstract

Macroinvertebrate community reflects the condition of a freshwater ecosystem. This study examined the community structure of macroinvertebrates and the water quality based on the existence of the Family in the Cirata reservoir. Moreover, to understand its response to several environmental variables. Cirata reservoir is a part of the cascade reservoir which has been known significantly loaded with organic material. The data of Environment variables, macroinvertebrates, and sediment samples were collected in November 2017 from five sites of the reservoir. The sites were chosen between floating net cages and the outlet, which the first site was the nearest and the fifth site was the farthest from the cages. Macroinvertebrates were collected and identified based on standard guidance. Ekman grab was used for collecting the sediment samples from the depth of 1.5 to 5 m with three times repetition in each site. The environmental variables including pH, dissolved oxygen (DO), turbidity, total dissolved solid, oxidation-reduction potential, and conductivity were recorded on the spot using Water Quality Checker. Meanwhile, Total Organic Matter (TOM) of sediment were analysed in Research Center for Limnology LIPI. The relationship between environmental variables and macroinvertebrate were evaluated using Canonical Correspondence Analysis (CCA). Eighteen taxa comprising four orders were identified. The community is grouped into four categories, Chironomids (81.65%), Non-Chironomids (Culliculidae, Odonata) (1.01%), Gastropods (4.13%), and Annelids (13.21%). The finding shows that polluted-tolerant groups are dominantly found in Cirata which consists of Chironomids and Annelids. Moreover, the diversity of macroinvertebrate was ranged moderate to low between 1.75 to 3.282. While the abundance ranged between 600 to 1889 ind/m2 in each site. However, the ordination of CCA described that TOM tended to be related to the existence of the non-Chironomids group, On the contrary, other parameters such as pH, DO, and temperature influenced the presence of the Chironomids, Annelids (worm), and Gastropods.