Pengaruh pencemaran lingkungan industri terhadap keanekaragaman plankton, gastropoda dan bivalvia pada komunitas hutan mangrove tepi kali donan cilacap=The Impact of Industrial Pollution on Plankton,Gastropods and Bivalv

.The purpose of this research was to study the pollution of water found in mangrove forest alongside Donan River, by examining Physico-Chemical parameters of the water pollution ,such as heavy metals (Hg and Cd), sediments, gastropod\u27s and bivalvia\u27s meat, and biodiversity of those invertebrate and plankton. The research methods used for detecting heavy metals is Atomic Absorpsion Spectrophotometry (AAS), and biodiversity was identified according to Shannon Wiener. Charts were used for descriptive data analysis. The results for water quality indicate that temperature was about 28.0 - 31.33° C, pH was about 7 - 7.83salinity of 29.33 - 30.67 L, each was still an the natural approximation. The turbidity was 10.64 - 24.88 FTU, dissolved oxsigen was 3.55 - 6.47 ppm and mineral oil not detected (n.d) - 0.935 ppm which according to the Governor Decree of Central Java No. 660.1/26/1990 and the State Minister for Enviroment Decree No. 02/1/88, was still proper to be used for biota. The result for sea water indicates that mercury (Hg) was 0.0007 - 0.00312 ppm and cadmium (Cd) was 0.00345 - 0.03705 ppm. The contents had exceeded the limits of the standard quality of the sea biota established in the Governor Decree of Central Java No. 660.1/26/1990 and the State Minister for Environment Decree No. 02/1/88, the metals Hg was 5 0.003 ppm and Cd was 5 0.01 ppm. The result of sediment analysis for heavy metal detection, Hg was 0.01387 - 0.0658 ppm and Cd was 0.38686 - 0.91838 ppm, while the natural limited level for the sediment recommended by Resau National d\u27Obsevation for the metals Hg was 0.02-0.35 ppm and Cd was 0.1 - 2 ppm. The results of Gastropods (Nerita exuvia, Telescopium telescopium), and Bivalvia (Venus marcenaria, Lutraria australis) meat for heavy metals detection, gastropods Hg was 0.00128 -0.03555 ppm, Cd was 0.11042 - 0.54748 ppm and bivalvia Hg was 0.00809 - 0.04019 ppm and Cd was 0.20397 - 0.71496 ppm. The contents were still under the standard estabilished by Pengawasan Obat dan Makanan No. 03725/13/SK/V11/89, (for the metals was Hg 0.5 ppm and Cd was 1.0 ppm). Diversity index of plankton, Gastropods and Bivalvia observation station of the mangrove forest alongside Donan River Cilacap, that was less than two (< 2), means that these waters are polluted. Key. Words : Water Pollution, heavy metals Hg and Cd, diversity of plankton, gastropods and bivalvia