Evaluation of pond lands utilization and study of organic matter spatial distribution of Vanname shrimp (Litopenaeus vannamei) aquaculture in the coastal area of Lamongan Regency

Coastal areas have a wide range of resources that can be utilized in multiple ways. Land utilization of coastal areas has been done for various interests, one of which is for shrimp aquaculture (farming). Continuous shrimp farming activities will lead to environmental degradation, characterized by decreased water quality. Besides, the area or spatial arrangement of shrimp aquaculture development that does not pay attention to the environmental carrying capacity due to improper management can cause environmental problems with all aspects of its complications in a long period of time, one of which is the problem emerging from shrimp farming with the use of intensive technology. Intensive shrimp farming can produce organic wastes, primarily from the residual feed, feces, and dissolved matters discharged into waters that significantly affect the quality of the coastal environment. This study aimed to determine the distribution pattern of organic matters resulted from Vanname shrimp (Litopenaeus vannamei) aquaculture in the coastal area of Lamongan Regency. This study was conducted from January to March 2018. The study used a descriptive method with Geographical Information System (GIS) approach. The spatial distribution analysis of organic materials was carried out using geostatistical analysis, by interpolating point data into areas (polygons) using IDW method. The interpolation results of each water quality of the ponds, river, and coastal waters were arranged in the form of thematic maps. The value pollution load index (PLI) value of the shrimp farming activities was determined based on six main indicators, namely dissolved oxygen, BOD5, TOM, Ammonia, Nitrate, and Phosphate. Based on the results obtained, the highest spatial distribution value of organic matters was showed by the BOD parameter of 3.12 mg/l – 3.25 mg/l, included in the medium-polluted category. Meanwhile, the measurement result of the phosphate content as an indicator of water fertility ranged from 0.005 -0.006 mg/l. It suggests that the waters on the coastal area of Lamongan Regency are included in oligotrophic waters, indicating a low fertility rate. From the results above, it can be concluded that the largest pollution load index (PLI) value is contributed by the Biochemical Oxygen Demand (BOD) parameter while the smallest value is contributed by the phosphate parameter, signifying a low fertility rate in the coastal area.