Water quality evaluation of some mangrove ecosystems with variations of time restoration in South Malang, East Java, Indonesia

The area of the mangrove ecosystem in the South Malang, East Java region of Indonesia has dropped from 2000 due to land conversion and human activities. The society and the government have sought to preserve mangrove plants. The goal of this study was to assess the quality of the mangrove ecosystem, particularly its results by observing water quality and analyzing the connection between human activities around the mangrove ecosystem and water quality. The research method was Ex Post Facto. Monitoring was carried out on five selected mangrove ecosystems in South Malang including Clungup Mangrove Conservation (CMC), Bajulmati, Kondang Buntung, Sendiki and Tamban. Sampling at each site is performed at many stations based on variations in the timing of the revegetation activities. Sampling for each station was carried out at three places as replications. The total number of samples is 30 samples. Water quality parameters of mangrove ecosystem was measured in this study including dissolved oxygen (DO), salinity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate, and orthophosphate. We also observed the human activities in the each sampling location using Hemeroby index. The results of study showed that the water quality in several mangrove ecosystems in southern Malang varied. In general, the salinity (0.0-26.3% o) and BOD (2.1-9.6 mg / L) have met the standard values for seawater quality for the benefit of marine life. DO levels that have met the quality standard value were only in the mangrove ecosystems of Kondang Buntung, Sendiki and Tamban (5.3-6.3 mg / L). Nutritional content in the waters of all mangrove ecosystems is high with Nitrate levels exceeding the government quality standards (0.17-1.96 mg / L). COD levels have a positive correlation with water salinity levels. The water quality was degraded by the mangrove environment with higher human activities. CMC and Bajulmati conservation practices have influenced the enhancement of water quality in the ecosystem of the mangroves.