Mangrove Vegetation and Water Quality Conditions in the Coastal Area of Seruyan Regency, Central Kalimantan

摘要

The aim of this study was 1) to assess the mangrove vegetation condition from mangrove distribution and composition and Importance value index (IVI), and 2) to assess the water quality from physico-chemical parameters and primary productivity in the coastal waters of Seruyan Regency. The study was carried out from December 2012 to May 2013, on 3 mangrove zones or habitats in the coastal area of Seruyan Regency, Central Kalimantan, i.e. Zone I (Sungai Bakau Village), Zone II (Kuala Pembuang II Village); and Zone III (Sungai Gintung Village). Data were obtained by Line Tansect Plot method, population sampling of an ecosystem with sample plot approach along the line put from the coastal line toward the land. Vegetation diversity showed that mangrove distribution in the study site was structured by 5 species, Avicennia marina, Excoecaria agallocha L, Nypa fruticans, Rhizophora apiculata, and Sonneratia caseolaris. Zone I (Sungai Bakau village) had 16 individuals (69.6%) of N. fruticans and 7 individuals (30.4%) of S. caseolaris, with a density of 6 ind/100 m². Zone II (Kuala Pembuang II village) had 66 individuals (89.2%) of A. marina,4 individuals (5.4%)of E. agallocha and 4 individuals (5.4%) of R. apiculata, with a density of 15 ind/100 m². Zone III (Sungai Gintung village) had only A. marina as many as 30 individuals (100 %). The mangrove density was 10 ind/100 m². Moreover, the importance value index in zone I was 151.4 for N. fruticans and 148.6 for S. caseolaris. In zone II, the highest IVI occurred in A. marina (231.7), followed by E. agallocha (50.0) and Rhizophora apiculata (18.3). In zone III, since A. marina was the only spesies found, the IVI was 300.0. Mangrove productivity was 100 gr C/m²/yr in zone I, 63.98 gr C/m²/yr in zone II, and 35.36 gr C/m²/yr in zone III, respectively. Physico-chemical parameters, such as temperature, pH, DO, and total suspended solid still met the provision of Minister’s Decree for Living Environment No. 51, 2004. Except that nitrate (N-NO₃) and phosphate (P-PO₄) exceeded provision of seawater quality standard, 0.008 mg/l for nitrate (N-NO₃) and 0.015 mg/l for phosphate (P-PO₄).