Sublittoral Macrobenthos Community Structure of South-Western Sarawak Coastal Waters : A Case Study in Kuching Wetland National Park (KWNP) and Adjacent Area

A survey on the macrobenthos community structure that covered II stations was carried out at the sublittoral area of the South-Western part of the Sarawak including the river mouth of the Kuching Wetland National Park (KWNP), RAMSAR site. Bottom water and sediment samples were collected using water and sediment samplers. The in situ physicochemical parameters were collected using multi-parameter. Results of the one-way analyses of similarity indicated that the in situ physico-chemical parameters were significantly different between stations and a total of 43 species (include 2 unidentified species) had been recorded. BioEnv analysis had indicated eight parameters Total organic matter (TOM), chlorophyll a (ChI. a) in sediment, particle size (1 mm, 0.25 mm and < 63 ~m- clay), inorganic phosphorus (IP), depth and transparency were affecting the community structure of macrobenthos along the South-Western coast. Recently, the interest of public and stakeholders were focus on the environmental status of Kuching Wetland National Park (KWNP) due to the increase of urbanization processes and anthropogenic activities. A field sampling which covered 10 stations was conducted at the outer and inner boundary of KWNP in August 2011 during high tide. Water and sediment samples were collected using the methods mentioned above. One-way analyses of similarity indicated that all the study sites were significantly different between stations (pvalue < 0.05) and boundaries (p-value < 0.05). Water temperature, pH, ammonium nitrogen (NH)-N) and IP were known affecting the abundance of phytoplankton (ChI. a) communities. The concentrations of nitrate-nitrogen (NO)-N) at the outer and inner boundaries of KWNP were over-ranged as compared to Malaysi~ marine standards. During the seasonal survey (April 20 II - March 2012) on macrobenthos community, a total of 35 IV environmental parameters was studied. In general, a two way ANOSIM was performed on all the mean environmental data (water and sediment quality) showed significant difference in both month and station. A total of 72 species had been documented throughout the study period. Polychaete was the dominant group of macrobenthos with a total of 78% followed by Malascostraca (18%). Results of the BioEnv showed that a total of five environmental variables were affecting the macrobenthos community in the present study (correlation = 0.435; p-value = 0.01). The results of the present study had identified the Capitella cf. capitella as the dominant species indicated the presence of potential "disturbances" that affecting the marine ecosystem of the area. The documentation on the free-living marine nematodes that falls in the macrobenthos categories had recorded two new species: Metalinhomoeus ramsarellsis sp. nov. and Trissonchulus bulbius sp. nov. The M. ramsarensis sp. nov was found in Kuching Wetland National Park (KWNP). The total body size of was extremely long. The head was recorded to be round with four cephalic setae followed by four sub cephalic setae. The inner and outer labial papillae were not clearly observed. An oesophageal bulb was present at the end of the oesophagus. Spicules were known to have central cuticularized strip. Tail of M. ramsarensis sp. nov. was short and blunt. Another new species, T. blilbius sp. nov. is closely resembles to T. jalletae and T. reverSllS in terms of the short, round and blunted tail with caudal gland that opened dorsally. The most distinct characteristic that distinguish the present species with T. janetae is the presence of bulb-like structure at the end of the oesophagus in the present species. Besides that, the distal end of the spicule of the present specimen forms a threepronged tip was never been reported in the other species