MEIOFAUNA IN THALE SAP SONGKHLA, A LAGOONAL LAKE IN SOUTHERN THAILAND

Abstract

Quantitative samples of soft-bottom sediment meiofauna were collected from a lagoonal lake (Thale Sap Songkhla, southern Thailand). Eighteen taxa were encountered. Nematoda was the most abundant (62-64%) at all stations and Sarcomastigophora was the second (18-33%). Copepoda usually was not abundant, but it tended to be more common at seagrass beds. Total meiofauna densities varied among stations and seasons. The highest densities were found at stations adjacent to organic discharge areas and seagrass beds. The mean densities ranged from 65 to 1596 ind 10 cm-2. Meiofauna was in high abundance during the transitional period between the SW monsoon and NE monsoon in October (36 to 2490 ind 10 cm-2), while the low abundance was during the post NE monsoon in January (32 to 477 ind 10 cm-2). The number of taxa increased slightly in October. Vertical distribution of each taxon occurred concurrently. The greatest abundance of meiofauna was noted in the upper 1 cm of sediment (32 to 6227 ind 10 cm-2). Meiofauna was an important food supply for larger epibenthic fauna in the area. Although water temperature, salinity, particulate organic matter and particle grain size did not show positive correlation with meiofauna densities, the combination of those major factors may control the meiofauna population in Thale Sap Songkhla.