Influence of salinity on the meiofaunal distribution in a hypersaline lake along the southeast coast of India

The present study highlights that seasonal salinity variability plays a significant role in meiobenthic distribution with special reference to nematode assemblages. Sediment and water samples were collected from Pulicat Lake, a hypersaline lake along the southeast coast of India during two seasons (Southwest Monsoon (SWM) and Northeast Monsoon (NEM)). Based on the salinity distribution, the lake is categorized into four regions, viz., southern inlet, central region, middle inlet, and northern inlet. Meiobenthic abundance was higher during SWM (226-12,206 Ind/10 cm²) than in NEM (640-10,424 Ind/10 cm²). The meiofaunal abundance was high in the central region during both the seasons, followed by the southern, northern, and middle inlet. The nematode was the dominant meiobenthic group, followed by copepod, polychaete, and foraminifera. Due to high organic matter, the central region was dominated by deposit feeding nematode species like Halalaimus longicaudatus and Terschellingia longicaudata. The southern and northern regions were dominated by free-living nematodes Rhabditis olitoria, Mesorhabditis capitata, Mononochus bastian, Paramononchus sp., Piranchulus sp., and Diploscapter cylindricus. Oncholaimus sp., a hypersaline indicator species, was reported from the middle inlet location. Statistical analysis suggests salinity as a critical parameter for the distribution and diversity of nematodes.