Meiofauna and nematode communities in a sandy beach and in the sandbars of an adjacent creek on the Odisha coast, India

Abstract

This study investigated the distribution of meiofauna (45–500 μm) in the intertidal zones of a tropical, mesotidal sandy beach of Gopalpur coast and sandbars of Haripur creek, on the Odisha coast, India. Sediment samples were collected from the sandy beach at each tidal level (high to low) and from the sand bar of Haripur creek during the southwest monsoon (July-September 2019). Altogether, nine meiofaunal taxa were recorded with a mean abundance of 258 ± 213 ind. 10 cm⁻². Crustaceans and polychaetes dominated the meiofaunal community (59%), followed by nematodes (18%). Meiofaunal abundance varied significantly across tidal levels and sediment depths, peaking in the low tide zone and in subsurface sediment layers, while reduced abundance was observed in areas influenced by anthropogenic disturbance. The horizontal distribution of meiofauna was controlled by sediment grain size, air temperature, water exposure time, and organic matter content, whereas vertical distribution was shaped by sediment porosity, water percolation, oxygen availability, and species specific adaptations. Nematodes comprised 12 families and 14 genera, dominated by Comesomatidae, Oncholaimidae, and Xyalidae. The distribution of their feeding guilds across subsurface layers suggest niche partitioning within the sediment column, indicating trophic segregation linked to resource availability and sedimentary conditions. Variations in the meiofaunal abundance and distribution pattern, along with the low functional diversity of nematodes in the creek sandbars, were consistant with the low habitat heterogeneity. The observed variation in meiofaunal distribution compared with those reported in similar studies suggests that tropical mesotidal dissipative beaches possess distinct ecological characteristics, mainly governed by local climate and beach morphodynamics.