Polychaete–sediment relations in Rayong, Thailand

Accumulation of organic wastes in intensive shrimp culture ponds and nearby coastal waters has become a serious problem of environmental and economical concern in Thailand. As a first step towards managing organic waste accumulated in sediments via bioturbation by marine benthic polychaetes, an investigation was carried out using naturally occurring polychaetes in a tidal flat of Rayong, a province located in the eastern part of Thailand. The sediments were composed mainly of muddy sands and received mild organic loading from nearby communities. There were two dominant species of polychaetes: Notomastus sp. (Capitellidae) and Perinereis sp. (Nereididae). Studies of population size indicated that the appropriate sediment conditions for maximum growth of Perinereis were 17.5–20.0% water content, 1.75–2.00% total organic matter content, and 0.10–0.15 mg/g acid volatile sulfide content. Abundances of Perinereis were negatively correlated with water content of the bottom sediments. In contrast, even the highest levels of organic enrichment were still suitable for Notomastus. Because the abundance of Notomastus was positively correlated with high sediment organic levels, this species was considered to have potential for waste management via bioturbation.