Characteristics of habitat and distribution of ragworm Tylorrhynchus heterochaetus (Quatrefages, 1866) (Nereididae: Phyllodocida) in the soil ecosystem of the Hai Duong area, Vietnam

Abstract

This study on ragworm species Tylorhrynchus heterochaetus (Quatrefages, 1866) (Nereididae: Phyllodocida) focuses on the biological development and vertical distribution of ragworm (Nereididae: Tylorrhynchus heterochaetus) in soil ecosystem of Hai Duong, Vietnam. The study contains five habitats types: Thai Binh river bank, ragworm rearing rice field, Dike, Grassland and Cultivated field. Ragworm species (Tylorrhynchus  eterochaetus) was recorded in only the ragworm rearing rice field which is affected by sea level rise. In this habitat, ragworm was recorded in the all four seasons of the year, concentrating mainly in late spring and autumn. The ragworm is distributed in the surface soil vertical layers of 0 - 50 cm and more concentrated at the depth of > 10 - 30 cm. The habitat of ragworm has a sandy or clay foundation, pH = 7 - 9, salinity 0.2 - 0.3 ‰, with a high temperature variation.