Biological characteristics and effects of salinity on reproductive activities of marine worm (Tylorrhynchus heterochaetus, Quatefages, 1865) in summer season in Hai Phong – Viet Nam

Abstract

Tylorrhynchus heterochaetus (Quatrefages 1865) are not only an environmental indicator species, but also an economical aquatic animal. Production of this species mainly depends on natural exploitation, which currently decreases dramatically due to the changes of living environment, such as abuse of pesticide and salinization. The current study was conducted in order to understand the biological characteristics of T. heterochaetus in Hai Phong, Vietnam. Results showed that weight of ranged from 0.44 to 0.53 g. Length and number of node were different between tube worm and matured worm (10.60 and 4.81 cm, 61 and 166 nodes, respectively). The experiment was carried out with 11 of salt levels ranged from 2 – 20 ppt. to evaluate the effects of salinity on reproduction of T. heterochaetus. The results showed that 10 ppt. is optimum level for reproduction when it gave the best results of worm participate into reproduction (82.11%), the ratio of fertilization (85.33%), hatching (65.56%) as well as survival rate of larvae (69.56%). Artificial breeding of T. heterochaetus is feasible for large scale and having prospects.