Preliminary Studies On Ecology Of Parasitic Nematodes From Several Marine Fishe From Yellow Sea, China

The parasitic nematodes of marine fishes form the Yellow Sea were investigated during May 2005 to September 2006. 930 fishes belonging to 94 species were examined for nematodes. 24,969 specimens were collected including 24,045 larvae and 923 adult worms. 6 types of larvae nematodes and 12 species of adult nematodes were identified. The structures of the communities and distribution pattern of various communities both larvae and adult nematodes were analyzed. The main results are as follows:1. The result of a community analysis on the nematode larvae of 7 main fish species showed Hysterothylaciumâ…¢larvae belongs to the core species with the highest prevalence and mean abundance. Hysterothylaciumâ…£and Anisakis type I also have a high prevalence. Hysterothylaciumâ… ,â…¡, Raphidascaris or Raphidascaroides type I belong to the satellite species. Among the 7 fish species, nematode larvae from Argyrosomus argentatus (Houttuyn) and Chelidonichthys kumu (the two hosts share a contiguous living habits and feeding range) have a similar community structure with rich larvae types and high intensity. The nematode larvae from Hyporhamphus sajori (Temminck & Schlegel) have the lowest abundance. The results indicated the certain relationships presented between the larvae abundance and its feeding range. The nematode larvae are in aggregation distribution inside the hosts.2. Investigations on the adult worms demonstrated a rather small proportion (which is only 3.7%) in the whole nematode communities. Hysterothylacium is most dominant in the adult worms. Whereas Hysterothylacium aduncum is the most dominant and widely distributed species among the 12 species of adult worms recorded from the hosts communities. While Hysterothylacium liparis n. sp. becomes the dominant species in its hosts. The sex ratio of the adult worms can be influenced by the abundance and interspecific competition to a certain extent.As mentioned above, the fish nematodes from Yellow Sea has a low species richness. The species of the genus Hysterothylacium are the dominant specie with much higher prevalence and intensity in the Yellow Sea. The structures of the nematode communities are dependant on the feeding habits of the host. Hysterothylaciumâ…¢is the dominant larvae species and Hysterothylacium aduncum is the dominant and generalist adult species.