Study On Species Diversity And Community Characters Of Marine Organisms In The Seas Near The Oufei Beach In Wenzhou

In order to research the quality of marine ecological environment in the seas near the Ou-fei beach in Wenzhou, the community structure such as species composition, dominant species, diversity of plankton, benthos, nektons were analyzed based on the investigation in spring of2011and2013. The main results were as follows:(1) planktonThe species number of phytoplankton, zooplanktonin spring of2013was63and65respectively. The average biodiversity index H’was2.34and2.66. The condition of overall habitat was normal. The diversity, evenness and richness of phytoplankton in the same area showed minor difference between2011and2013. But the dominant species was Rhizosolenia hyalina, Ceratium tripos ect in2013, while that in2011was Skeletonema costatum, Synedra etc. The species number, biodiversity, evenness and richness of zooplankton were equally matched with that in2011. However, the population density increased obviously, while the biomass dropped significantly. The dominant species had switched to Obeliageniculatalinne, Corycaeus qffinis etc from Pleurobrachia globosa, Calanus sinicus etc.(2) benthosThe species number of benthos and intertidal benthos in spring of2013was59and101respectively. The average biodiversity index H’was2.43and2.35. The condition of overall habitat was normal. The species number, density, biomass and biodiversity index of benthos all increased in some extent. Moreover, the polychaetes replaced mollusc as the ascendent group in the community composition. And the dominant species was Potamocorbula ustulata and Mediomastus, which was Nassarius succinctus and Sternaspis scutata before. The biodiversity level of intertidal benthos declined while its richness increased. The species number, diversity and biomass all went up greatly. The dominant species had changed into Chthamalus stellatus, Vignadula atrata etc from Nerita yoldii and Thais clavigera.(3) nektonThe results showed that58species were identified in2011, including35species of fishes,21species of crustaceans,2species of cephalopoda. The dominant species were Oratosquilla oratorio, Palaemon gravieri and Collichthys lucidus. The overall level of biodiversity was general in the the area near the Ou-fei beach. ABC curve results showed that the community structure of nekton had been affected moderately.While87species were identified in2013, including55species of fishes,28species of crustaceans,4species of cephalopoda. The dominant species were Amblychaeturichthys hexanetna, Pampus argenteus and Harpodon nehereus. The level of biodiversity was general, and the richness was high. However, ABC curve results showed that the community structure of nekton had been affected seriously. And the lever of biodiversity was lower at the Estuary of Ou River and Feiyun River and the offshore area.Within the same range, a total of73species of nekton were identified in2013, more than in2011. The species composition had changed, fish species composition changed obviously, the species didn’t appear together was13and24respectively in2011and2013.Compared to2011, the dominant species had changed, the percentage of the total catches had increased, while the total mantissa percentage had increased significantly. The IRI of some economic species had decreased, such as Coilia mystus, Collichthys lucidus, Palaemon gravieri and so on. While the IRI of Amblychaeturichthys hexanema had increased significantly. The community structure of nekton had been affected more seriously than in2011. The results of cluster analysis showed that the similarity of nekton community was low in two years, and the community structure had changed. The biodiversity index H’and evenness index J in2013had increased slightly than in2011, but the richness index D had decreased obviously.Compared to2011, the average mantissa density increased obviously in the spring of2013, while the weight density decreased. The average resource density of crustaceans decreased significantly, and that of Cephalopods decreased, too. The percentage of the species that mantissa density was more than1×103ind./km2and weight density was more than10kg/km2had decreased in the total number of species. The resource density of some species decreased, such as Palaemon gravieri, Sardinella aurita, Coilia mystus. While the resource density of Amblychaeturichthys hexanema, Engraulis japonicus increased significantly, and mantissa density increased sharply. The resource density of Pampus argenteus also increased.In conclusion, the eco-environmental quality of plankton and benthos was getting worse, and nekton resources were not good. The eco-environmental quality of the seas near the Ou fei beach was getting worse.