The Community Characteristics Of Zooplankton Sampled With WP2Net In The Yellow Sea In Spring And Autumn,2012

The abundance of marine meso-and microzooplankton has always beenunderestimated due to the traditional sampling and analysis methods in China. Inorder to make up for the defect, zooplankton samples were collected with WP2plankton net in the Yellow Sea in May （spring）and November（autumn）,2012, andthe species composition, abundance and community structure of zooplankton wasstudied. This study help to get a comprehensive understanding of the marinezooplankton ecological characteristics, providing a more comprehensive detailedbasic data for the Yellow Sea of zooplankton ecology research.A total of133zooplankton species (not including28pelagic larvae) wereidentified during two surveys, the numbers of adult zooplankton species in spring (63)were less than that in antumn (119). The adult zooplankton species belong to Protozoa,Cnidaria, Ctenophora, Annelida, Mollusca, Arthropoda, Chaetognatha andUrochordata, respectively. The copepods, cnidarian and pelagic crustacean were thetop three largest groups in surveyed waters. They were accounted for39%,21%and17%of total species richness respectively.During spring, the average abundance of zooplankton (except Noctilucascientillans) in the Yellow Sea was8111.4ind/m3. The highest zooplanktonabundance was42176.8ind/m3at station B38in Bohai strait, and the abundancearound station B38was higher than that of other areas in Yellow Sea. That wasbecause of a large number of copepod Centropages abdominalis gathering in thatwaters. The low zooplankton abundance appeared in the southeast area of the survey.In autumn, the zooplankton abundance (average4331.0ind/m3, except Noctilucascientillans) was significantly reduced.The highest abundance20052.0ind/m3was atstation BF01, and the lowest abundance614.7ind/m3was at station H08. Thezooplankton abundance appeared a very uneven distribution in the North Yellow Sea,while the distribution of zooplankton abundance was even in the South Yellow Sea, and the zooplankton abundance in the North Yellow Sea was higher than that of theSouth Yellow Sea..The dominant zooplankton taxa were quiet different in the two surveys. Only twocopepod species Oithona similis and Paracalanus parvus were dominant zooplanktonin both seasons. In addition, the dominant species in spring survey also includedCentropages abdominalis, Calanus sinicus, Acartia clausi, Copepoda nauplii, andCentropages abdominalis was the most dominant species. The dominant species inautumn included Sagitta crassa, Oikopleura dioica, Bivalve larvae. The abundance ofCentropages abdominalis changed very much in the two seasons, it was2243.3ind/m3in spring survey, and reduced to0.9ind/m3during autumn survey.In spring, the average species number, Margalef’s richness index,Shannon-Weaner index and Evenness were23.5,2.58,2.09and0.46respectively.Biodiversity index of zooplankton showed a trend of increasing from north to south inthe survey area, expect for Jiangsu coastal waters where the value was low. In autumn,the values was31.5,3.71,2.21and0.45, respectively. The distributions of the valuesin autumn were similar to spring survey. The values of different biodiversity indexesin autumn were higher.In the two surveys, four communities of zooplankton were distinguished byusing the method of cluster analysis: the North Yellow Sea community, located in theNorth Yellow Sea and south off Chandong peninsula; the Yellow Sea centralcommunity, including most positions of the South Yellow Sea and a few positions ofthe North Yellow Sea; the Subei neritic community, located in the northern Jiangsucoastal waters; the South Yellow Sea inshore mixed water community, located in themixed waters of the Yellow Sea and the East China Sea. The Yellow Sea centralcommunity contained the most stations and the highest value biodiversity index ofzooplankton. The Subei neritic community included the minimum position andbiological diversity.Compared with the previous data collected with traditional plankton net (meshsize of505um), the zooplankton abundance and dominant species sampled with WP2plankton net was obvious different. In this study zooplankton abundance was much higher, Small size zooplankton were dominant instead of the bigger ones and smallcopepods accounted for absolute advantage. But there was no significant differencefor the community structure of zooplankton.