Study On Community Structure And Species Diversity Of Fish Assemblage In The Coastal Waters Of Jiaozhou Bay

Jiaozhou Bay, which locates in the south of Shandong peninsula, is a semi closednatural bay extending from the Yellow Sea. It serves as an excellent spawning andfeeding ground for fishes and other invertebrate animals, and it is a very importantecosystem with high productivity and biodiversity. However, as to the high fishingactivity, marine environmental change, and the effect of global warming, majorchanges have been taken place in this area. Fish samples taken from March2009toFebruary2010with setnet in the shallow waters of Jiaozhou Bay were analyzed. Theresults showed that there were44species of fishes (young of the year) in this area,which belong to9orders,24families and39genera. Fish species belonging toPerciformes were most abundant (25species), which occupied56.8%of the totalnumber of fish species. There were23warm temperate fish species (52.27%of thetotal),14warm water species (31.82%) and7cold temperate species (15.91%); therewas significant differences between season as for temperature adaptive type of fish.There were36demersal fish species accounting for81.82%of the total with8pelagicfish species (18.18%). According to the diversity of spawning, there were21pelagicegg fish species (47.73%),9demersal egg species (20.45%),9adhesive egg fishspecies (20.45%), and5ovoviviparity fish species (11.36%). There were obviousseasonal alternations in fish species composition, and the average seasonal rate ofspecies replacement was63.3%. The dominant species changed monthly andseasonally. The young fish of blue scad Decapterus maruadsi was found in theshallow waters of Jiaozhou Bay in this survey, indicating that its spawning groundwas moved north, which might be due to the water warming in the Yellow Sea. Therewas a small amount of young fishes of some commercial fishes, such asEupleurogrammus muticus, Argyrosomus argentatus, and Larimichthys polyactiscaptured in this survey, which maight be caused by overfishing and environmentalchange. The young fish of more than40fish species were captured, including manycommercially important species such as Sebastods schlegeli, Pseudopleurnectes yokohamae, which indicated that Jiaozhou Bay was still an important spawning andnursery field and various fish species seemed to use this sea area alternately. In orderto achieve sustainable development of fisheries, measures should be taken to preservethe ecological environments and fishery resources.The results show that there were44species of fishes (young of the year) in thisarea, of which27species were marine fishes, and the rest17species were estuaryfishes. The fish composition of Jiaozhou Bay has closely relation with temperatureand salinity. The temperature of Jiaozhou Bay in whole year was range form-0.57to25.55℃, while the value of salinity was range from29.58to31.57at the same time.The Marglef abundance index (R) of fish composition in Jiaozhou Bay were rangefrom0.33to3.50, and the Shannon-Wiener diversity index (H) were range from0.42to2.25, the Pielou index (J) were range from0.23to0.93. According to theCluster and MDS analysis, three month-groups of fish samples were classified,include GⅠ with lowest water temperature(1,2,3,4,12), GⅡ with high temperature（5,6,10,11） and GⅢ with highest temperature（7,8,9）. Syngnathus acus, Enedriasfangi, Ammodytes personatus and other resident cold temperature ecological typeswere key species in GⅠ, Engraulis japonicus and Syngnathus acus were keyspecies in GⅡ, Scomber japonicus, Apogonichthys lineatus, Acentrogobius pflaumiiand other migration fish were key species in GⅢ. The ANOSIM analyze showed thatthe Community structure of these3groups has significant difference. The BIOENVanalyze showed that water temperature was critical factors that affected the fishdiversity in Jiaozhou Bay. About40larval fish species were founded in Jiaozhou Bay,however, the low value fishes occupy the main part, which indict that the ability ofspawning and nursery in Jiaozhou Bay have been decline recently. The protection andrepair of ecological environment and fishery resources in the coastal waters ofJiaozhou Bay should be improved.