Species composition and distribution of Thaliacea(Tunicata) in the Beibu Gulf

WANG Xue-feng1,2,3,LI Chun-hou1,JIA Xiao-ping1,LIAO Xiu-li1(South China Sea Fisheries Research Institute,Chinese Academy of Fishery Sciences,Guangzhou 510300,China;2 Fisheries College,Guangdong Ocean University,Zhanjiang 524025,China;3 College of Marine Science,Shanghai Ocean University,Shanghai 201306,China)

Beibu Gulf;Thaliacea;abundance;biological characteristics

Based on the data of four seasonal investigations in the Beibu Gulf from Feb.in 1998 to May in 1999,the species/assemblage composition and their seasonal horizontal distributions of Thaliacea were analyzed,and their relations with their living environment were discussed.The results indicated that the Thaliacea in the Gulf included 12 species at least,among which the Doliolum denticulatum,Thalia democratica,Thalia decocratica orientalis were dominant species.The horizontal abundance of Thaliacea was 2.5,0.6,0.1,0.08 ind/m3 in spring,winter,summer and autumn respectively.The Canonical correspondence analysis showed that the abundance and its horizontal distribution were mainly influenced by the salinity of the Gulf,and less by the other factors(DO,sea surface temperature and pH).The coastal runoff,external sea water into the gulf mixed with the gulf water,of which seasonal variation greatly influenced the abundance and seasonal distribution pattern of Thaliacea.