Macrobenthic Functional Groups In The Bohai Sea

Based on the four cruises in July, November 2013 and May, November 2014, a total of 47 stations were set for analyzing the present situation of macrobenthos in the Bohai Sea. The community structure, abundance, bio-diversity and relationship between bio-diversity and environmental factors, were analyzed. The functional groups and best environmental factors combination affecting macrofauna were also studied. This research provides a basic data for the investigation of macrofauna in the Bohai Sea, and used the method of functional group in the Bohai Sea in the first time. The main results of this research are as follows:(1) A total of 299 species were collected in the Bohai Sea in the four cruises during 2013-2014. Annelida, which accounts for the highest percentage of species (41%), had 121 species; Arthropoda was the secondary groups in this study, which accounted for 31% of the total species; Mollusca had 42 species, which accounted for 14%; Echinodermat had 20 species, which accounted for 7%; Coelenterata had 9 species, which accounted for 9%; the other groups were found 13 species. Annelida was the most dominant group of macrobenthos in the Bohai Sea.(2) The indices of relative importance was used for defining dominant species, which included Annelida (12 species), Arthropoda (5 species), Echinodermat (4 species), Mollusca (2 species) and the other groups (4 species). Some representative species includes Sigambru hanaokai, Sternaspis scutata, Nephtys oligobranchia, Protankyra bidentata, Moerella iridescens, Nemertineu.(3) The macrobenthos species belonged to 5 types of functional group, which included Carnivorous groups (C), Phytophagous groups (Ph), Planktobagous group (PI), Omnivorous groups (O), Detritivorous group (D).Species numbers of in each functional group with the order from high to low were D>C>Pl>O>Ph; in terms of abundance. it was D>C>Pl>O>Ph. The most significant groups was Detritivorous group follow by Carnivorous groups. The most rare group was Phytophagous groups.(4) Macrobenthic communitis structure were divided into three groups in 1307 cruises, two groups in 1311 cruises, four groups in 1405 cruises and four groups in 1411 cruises.Most of the Dominant species were polychates and crustaceans. Community structure of the macrobenthos in Bohai Sea changed compared with the historical data, with a trend of "miniaturization".(5) Four cruises were used as a support during 2013-2014 for researching the bio-diversity of macrobenthos in the Bohai Sea. In terms of species number and Shannon-wiener index and richness index, those in spring cruise were higher in 2013. Opposite distribution phenomenon were found in 2014. The causes of this patterns included the dominant environmental factors, such as water depth and below water salinity, and the difference of macrobenthos composition. The Shannon-wiener index ranged from 3.35 to 5.64; richness index ranged from 3.45-10.74; Pielou index ranged from 0.70 to 0.92 in the four cruises.(6) Using BIOENV, analyses the best environmental factors combination to affect each functional group were obtained. The main results of this research are as follows:the best environmental factors combination of Carnivorous groups were water depth, bottom water salinity(BWS), Sediment water content(%), Ph-a(mg/kg); Detritivorous group were BWS and the content of Organic matter; Omnivorous groups were water depth, bottom water temperature(BWT). BWS. Chl-a(mg/kg); Planktobagous group were water depth, BWS.(7) The method of Macrobenthos bio-diversity and functional group diversity comprehensively were used for analyzing the biodiversity of macrobenthos in the Bohai Sea. The conclusion obtained from the previous study was consistent which indicated biodiversity of macrobenthos tended to be stable and did not emerging signs of disturbance. The functional group of research methods, however, could conquer the difficulties due to difference of sampling stations and reduce effectively the interference of results analyzing which generated by some opportunities species. The method of functional group, in this paper, is superior to the traditional method of species diversity.