Community Structure Of Plankton In Haizhou Bay And Adjacent Waters And Their Relationships With Environmental Factors

Based on the data collected from four seasonal surveys in 2011 in Haizhou Bay and adjacent waters, community structures of phytoplankton and zooplankton were studied and their relationships with environmental factors were evaluated by canonical correlation analysis (CCA), aiming at evaluating the ecological environment accurately, and providing a scientific basis to protect and exploit the fishery resources reasonably of haizhou bay and adjacent waters. Main research results were as follows:A total of 113 phytoplankton species belonging to 3 phyla and 44 genera were collected, among which Bacillariophyta species were the most abundant species, which included 39 genera and 99 species, accounting for 87.6 percent of total taxa, followed by Pyrrophyta, which included 4 genera and 13 species, accounting for 11.5 percent of total taxa. And the least abundant species were Chrysophyta species, which had only 1 species belonging to 1 genus. Among these dominant species, Coscinodiscus and Chaetoceros were the dominant groups in Bacillariophyta, while Ceratium was the dominant group in Dinophyta. And the dominant species were Meuniera membranacea, Coscinodiscus subtilis var. subtilis, Eucampia zodiacus and Bacillaria paxillifera. There were obvious seasonal variations in the species composition and predominant species. The abundances of phytoplankton in all the stations ranged from 0.0829×105 cells·m-3 to 108.48×105 cells·m-3 in Haizhou Bay. The average annual density of phytoplankton was 10.71×105 cells·m-3, being the highest in autumn (29.08×105 cells·m-3) and the lowest in summer (1.69×105 cells·m-3). The Shannon index, Pielou index and Margalef index of the phytoplankton community were higher in summer and autumn than in winter and spring. Canonical correlation analysis (CCA) suggested that the main factors affecting the phytoplankton community were sea surface temperature (SST), followed by nutrition (NO3--N, PO43--P, SiO32--Si) and dissolved oxygen (DO). The abundances and distribution of some dominant species were closely related with these main factors.A total of 86 zooplankton species including 24 species of pelagic larvae, which belonging to 7 phyla and 15 genera were collected. There were 1 species of Protozoa,1 species of Mollusca.20 species of Coelenterata.2 species of Ctenophora,2 species of Chaetognatha,33 species of Arthropoda and 2 species of Urochordata among these species. The species numbers of zooplankton were highest in summer, followed by winter and autumn, lowest in spring, and the numbers were 57,50,48 and 43 respectively, which presented the variety characteristics of that the species numbers were higher in summer and winter than in spring and autumn. The average annual density of zooplankton was 826 inds·m-3 in Haizhou Bay, being the highest in spring (2126 inds·m-3) and followed by summer (554 inds·m-3) and winter (145 inds·m-3), while the lowest in autumn (72 inds·m-3). The average annual biomass of zooplankton was 194.69 mg·m-3 in Haizhou Bay. being the highest in spring (451.65 mg·m-3) and followed by summer (162.88 mg·m-3)and autumn (59.91 mg·m-3), while the lowest in winter 34.84 mg·m-3). The absolute dominant species in spring and winter was Noctiluca scientillans Kofoid et Swezy, there were an obvious dominance in part of pelagic larvae such as Echinopluteus larva, Brachyura zoea larva and Macrura larva in summer and autumn, while the dominant species throughout the year were Calanus sinicus Brodsky and Sagitta crassa Tokioka. The Shannon index, Pielou index and Margalef index of the zooplankton community were consistent with the seasonal trends of species number, which was the highest in summer, followed by winter and autumn, lowest in spring. Canonical correlation analysis (CCA) suggested that the main factors affecting the zooplankton community were sea surface temperature (SST), followed by Chlorophyll a (Chl-a) and nutrition (NO3--N, SiO32--Si) and dissolved oxygen (DO). The abundances and distribution of some dominant species were closely related with these main factors.