Spatial And Temporal Variations Of Planktonic Dinoflagellates And Relationships To Environmental Conditions In Jiaozhou Bay, Norethern China

The community and population dynamics of planktonic dinoflagellates were investigated in five differentstations of Jiaozhou Bay, northern China from June2007to May2008, to reveal the relationships between thepatterns of planktonic dinoflagellates and the environmental factors. A total of60samplings were carried outmonthly, and1000ml seawater samples fixed with acid Lugol’s lodine solution were sampled, analyzed andpresented as well as nine of main environmental and biological factors during the annual investigation.As a result of the survey, the temporal analysis reveals that (i)23dinoflagellates, of which the dominantspecies consist of Alexandrium tamarense, Dinophysis acuminate, Gonyaulax verior, Prorocentrum micans,Prorocentrum minimum, Protoperidinium pellucidum, Scrippsiella trochoidea, Prorocentrum lima, Akashiwosanguinea and Ceratium tripos were identified and mostly belonged to Gonyaulacida and Prorocentrida whichalso greatly contributed to the total abundance;(ii) dinoflagellates exhibited a classic bimodal pattern ofseasonal richness in August and April, abundance with maxima in August and March;(iii) The speciesevenness and diversity leveled off at a relatively stable and high level in summer and autumn, whereas thespecies richness had a bimodal pattern in August and April;(iv) multivariate biota-environment analysisshowed the dinoflagellates community structure matched the combination of salinity and temperature best;(v)the species number and richness were significantly positively correlated with temperature and NO3-N andNO2-N, but negatively correlated with salinity, and the abundance were significantly negatively correlated withsalinity (p <0.01);(vi) D. acuminate, G. verior, P. micans, S. trochoidea, P. lima, A. sanguinea and C. triposwere generally significantly positively correlated with temperature and nutriments, and significantly negativelycorrelated with salinity (p <0.01).The analysis of spatial patterns of planktonic dinoflagellates communities reveals that (i) environmentalfactors at five different stations of Jiaozhou Bay were spatially different;(ii) only nine spicies of total23dinoflagellates were distributed in all the five satations. And there were seven taxa at90%level of thecumulative contribution percentage to the50%similarity level among the dinoflagellates communities at the five stations;(iii) among the five sampling stations, there were highest cumulative abundance and speciesnumber in the station A, lowest abundance in the station C, and least species number in the station E. Therelative cumulative compositions of taxonomy at the five stations were similar, and mostly belonged toGonyaulacida, Peridiniida and Prorocentrida, whereas the relative cumulative compositions of abundancewere different, which Peridiniida was dominant in th station A, Gonyaulacida in the station B, C and E, andGonyaulacida and Prorocentrida in the station D;(iv) the species diversity and richness were at a relativelystable level in the station B, C and E, but the highest level in the station A and the lowest level in the station E;and the species evenness in the station B, C and E was relatively stable and high,but low in station Aand E;(v) spatial patterns of planktonic dinoflagellates communities was considerably related to the assembleof salinty, NH3-N, and NO2-N; the spatial distributions of A. tamarense, S. trochoidea, C. furca, P.conicum and P. pellucidum were significantly correlated with some environment factors; the spatialvariations of structural parameters including the species number, richness, evenness and diversity as well asthe abundance of dinoflagellates communities were considerably correlated with PH and nutrients.