The Preliminary Study Of Zooplankton Biomass Size Spectrum In The Central And Southern Yellow Sea And Laizhou Bay

There are two parts in this paper. The first, we have researched the sizecomposition and distribution of zooplankton which collected by plankton net in fourseasons that been represent by August2007, October2009, January and May2010from the central north Yellow Sea. The aim was to confirm the size composition ofdifferent functional group of zooplankton in the central north Yellow Sea, constructthe zooplankton biomass spectrum of the four seasons, compare the seasonal varianceand spatial difference of the spectra parameters among the four seasons, and analysethe relationships between them and the environmental factors. The second, we haveestimated the zooplankton biomass and production depend on the above research inthe late spring in the Laizhou Bay, and estimated the potential zooplanktivorous fishbiomass according to theoretical Borgmann model. The following is the main results:1. The central Yellow Sea1) There were60species been identified in the four seasons, contentedcoelenterate9species, ctenophore2species, copepods38species, amphipoda1species, decapods4species, mysid1species, euphausiid2species,chaetognatha3species. Moreover, there was19kinds larval plankton in thefour seasons. The seasonal change of zooplankton species diversity index wassummer> spring> autumn> winter.2) The trend of seasonal change of total abundance was spring> winter>summer> autumn, which was the same with the total biomass. In terms ofquantity, copepods was the highest among the seasons, account for more than98%of the total abundance, and the biomass proportion of copepods was alsothe highest. Paracalanus and Cyclops was the most among the copepods. Thequantity of non-copepod was lower. As far as biomass, copepods was stillhigher than the other, though the proportion significantly decreased （49%⁷3%）, and the main composition was Calanus sinicus, Paracalanus,Cyclops and Acartiidae. The proportion of non-copepods significantlyincreased, and the dominant species underwent a seasonal variance,amphipoda was the most, and then the euphausiid and chaetognatha in spring,euphausiid and chaetognatha in summer, chaetognatha in autumn and winter.3) The size range of zooplankton was-3¹5, the individual C content0.05μg²0mg, and the size distribution was continuous. The size diversity wasthe highest in spring, the lowest in autumn, and that was similar betweensummer and winter.4) The zooplankton that the size class was smaller than4was mainly smallcopepod, that of Calanus sinicus was4⁸. Euphausiid and chaetognatha wasthe main composition which the size was bigger than8.5) The normalized biomass size spectra slopes of the four seasons were-0.673^-0.796, intercepts were7.041¹0.168. The mean of slopes in autumnwas the highest, and winter the lowest, that of intercepts in spring was highest,and lowest in autumn. Relatively, the distribution of zooplankton biomassfluctuated with the size class was large in autumn.6) The correlation analysis showed that there was seasonal difference in thecorrelation between the characteristic parameters of biomass size spectra andenvironmental factors. that the slope of spectrum and size class diversity of thezooplankton performed a significant positive correlation; There was a negativecorrelation between r2and diversity of zooplankton except spring, and wassignificant in autumn. In winter, the slope and intercept of the biomassspectrum and hydrology factor （water temperature and salinity） hadsignificant positive and negative correlation respectively. The parameters ofbiomass size spectra were highly been affected by the surface salinity, thechlorophyll concentration, and been significant correlation in spring.2. Laizhou BayResults showed, in both months, Zooplankton individuals from samples were inthe size range of-3¹0（in logarithmatic carbon unit）, and continuous Sheldon-typebiomass size spectra without gaps were found similarly. But in May, Sheldon-typebiomass size curve was composed of two major domes attributed by small copepodAcartia bifilosa and meso-individuals Calanus sinicus, Sagitta crassa respectively.While in June, it had only one remarkable dome attributed by meso-individuals C. sinicus and S. crassa. Total zooplankton biomass in June was much lower than that inMay as the A. bifilosa declined greatly. Moreover, the production and P/B ofzooplankton were calculated, their mean values were75mg C.m^-2.d^-1,0.20in May and24mg C. m^-2.d^-1,0.16in June. Normalized biomass size spectra were also constructedon a double log plot and fitted closely with a linear regression line with equations y=-0.9629x+14.893（R²=0.60） in May and y=-0.9063x+12.832（R2=0.80） in June.From theoretical biomass-size spectrum model—Borgmann model （1987）, theprediction of observed fish biomass was0.57gC m^-2in size range of14¹6in Mayand0.1gC m^-2in size range of12²5in June.