The Biomass Size Spectrum And Its Application In The Southern Yellow Sea

The biomass size spectrum is the distribution pattern of zooplankton size in themarine ecosystem, which was used to analysis the trophic structure of zooplanktoncommunity widely in recent years. In this paper，the data of zooplankton and fish thatcollected from southern Yellow Sea by R/V “Beidou” in August,2007; October,2009;January,2010and May,2010(33.50°N～37.00°N，121.5°E～124.5°E) were used toanalysis the trophic structure of zooplankton community dependent on the biomasssize spectra theory, and discussed the relationships between the parameters ofzooplankton biomass size spectrum and the catch of little yellow croaker and anchovybased on GAMs and GLMs in the southern Yellow Sea. The results will be helpful inthe studies of food trophodynamics and output on a sustainable basis of the YellowSea ecosystem. The following is the main results:1. The Sheldon-type biomass size spectra of the total zooplankton in the fourseasons were all continuous, and there were four crests. The size class rangewas-2.1to15.7. The biomass of spectra was on the rise, along with the risingof size. There were some differences among the Sheldon-type biomass sizespectra of zooplankton in the four seasons.2. The normalized biomass size spectra of the four seasons can be fitted into a line,which the slope was-0.75, the intercept was18.7,and r20.74. The wholezooplankton in each season was divided into four groups: S, M, L, XL based onthe domes of the biomass size spectra. And the biomass size spectra of M and Lcan be fitted into a straight line significantly. The seasonal change of the slopesof biomass size spectra in the four seasons was spring<autumn and winter<summer; the intercepts autumn<winter<summer<spring.3. The size diversity index in summer was the biggest one, and it was0.00597, while it was the smallest in winter. The diversity in spring was similar to inautumn. There were significant differences among the diversities in the fourseasons by ANOVA (F=13.15, p<0.01). And the spatial distribution in theseasons also was different.4. The change of trophic levels was in accordance with the slopes. In spring, thetrophic level (TL) within the whole zooplankton community was the smallest,but it was the biggest in M group among the four seasons, the TL of Lzooplankton was the second largest. The TL within the whole zooplanktoncommunity was bigger in summer than that in the other seasons, and it was4.0.while the TL of M zooplankton was the smallest. The TLs in autumn and winterwere both3.8. While the TLs of L zooplankton in autumn was smaller than thatin the other seasons, and in winter, it was the biggest one.5. The results of GAMs of little yellow croaker showed that the slope andintercept on the influence of the catch of little yellow croaker was nonlinear.6. The model between the parameters of zooplankton biomass size spectra and thecatch of anchovy was linear, the formula was log2Fa=-4.77*slope-0.67*intercept+11.01, where Fa is the catch of anchovy, slope, intercept is thezooplankton biomass size spectra’s slope and intercept, respectively. The modelshowed that the larger the slope and intercept became, the fewer the catch ofanchovy.