Studies On The Mesozooplankton And Microzooplankton Community In The Yellow River Estuary And Its Adjacent Area In Summer And Autumn

Zooplankton community structure and its influencing factors were studied by means of multi-variable and bio-environmental analysis based on the samples collected in the Yellow River estuary and its adjacent area during two survey cruises conducted separately in summer (Jul. 2009) and autumn (Sep.2010) The research can provide important fundamental information for the long-term monitoring of zooplankton ecology in the study area.A total of 60 zooplankton taxa and 27 pelagic larvae were identified during two surveys, and they belonge to Protozoa, Cnidaria, Ctenophora, Chordata, Arthropoda and Chaetognatha. Crustacea and Cnidaria were the most abundant two components of the zooplankton. The species number of pelagic crustacean represented above 50% of total species richness and copepods were the most dominant crustacean in the study area.During summer, the abundance of zooplankton is from 1158.3 -131223.2 ind/m3, the mean abundance value of zooplankton is 50839.3 ind/m3. The abundance in the middle and northern survey area is higher than that in inshore of Yellow River Estuary and in Laizhou Bay. In autumn, the abundance of zooplankton is from 2300.1-266232.0 ind/m3, the main abundance of zooplankton is 37074.3 ind/m3 .The abundance in southern and northern area is higher than that in the middle area.In summer survey, there are 9 dominant species in the survey area, they are Paracalanus crassirostris, Paracalaus parvus, Acartia bifilosa, Oithona brevicornis, Oithona similis, Corycaeus affinis, Oikopleura dioica, Nauplius larvae and Brivial larvae, Paracalanus parvus is the most dominant specie in summer. In autumn survey, there are 8 dominant species in the survey area, they are Paracalanus crassirostris, Paracalanus parvus, Centropages dorsispinatus, Oikopleura dioica, Nauplius larvae, Gastropod post larve, Brival larvae and Noctiluca scintillans, Noctiluca scintillans is the most dominant specie in autumn, and its abundance is more than 61.0% of mean abundance of all meso- and micro-zooplankton.In summer, based on the abundance of each species in each station, 3 groups are distinguished by the CLUSTER analysis using PRIMER 6.1 software. Group GS1 is located at the inshore of the north shore of the Yellow River estuary, the dominant species are Paracalanus crassirostris, Paracalanus pavus, Acartia bifilosa, Oithona brevicornis, Oithona similis, Oikopleura dioica, Brivial larvae and Tintinnopsis spp; Group GS2 is located out of the Yellow River estuary, the dominant species contents Paracalanus crassirostris, Paracalanus parvus, Acartia bifilosa, Oithona brevicornis, Oithona similis, Corycaeus affinis, Oikopleura dioica, Nauplius larvae, Gastropod post larvae and Brivial larvae; Group GS3 is located at the inshore of the south shore of the Yellow River estuary, the dominant species in this group are Paracalanus crassirostris, Paracalanus parvus, Acartia bifilosa, Oithona brevicornis and Brivial larvae, the GS3 contents 2 stations is exist only in the summer survey but not in autumn. In autumn, there are 4 groups in the survey area. Group GA1 is at the same location as GS1, the dominant species in this group are Noctiluca scintillans, Favella panamensis, Paracalanus parvus, Centropages dorsispinatus, Sagitta crassa, Oikopleura dioica, Nauplius larvae, Gastropod post lava and Brivial larvae; The summer group GS2 is distinguished into two groups GA3 and GA2 in autumn, GA2 is adjacent to the Yellow River estuary, the dominant species are Noctiluca scintillans, Paracalanus parvus, Centropages dorsispinatus, Oithona brevicornis, Sagitta crassa, Nauplius larvae and Brivial larvae; GA3 is at the periphery of GA2, it dominant species contents Noctiluca scintillans, Paracalanus crassirostris, Paracalanus parvus, Centropages dorsispinatus, Oithona similis, Oikopleura dioica and Brivial larvae; Group GA4 is located in the Laizhou Bay, the dominant species are Nocatiluca scientillans, Paracalanus crassirostris, Centropages dorsispinatus, Oithona brevicornis and Nauplius larvae. The common dominant species in all of the 4 groups are Noctiluca scientilla and Centropages dorsispinatus.In summer, the mean Shannon-Weaner Diversity and Pielou′s evenness are 2.72 and 0.55, which are higher in the ground than in the center, the mean Margalef species richness is 2.97, which is higher in the inshore than in the offshore. In autumn, the mean Shannon-Weaner Diversity and Pielou′s evenness are 2.49 and 0.51, which are higher at the Yellow River estuary and the northeast of the survey area, the mean Margalef species richness is 2.80, which is higher at the southern and the northern east area.