To study the relationship between zooplankton community structure and environmental factors and water quality in the Harbin Section of the Songhua River,investigations were carried out in June,August,and October 2011....To study the relationship between zooplankton community structure and environmental factors and water quality in the Harbin Section of the Songhua River,investigations were carried out in June,August,and October 2011.Canonical correspondence analysis(CCA) and saprobic indices were used to process and analyze the data.Seasonal variability was identified as a significant source of variation,which explains the fluctuation in zooplankton density.In autumn,the dry season,water residence time increased and zooplankton biomass and abundance accumulated in the slow flowing waters.Zooplankton abundance increased when food conditions improved.Therefore,the total zooplankton abundance in autumn is much higher than that in spring and summer.According to the saprobic indices,all the sample sites had mesosaprobic water and water quality was worse in autumn.CCA revealed that temperature accounted for most of the spatial variation in the zooplankton community.Moreover,pH,dissolved oxygen saturation,and turbidity were important factors affecting zooplankton community distribution.展开更多
Laizhou Bay provides a critical spawning and nursery habitat for many fishery species,including commercially important species,such as Fenneropenaeus chinensis and Larimichthys polyactis.The bay is severely stressed d...Laizhou Bay provides a critical spawning and nursery habitat for many fishery species,including commercially important species,such as Fenneropenaeus chinensis and Larimichthys polyactis.The bay is severely stressed due to high fishing pressure and environmental changes.Based on the long-term ecosystem surveys in Laizhou Bay during the main spawning period(May) of most fishery species from 1959 to 2008,the responses of the Laizhou Bay fishery ecosystem were analyzed here,including regime shifts in species composition,biomass,species diversity,zooplankton,phytoplankton,and environmental variables.The dominant species of large-size and high economic value(e.g.Trichiurus haumela,L.polyactis) have been replaced by the short-lived,low-trophic-level planktivorous pelagic species(e.g.Setipinna taty,Engraulis japonicus) since the 1980s,and it is probable that the small-sized pelagic fishes have been recently replaced by invertebrates(e.g.Oratosquilla oratoria,Crangon affinis).The biomass of fishery resources declined continuously from 423.6 kg haul?1 h?1 in 1959 to 164.6 kg haul?1 h?1 in 1982,37.7 kg haul?1 h?1 in 1993,and less than 8 kg haul?1 h?1 in 1998-2008.Moreover,the biomass of zooplankton showed an increasing trend during 1959-2006,but showed a slight decline in 2008.The abundance of phytoplankton increased from 1959 through 1982,decreased substantially in 1993,and increased again until 2004.More recently,however,the phytoplankton abundance was very low.The sea surface temperature(SST) and sea bottom temperature(SBT) in May increased by 0.23°C a?1 and 0.16°C a?1,respectively,during 1982-2008.The salinity in May showed large fluctuations and reached its lowest values in 2004 and 2006.The ratio of dissolved inorganic nitrogen(DIN) to dissolved inorganic phosphate(DIP) increased.However,the dissolved silicon(DSi):DIP and DSi:DIN ratios decreased to a low level during 1959-2008.These changes seriously impacted primary production,and cascade effects then changed the structure and function of the fishery ecosystem.Further analysis indicated that multiple stresses caused the alterations in the structure of the Laizhou Bay fishery ecosystem.The top-down effect was identified as the main influence on the fishery species(at the top of the food chain) over the past five decades due to the increasing fishing pressure,whereas the bottom-up effect increased over the past three decades due to the strong variations in the environment.展开更多
基金Supported by the National Natural Science Foundation of China(No.41271106)
文摘To study the relationship between zooplankton community structure and environmental factors and water quality in the Harbin Section of the Songhua River,investigations were carried out in June,August,and October 2011.Canonical correspondence analysis(CCA) and saprobic indices were used to process and analyze the data.Seasonal variability was identified as a significant source of variation,which explains the fluctuation in zooplankton density.In autumn,the dry season,water residence time increased and zooplankton biomass and abundance accumulated in the slow flowing waters.Zooplankton abundance increased when food conditions improved.Therefore,the total zooplankton abundance in autumn is much higher than that in spring and summer.According to the saprobic indices,all the sample sites had mesosaprobic water and water quality was worse in autumn.CCA revealed that temperature accounted for most of the spatial variation in the zooplankton community.Moreover,pH,dissolved oxygen saturation,and turbidity were important factors affecting zooplankton community distribution.
基金supported by Special Fund for Agro-scientific Research in the Public Interest(Grant No.200903005)National Basic Research Program of China(Grant Nos.2011CB409805 and 2010CB951204)Taishan Scholar Program of Shandong Province
文摘Laizhou Bay provides a critical spawning and nursery habitat for many fishery species,including commercially important species,such as Fenneropenaeus chinensis and Larimichthys polyactis.The bay is severely stressed due to high fishing pressure and environmental changes.Based on the long-term ecosystem surveys in Laizhou Bay during the main spawning period(May) of most fishery species from 1959 to 2008,the responses of the Laizhou Bay fishery ecosystem were analyzed here,including regime shifts in species composition,biomass,species diversity,zooplankton,phytoplankton,and environmental variables.The dominant species of large-size and high economic value(e.g.Trichiurus haumela,L.polyactis) have been replaced by the short-lived,low-trophic-level planktivorous pelagic species(e.g.Setipinna taty,Engraulis japonicus) since the 1980s,and it is probable that the small-sized pelagic fishes have been recently replaced by invertebrates(e.g.Oratosquilla oratoria,Crangon affinis).The biomass of fishery resources declined continuously from 423.6 kg haul?1 h?1 in 1959 to 164.6 kg haul?1 h?1 in 1982,37.7 kg haul?1 h?1 in 1993,and less than 8 kg haul?1 h?1 in 1998-2008.Moreover,the biomass of zooplankton showed an increasing trend during 1959-2006,but showed a slight decline in 2008.The abundance of phytoplankton increased from 1959 through 1982,decreased substantially in 1993,and increased again until 2004.More recently,however,the phytoplankton abundance was very low.The sea surface temperature(SST) and sea bottom temperature(SBT) in May increased by 0.23°C a?1 and 0.16°C a?1,respectively,during 1982-2008.The salinity in May showed large fluctuations and reached its lowest values in 2004 and 2006.The ratio of dissolved inorganic nitrogen(DIN) to dissolved inorganic phosphate(DIP) increased.However,the dissolved silicon(DSi):DIP and DSi:DIN ratios decreased to a low level during 1959-2008.These changes seriously impacted primary production,and cascade effects then changed the structure and function of the fishery ecosystem.Further analysis indicated that multiple stresses caused the alterations in the structure of the Laizhou Bay fishery ecosystem.The top-down effect was identified as the main influence on the fishery species(at the top of the food chain) over the past five decades due to the increasing fishing pressure,whereas the bottom-up effect increased over the past three decades due to the strong variations in the environment.
