Short-term tidal and diel variations of autumn fish assemblage in a Zostera marina bed were investigated using 3 h interval samplings for 24 h in both spring and neap tide using a small beam trawl.A total of 1 346 fis...Short-term tidal and diel variations of autumn fish assemblage in a Zostera marina bed were investigated using 3 h interval samplings for 24 h in both spring and neap tide using a small beam trawl.A total of 1 346 fishes belonging to 19 species were collected at spring tide,whereas 1 115 fishes belonging to 17 species were at neap tide.The common fish species were Nuchequula nuchalis,Acanthogobius flavimanus,Takifugu niphobles,Acentrogobius pflaumii,and Pholis nebulosa with the former three species dominating at spring tide,while the latter two species being abundant at neap tide.Diel variation in abundance was significant with higher abundance at night than day,but there were no significant differences between spring and neap tides,and between ebb and flood tides（three-way ANOVAs）.Diel variation in the abundance of fishes may be influenced by tidal range and cycle,and day-night differences of food availability and behaviors of fishes indirectly.Non-metric multidimensional scaling（n MDS） ordination and analysis of similarity（ANOSIM） results revealed significant differences in species compositions both between day and night,and between spring and neap tide.Eelgrass beds are highly productive marine ecosystem,and thus,our results will contribute to conservation of seagrass ecosystem in the study area.展开更多
The environmental regulation of plcoplankton distribution in the northern South China Sea was examined In winter and summer of 2004. The average abundance of Synechococcus, Prochlorococcus, and heterotrophlc bacteria ...The environmental regulation of plcoplankton distribution in the northern South China Sea was examined In winter and summer of 2004. The average abundance of Synechococcus, Prochlorococcus, and heterotrophlc bacteria was lower In winter （30, 21, and 780×10^3 cells/cm^3, respectively） than In summer （53, 85, and 1 090×10^3 cells/cm^3, respectively）, but the seasonal pattern was opposite for plcoeukaryotlc phytoplankton （4 500 and 3 200 cells/cm^3 In winter and summer, respectively）. Synechococcus, picoeukaryotes, and bacteria were most abundant in the nutrient-rich coastal zone and continental shelf, but Prochlorococcus was most abundant In the continental slope and open ocean. The vertical distribution of each photosynthetic group and heterotrophlc bacteria changed between the two seasons. Synechococcus populations with apparently different phycoerythrobilin content occurred at many stations In the summer. In addition, two different populations of Prochlorococcus were found： （i） small, weakly fluorescing cells in the surface layer; and （ii） larger, strongly fluorescent cells In the deep layer. The distribution pattern of photosynthetic plcoplankton and heterotrophlc bacteria depends on environmental effects and their ecophyslologlcal differences. The distribution of Synechococcus appeared to be related to nutrient availability, whereas the distribution of Prochlorococcus appeared to be limited by temperature. Synechococcus was the only plcophytoplankton with a consistent strong relationship with bacteria.展开更多
文摘Short-term tidal and diel variations of autumn fish assemblage in a Zostera marina bed were investigated using 3 h interval samplings for 24 h in both spring and neap tide using a small beam trawl.A total of 1 346 fishes belonging to 19 species were collected at spring tide,whereas 1 115 fishes belonging to 17 species were at neap tide.The common fish species were Nuchequula nuchalis,Acanthogobius flavimanus,Takifugu niphobles,Acentrogobius pflaumii,and Pholis nebulosa with the former three species dominating at spring tide,while the latter two species being abundant at neap tide.Diel variation in abundance was significant with higher abundance at night than day,but there were no significant differences between spring and neap tides,and between ebb and flood tides（three-way ANOVAs）.Diel variation in the abundance of fishes may be influenced by tidal range and cycle,and day-night differences of food availability and behaviors of fishes indirectly.Non-metric multidimensional scaling（n MDS） ordination and analysis of similarity（ANOSIM） results revealed significant differences in species compositions both between day and night,and between spring and neap tide.Eelgrass beds are highly productive marine ecosystem,and thus,our results will contribute to conservation of seagrass ecosystem in the study area.
基金Supported by the National Natural Science Foundation of China （90211021, 40506032）.Acknowledgements The authors sincerely thank Dr WKW Li （Biological 0ceanography Section, Bedford Institute of 0ceanography, Department of Fisheries and 0ceans, Dartmouth, Nova Scotia, Canada） for helpful advice on the paper and for sharing hydrological and chemical data from synchronous observations by Xiamen University and the South China Sea Branch, S0A. The authors also thank Dr Xin Peng in our team for help with sample preservation.
文摘The environmental regulation of plcoplankton distribution in the northern South China Sea was examined In winter and summer of 2004. The average abundance of Synechococcus, Prochlorococcus, and heterotrophlc bacteria was lower In winter （30, 21, and 780×10^3 cells/cm^3, respectively） than In summer （53, 85, and 1 090×10^3 cells/cm^3, respectively）, but the seasonal pattern was opposite for plcoeukaryotlc phytoplankton （4 500 and 3 200 cells/cm^3 In winter and summer, respectively）. Synechococcus, picoeukaryotes, and bacteria were most abundant in the nutrient-rich coastal zone and continental shelf, but Prochlorococcus was most abundant In the continental slope and open ocean. The vertical distribution of each photosynthetic group and heterotrophlc bacteria changed between the two seasons. Synechococcus populations with apparently different phycoerythrobilin content occurred at many stations In the summer. In addition, two different populations of Prochlorococcus were found： （i） small, weakly fluorescing cells in the surface layer; and （ii） larger, strongly fluorescent cells In the deep layer. The distribution pattern of photosynthetic plcoplankton and heterotrophlc bacteria depends on environmental effects and their ecophyslologlcal differences. The distribution of Synechococcus appeared to be related to nutrient availability, whereas the distribution of Prochlorococcus appeared to be limited by temperature. Synechococcus was the only plcophytoplankton with a consistent strong relationship with bacteria.
