A year-long survey of some physical parameters （water temperature, dissolved oxygen, pH, turbidity）, chemical parameters （Biological Oxygen Demand ＂BOD＂, Chemical Oxygen Demand ＂COD＂, nitrate, ammonia, orthopho...A year-long survey of some physical parameters （water temperature, dissolved oxygen, pH, turbidity）, chemical parameters （Biological Oxygen Demand ＂BOD＂, Chemical Oxygen Demand ＂COD＂, nitrate, ammonia, orthophosphate） and some biological （zooplankton） and microbiological （total bacteria, indicator bacteria, pathogenic bacteria） components in Domat AI-Gandal Lake was conducted. Water samples were collected seasonally from spring 2004 to winter 2005. Four locations on the Lake were sampled in order to evaluate the condition of the Lake. To investigate the possible effect of zooplankton in controlling the presence of faecal indicator bacteria, a 24 hour experiment was carried out to examine this hypothesis as well as the grazing pressure of zooplankton on the bacterial community of the Lake. The results showed that variations in season temperature affected the zooplankton and density of bacteria in the Lake. Zooplankton was composed by Protozoa 75%, Rotifera 20.6%, Cladocera 3% and Copepoda 2%. The reduction rates for the tested faecal pollution indicators in presence of zooplankton predators were remarkable （up to 99%）. In conclusion zooplankton, especially protozoa, was found to play an important role as biological control against bacterial indicators of faecal pollution.展开更多
Two kinds of animal remains have been found on Neolithic China sites: domesticated and wild. The former include those of pigs, dogs, chickens, cattle and sheep; the latter belong to the sika deer, Bavid’s deer, river...Two kinds of animal remains have been found on Neolithic China sites: domesticated and wild. The former include those of pigs, dogs, chickens, cattle and sheep; the latter belong to the sika deer, Bavid’s deer, river deer, muntjac, red deer, roe deer, tiger, wolf, racoon dog, bear, badger, monkey, rabbit, bamboo rat, various kinds of fish and so on. Through qualitative and quantitative analyses of bones from Neolithic sites the author learns that the remains of domesticated and wild animals in different regions and sites vary in proportion, which shows the existence of different meat--acquiring patterns at that time. Northeast China, Inner Mongolia, the upper and middle Huanghe River valley, the Huanghe-Huaihe region, the Changjiang Three Gorges area, the Changjiang delta and South China all have their own characteristics, which can be summed up and classified into three patterns: dependent, elementary animal domestication, and advanced animal domestication. When the three patterns are lined up in the above order, a model of meat-acquiring in Neolithic China is formed, which demonstrates the basic developmental process of meatacquiring in Neolithic China. The author believes that the sequential changes of meat-acquiring patterns from completely depending on hunting via supply partly by elementary animal domestication to relying mainly on domesticated animals always happened and developed under the restriction by surrounding natural resources. Therefore, this process can be summed up in a theory of passive development.展开更多
Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present...Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium cur- vispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a disper- sal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range展开更多
文摘A year-long survey of some physical parameters （water temperature, dissolved oxygen, pH, turbidity）, chemical parameters （Biological Oxygen Demand ＂BOD＂, Chemical Oxygen Demand ＂COD＂, nitrate, ammonia, orthophosphate） and some biological （zooplankton） and microbiological （total bacteria, indicator bacteria, pathogenic bacteria） components in Domat AI-Gandal Lake was conducted. Water samples were collected seasonally from spring 2004 to winter 2005. Four locations on the Lake were sampled in order to evaluate the condition of the Lake. To investigate the possible effect of zooplankton in controlling the presence of faecal indicator bacteria, a 24 hour experiment was carried out to examine this hypothesis as well as the grazing pressure of zooplankton on the bacterial community of the Lake. The results showed that variations in season temperature affected the zooplankton and density of bacteria in the Lake. Zooplankton was composed by Protozoa 75%, Rotifera 20.6%, Cladocera 3% and Copepoda 2%. The reduction rates for the tested faecal pollution indicators in presence of zooplankton predators were remarkable （up to 99%）. In conclusion zooplankton, especially protozoa, was found to play an important role as biological control against bacterial indicators of faecal pollution.
文摘Two kinds of animal remains have been found on Neolithic China sites: domesticated and wild. The former include those of pigs, dogs, chickens, cattle and sheep; the latter belong to the sika deer, Bavid’s deer, river deer, muntjac, red deer, roe deer, tiger, wolf, racoon dog, bear, badger, monkey, rabbit, bamboo rat, various kinds of fish and so on. Through qualitative and quantitative analyses of bones from Neolithic sites the author learns that the remains of domesticated and wild animals in different regions and sites vary in proportion, which shows the existence of different meat--acquiring patterns at that time. Northeast China, Inner Mongolia, the upper and middle Huanghe River valley, the Huanghe-Huaihe region, the Changjiang Three Gorges area, the Changjiang delta and South China all have their own characteristics, which can be summed up and classified into three patterns: dependent, elementary animal domestication, and advanced animal domestication. When the three patterns are lined up in the above order, a model of meat-acquiring in Neolithic China is formed, which demonstrates the basic developmental process of meatacquiring in Neolithic China. The author believes that the sequential changes of meat-acquiring patterns from completely depending on hunting via supply partly by elementary animal domestication to relying mainly on domesticated animals always happened and developed under the restriction by surrounding natural resources. Therefore, this process can be summed up in a theory of passive development.
文摘Drifting can be an effective way for aquatic organisms to disperse and colonise new areas. Increasing connectivity between European large rivers facilitates invasion by drifting aquatic macroinvertebrates. The present study shows that high abundances of invasive species drift in the headstream of the river Rhine. Dikerogammarus villosus and Chelicorophium cur- vispinum represented up to 90% of the total of drifting macroinvertebrates. Drift activity shows seasonal and diel patterns. Most species started drifting in spring and were most abundant in the water column during the summer period. Drift activity was very low during the winter period. Diel patterns were apparent; most species, including D. villosus, drifted during the night. Drifting macroinvertebrates colonised stony substrate directly from the water column. D. villosus generally colonised the substrate at night, while higher numbers of C. curvispinum colonised the substrate during the day. It is very likely that drifting functions as a disper- sal mechanism for crustacean invaders. Once waterways are connected, these species are no longer necessarily dependent on dispersal vectors other than drift for extending their distribution range
