This study aims to investigate the seasonal variations in copepod community structure and prosome length of dominant species from March 2009 to January 2010 around artificial reefs in Xiaoshi Island, Yellow Sea, Weiha...This study aims to investigate the seasonal variations in copepod community structure and prosome length of dominant species from March 2009 to January 2010 around artificial reefs in Xiaoshi Island, Yellow Sea, Weihai, China. Samples were collected using two types of plankton net （Model I and Model II） for different-sized copepods. The number of taxon was calculated from the data of both the net types, while the copepod abundance was done using the samples from Model II only. Sixteen species of planktonic copepods, including 5 dominant species, were recorded. Results reveal that Oithona similis was the first dominant species from March to June, and was replaced by Paracalanus parvus in September; both dominated the copepod community in January. Acartia hongi was the second dominant species from March to September. Centropages abdominalis was the third dominant species from March to June, and was replaced by O. sirnilis in September and Corycaeus aJfinis in January. C. affinis was the fourth dominant species in September. Population density of the dominant copepods was compared with that of other similar regions. We found that the dominant species were mostly small copepods （〈1 mm） except for adult Centrapages abdominalis. Seasonal variation in prosome length of O. similis, C. abdominalis, and C. affinis, and their copepodites were studied for the first time in China. For P. parvus and A. hongi, seasonal trends in prosome length variation were similar with those in Jiaozhou Bay, Yellow Sea, Qingdao, China, in a similar temperate domain. The results are helpful for future calculation of copepod biomass and production, and for investigation of the relationship between copepods and fish resources.展开更多
Community structure is an important characteristic in real complex network.It is a network consists ofgroups of nodes within which links are dense but among which links are sparse.In this paper, the evolving network i...Community structure is an important characteristic in real complex network.It is a network consists ofgroups of nodes within which links are dense but among which links are sparse.In this paper, the evolving network includenode, link and community growth and we apply the community size preferential attachment and strength preferentialattachment to a growing weighted network model and utilize weight assigning mechanism from BBV model.Theresulting network reflects the intrinsic community structure with generalized power-law distributions of nodes'degreesand strengths.展开更多
The ＂migrant worker shortage＂ which occurred several）pears ago and the recent ＂labor shortage＂ were both caused by an imbalance between the supply and demand of migrant workers. It is a periodical outcome of spon...The ＂migrant worker shortage＂ which occurred several）pears ago and the recent ＂labor shortage＂ were both caused by an imbalance between the supply and demand of migrant workers. It is a periodical outcome of spontaneous adjustment by the migrant labor market. As rural welfare was greatly enhanced in 2009, migrant workers＇ opportunity cost of working outside their hometowns was raised. The connotation of migrant workers＇ ＂market price＂ is changing. The new generation of migrant workers, namely, those born after 1980, are becoming the mainstay of enterprises＇ employment. Being better educated, they have different lifestyles than previous generations. ＂Leisure and entertainment＂ have become part of their opportunity cost and reduced their labor supply. ＂Labor shortage＂ is an endogenous force that helps transform China＇s growth patter, upgrade the industrial structure and promote urbanization. The seasonal ＂return of migrant workers＂ and the ＂labor shortage＂ which appears around China＇s Spring Festival each year have grown into a unique b,t effective collective bargaining mechanism that helps increase migrant workers＇ wages. Facing labor shortages, governments should regulate the labor market pricing and orientate labor-intensive enterprises towards transition, continue to enhance the social security system for migrant workers and those in rural areas, and make an accurate forecast of the population trend and adjust population policies.展开更多
基金Supported by the National Natural Science Foundation of China(No.41106133)the Shandong University Independent Innovation Foundation(No.2011ZRYQ005)the Program of Academy of Marine Research in Weihai(No.000041342080)
文摘This study aims to investigate the seasonal variations in copepod community structure and prosome length of dominant species from March 2009 to January 2010 around artificial reefs in Xiaoshi Island, Yellow Sea, Weihai, China. Samples were collected using two types of plankton net （Model I and Model II） for different-sized copepods. The number of taxon was calculated from the data of both the net types, while the copepod abundance was done using the samples from Model II only. Sixteen species of planktonic copepods, including 5 dominant species, were recorded. Results reveal that Oithona similis was the first dominant species from March to June, and was replaced by Paracalanus parvus in September; both dominated the copepod community in January. Acartia hongi was the second dominant species from March to September. Centropages abdominalis was the third dominant species from March to June, and was replaced by O. sirnilis in September and Corycaeus aJfinis in January. C. affinis was the fourth dominant species in September. Population density of the dominant copepods was compared with that of other similar regions. We found that the dominant species were mostly small copepods （〈1 mm） except for adult Centrapages abdominalis. Seasonal variation in prosome length of O. similis, C. abdominalis, and C. affinis, and their copepodites were studied for the first time in China. For P. parvus and A. hongi, seasonal trends in prosome length variation were similar with those in Jiaozhou Bay, Yellow Sea, Qingdao, China, in a similar temperate domain. The results are helpful for future calculation of copepod biomass and production, and for investigation of the relationship between copepods and fish resources.
基金Supported by the National Nature Science Foundation of China under Grant No.10832006PuJiang Project of Shanghai under Grant No.09PJ1405000+1 种基金Key Disciplines of Shanghai Municipality (S30104)Research Grant of Shanghai University under Grant No.SHUCX092014
文摘Community structure is an important characteristic in real complex network.It is a network consists ofgroups of nodes within which links are dense but among which links are sparse.In this paper, the evolving network includenode, link and community growth and we apply the community size preferential attachment and strength preferentialattachment to a growing weighted network model and utilize weight assigning mechanism from BBV model.Theresulting network reflects the intrinsic community structure with generalized power-law distributions of nodes'degreesand strengths.
文摘The ＂migrant worker shortage＂ which occurred several）pears ago and the recent ＂labor shortage＂ were both caused by an imbalance between the supply and demand of migrant workers. It is a periodical outcome of spontaneous adjustment by the migrant labor market. As rural welfare was greatly enhanced in 2009, migrant workers＇ opportunity cost of working outside their hometowns was raised. The connotation of migrant workers＇ ＂market price＂ is changing. The new generation of migrant workers, namely, those born after 1980, are becoming the mainstay of enterprises＇ employment. Being better educated, they have different lifestyles than previous generations. ＂Leisure and entertainment＂ have become part of their opportunity cost and reduced their labor supply. ＂Labor shortage＂ is an endogenous force that helps transform China＇s growth patter, upgrade the industrial structure and promote urbanization. The seasonal ＂return of migrant workers＂ and the ＂labor shortage＂ which appears around China＇s Spring Festival each year have grown into a unique b,t effective collective bargaining mechanism that helps increase migrant workers＇ wages. Facing labor shortages, governments should regulate the labor market pricing and orientate labor-intensive enterprises towards transition, continue to enhance the social security system for migrant workers and those in rural areas, and make an accurate forecast of the population trend and adjust population policies.
