Biodeposition, respiration, and excretion rates of an introduced clam Mercenaria mercenaria in ponds with implications for potential competition with the native clam Meretrix meretrix in Shuangtaizi estuary, China

This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition, respiration, and excretion rates of 34. mercenaria were determined seasonally using a sediment trap and a closed respirator in field. The biodeposition rates ofM. mercenaria were 0.06-0.37 g/ （ind.·d）, and the respiration rates were 0.31-14.66 mg/（ind.·d）. The ammonia and phosphate excretion rates were 0.18-36.70 and 1.44-14.87 μg/（ind.·d）, respectively. The hard clam M. mercenaria may discharge dry deposits up to 2.1 × 10^5 t, contribute 18.3 t ammonia and 9.0 t phosphate to culture ponds, and consume 7.9×10^3 t O2 from ponds annually. It suggested that the hard clam M. mercenaria might play an important role in pelagic-benthic coupling in pond ecosystem through biodeposition and excretion. A comparison of the key physiological parameters of the introduced clam M. mercenaria and the native clam Meretrix meretrix suggested that M. mercenaria had a niche similar to that of Meretrix meretrix in Shuangtaizi estuary and might have a potential competition with Meretrix meretrix for habitat and food ifM. mercenaria species escaped from the culture pond or artificially released in estuarine ecosystem.

Cooperation strategies when leading firms compete with small and medium-sized enterprises in a potentially competitive market

Efficient cooperation,which has become common under rising economic globalization,is leading to new opportunities and challenges for enterprises choosing long-term competition strategies.Sharing resources with competitors is believed to weaken a firm's competitive edge.However,a potentially competitive market may change a firm's incentive to share resources strategically with rivals.Consequently,this study investigates two possible cooperation models between leading enterprises and small and medium-sized enterprises(SMEs)to examine the impact of sharing resources on a firm's strategy.This analysis shows that cooperation strategies benefit both the leading firm and the SME under certain conditions.Furthermore,this study demonstrates that the wholesale cooperation strategy is always more detrimental to the environment than the license cooperation strategy.Interestingly,although cooperation can help SMEs develop sustainably in most cases,industries with high resource costs may experience a situation in which SMEs benefit from competition,thus resisting cooperation and harming the leading enterprise.This study highlights the role of a potentially competitive market and provides managerial insights for stakeholders.

U.K. Needs Clear Choice on China Relations

CHINA and Britain have potentially one of the world’s most fruitful international economic relationships.Not only do they account for 16 percent of world GDP,but their two economies are mutually complementary rather than competitive.China is now the world’s largest industrial producer,

Structure of National Science and Technology Competitiveness: A Methodological and Empirical Study

This paper clearly defines the concepts of the national competitiveness,the national S&T competitiveness,and the national S&T competitiveness structure.It develops an evaluation framework with three dimensions:the national S&T competitive potential,the national S&T competitive strength and the national S&T competitive effectiveness.This paper proposes a structure analysis method and depicts the national S&T competitiveness structure of 35 countries in an empirical research.Apart from the definitions and the structure analysis method,this paper mainly draws the following conclusions:(1)In the one-dimensional national S&T competitiveness structure,the top 5 countries were all developed countries in 2015,while the developing countries generally performed better than developed countries considering the average annual growth rate of the national S&T competitiveness index.The 35 countries are clustered into 4 categories using the two-dimensional structure analysis method.For example,based on the ranking of the national S&T competitive strength index and the national S&T competitive effectiveness index of the 35 countries in 2015,the 35 countries are clustered into four categories:high-strength and higheffectiveness,low-strength and high-effectiveness,low-strength and low-effectiveness,and high-strength and low-effectiveness.(2)To a large extent,there is a significant correlation between the national S&T competitiveness index score and the GDP per capita value.And to a certain extent,there is some correlation between the national S&T competitiveness index score and the GDP value.Moreover,under the background of strength and effectiveness combination,or under the background of strength and potential combination,the national S&T competitiveness structure and GDP or GDP per capita show significant relationship.