Taxonomy and ecology of alien Corbicula species - II Biological characteristics of clams and their impacts on ecosystems

Abstract

　Invasive alien species of the genus Corbicula (Bivalvia), originally from Asia, were introduced and spread over North and South America, Europe, and Japan during the 20th century. Dense populations established in the introduced areas have resulted in negative impacts on aquatic ecosystems and local economies. To raise public awareness about this issue, I have written two review papers on the alien Corbicula species: the first summarizes previously published data on taxonomy, native ranges, introduction routes, and dispersion pathways; the present (second) paper summarizes data on biological characteristics, including mode of reproduction, feeding behaviour, physiological tolerance to abiotic changes, impacts of established Corbicula populations on ecosystems and economies, and the response of native ecosystems to the introduced Corbicula species. Future measures and research tasks to resolve the problems associated with Corbicula are also noted. The successful invasive behaviour of Corbicula species can be explained by their reproduction/life-history traits (hermaphroditism, unreduced biflagellate sperm, androgenesis, ovoviviparity, r-strategy with rapid individual growth, early maturity, high fecundity, and high dispersal ability), plasticity in feeding behaviours (suspension- and deposit-feeding), and high filtration rates rather than by their physiological tolerance to abiotic changes (salinity, temperature, oxygen, etc.).