Effects of upper-limit water temperatures on the dispersal of the Asian clam Corbicula fluminea.
Temperature is a determinant environmental variable in metabolic rates of organisms ultimately influencing important physiological and behavioural features. Stressful conditions such as increasing temperature, particularly within high ranges occurring in the summer, have been suggested to induce flotation behaviour in Corbicula fluminea which may be important in dispersal of this invasive species. However, there has been no experimental evidence supporting this hypothesis. It was already proven that C. fluminea drift is supported by a mucilaginous drogue line produced by mucocytes present in the ctenidia. Detailed microscopic examination of changes in these cells and quantification of clam flotation following one, two and three weeks of exposure to 22, 25 and 30°C was carried out so that the effects of increasing water temperatures in dispersal patterns could be discussed. Results show that changes in temperature triggered an acceleration of the mucocytes production and stimulated flotation behaviour, especially following one week of exposure. Dilution of these effects occurred following longer exposure periods. It is possible that these bivalves perceive changing temperature as a stress and respond accordingly in the short-term, and then acclimate to the new environmental conditions. The response patterns suggest that increasing water temperatures could stimulate C. fluminea population expansion.
Department of Biology, University of Aveiro and CESAM (Centre for Environmental and Marine Studies), Aveiro, Portugal.
Inês Correia
IC
Rosa
Joana Luísa
JL
Pereira
Raquel
R
Costa
Fernando
F
Gonçalves
Robert
R
Prezant
D000818:Animals; D049874:Corbicula / Q000502:physiology*; D004784:Environmental Monitoring; D013696:Temperature; D014867:Water
D014867:Water