MEPS 221:135-143 (2001)  -  doi:10.3354/meps221135

Impact of an exotic clam, Corbula gibba, on the commercial scallop Pecten fumatus in Port Phillip Bay, south-east Australia: evidence of resource-restricted growth in a subtidal environment

Sonia G. Talman1,2,*, Michael J. Keough2

1Marine and Freshwater Resources Institute, PO Box 114, Queenscliff, Victoria 3225, Australia
2Department of Zoology, University of Melbourne, Victoria 3010, Australia
*Present address: National Institute of Water and Atmospheric Research, PO Box 11-115, Hamilton, New Zealand. E-mail:

ABSTRACT: Corbula gibba (Olivi, 1792) a small exotic bivalve from the eastern Atlantic and the Mediterranean has been present in Port Phillip Bay, Victoria, Australia, from as early as 1987. C. gibba is widespread, abundant, and possesses characteristics such as fast growth which may confer a competitive advantage over endemic species like the commercial scallop Pecten fumatus Reeve, 1855. Experimental manipulations in the field showed that ambient densities of C. gibba significantly affected the size and growth of juvenile P. fumatus. This effect was greater than the effect of an equivalent number of conspecific scallops. C. gibba did not, however, affect scallop condition or survival in the short term, although the power of the test to detect a 50% decrease in survival was low. The percentage of experimental scallops lost to different sources of mortality was also unaffected by the presence of C. gibba, as was the density of predators found in experimental enclosures. This study is the first to experimentally demonstrate the impact of an introduced marine mollusc on an endemic species in Australia. A possible mechanism underlying this impact is competition for food, as both species are suspension feeders which live in an environment where resource limitation may occur.

KEY WORDS: Bivalve molluscs · Exotic/introduced/non-indigenous species · Density manipulation · Resource limitation

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