Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

A decline in the abundance and condition of a native bivalve associated with Caulerpa taxifolia invasion

Jeffrey T. Wright A C , Louise A. McKenzie B and Paul E. Gribben B

A Institute for Conservation Biology and School of Biological Sciences, University of Wollongong, Wollongong, NSW 2522, Australia.

B Centre for Marine Biofouling and Bio-Innovation and School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia.

C Corresponding author. Email:

Marine and Freshwater Research 58(3) 263-272
Submitted: 18 August 2006  Accepted: 10 January 2007   Published: 9 March 2007


Caulerpa taxifolia is a fast-spreading invasive seaweed that threatens biodiversity in temperate Australian estuaries. To date, little is known about its effects on infauna. In the present study, we describe variation in demographic and life-history traits of the abundant infaunal bivalve, Anadara trapezia, in C. taxifolia and uninvaded habitats (seagrass and unvegetated sediments) at multiple sites across three estuaries in south-eastern New South Wales. Densities of A. trapezia were always lower in C. taxifolia than on unvegetated sediment, and lower in C. taxifolia than in seagrass at three out of four sites where they were compared. Dry tissue weight of A. trapezia was also lower in C. taxifolia than on unvegetated sediment at most sites, but was only lower in C. taxifolia than in seagrass at one of four sites. Populations were dominated by larger individuals (>45 mm length), but smaller individuals (35–45 mm length) were more common in C. taxifolia and seagrass. A. trapezia shell weight and morphology was variable and appeared weakly affected by invasion. Generally, our findings are consistent with the hypothesis that A. trapezia is negatively affected by C. taxifolia. However, C. taxifolia invasion appears complex and, at some places, its effects may not differ from those of native seagrass. There is a need for manipulative studies to understand the mechanisms underlying the effects of C. taxifolia on infauna.

Additional keywords: Anadara trapezia, infauna, invasive species.


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