Growth and population dynamics of the giant clam Tridacna maxima (Röding) at its southern limit ofdistribution in coastal, subtropical eastern Australia

The Solitary Islands Marine Park in northern New South Wales hosts eastern Australia’s southernmost coastal population of the giant clam Tridacna maxima. This small population of clams was monitored and measured over a 12-yr period to determine patterns of distribution, dynamics and growth rates. Most (31) of the 40 specimens found were present at the most offshore location (North Solitary Island) and growth rates were similar to those recorded on the southern Great Barrier Reef. Recruitment rates were very low (<2 yr across the whole Park) and loss of individuals was mostly associated with periods of large swell. The importance of North Solitary Island for Tridacna reflects the results of other studies demonstrating a strong tropical influence, mediated by the East Australian Current, at this, the most offshore island on the NSW coast.