Estuarine ecosystems are increasingly threatened by the introduction of non-indigenous species, and research suggests this may be facilitated by anthropogenic modification of habitat.

The construction of artificial structures (such as pilings and pontoons) provides a habitat resource in close proximity to vessel hulls that carry a wide range of non-indigenous fouling species including species of barnacles, mussels and other invertebrates.

Subtidal surveys of artificial and natural structures in Sydney Harbour revealed that vertical, shaded structures are favoured by non-indigenous invertebrate species and experiments suggested that shallow floating structures (analogous to pontoons) could also be hotspots for invaders.  Shallow floating structures create environmental conditions that closely resemble those on boat hulls and provide a suitable habitat for non-indigenous fouling species.

Native communities were primarily composed of macroalgae and these dominated both vertical and horizontal rocky reef.  Native rocky reef communities appear relatively resistance to invasion in the shallow subtidal, but the findings from this study suggest that rock wall communities are vulnerable to invasion therefore should be protected from disturbance.

This research project is led by Dr. Katherine Dafforn from UNSW Australia.