The effects of copper antifouling paints and marinas on the ecology of marine sessile epifaunal assemblages

This thesis has used a field based approach to assess the effects of copper liberated from antifouling paints on sessile epifaunal (or fouling) assemblages in southeastern Australia. In the field the effects of dosed copper may be influenced by site conditions, or because the organism has developed tolerance to exposure. To explore these possible effects experiments were conducted inside and outside of two enclosed marinas. Marinas were located at St Kilda (Port Phillip Bay) and Hastings (Western Port Bay), Victoria. At St Kilda, sites were located inside the St Kilda Marina and at St Kilda Pier. At Hastings, sites were located inside Westernport Marina and at Hastings Jetty. Additional sites were also sampled occasionally over the study period. Studies were carried out between 1997-1999. A novel copper dosing system was developed for use in the field.

Studies comparing epifaunal assemblages inside and outside the two marinas found that marinas produced different assemblages. The marinas exerted common effects on some functional groups, but effects at the species level differed at each marina.

The effects of dosed copper inside and outside the two marinas were tested on: i) the early recruitment of assemblages, and ii) the growth rate and competitive ability of colonial fouling organisms. Results were characterised by high spatial and temporal variability. Copper dose affected a number of species recruiting to the plates but was rarely found to significantly alter growth rates of the colonial organisms; this may be attributed to the high variability observed in growth rates. The competitive ability of colonies was not found to be affected by copper dose or marinas, but few experiments examined this aspect.

Reciprocal transplants of settlement plates between sites and copper doses showed that the effect of marinas on assemblages was more important than dosed copper, even though dose levels were well above background concentrations. This is probably due to a large number of factors associated with marinas over and above the effects of increased background heavy metal pollution. Several taxa appeared to adapt to local conditions or copper dose and some appeared to show heterogeneity in response to copper dosing or an ability to acclimate to dose. These types of findings have important implications for the manner in which we apply the findings of traditional laboratory-based ecotoxicology experiments to environmental management.