Marinas have been shown to contribute elevated concentrations of copper (Cu) to marine waters. The Cu can come primarily from antifouling paints which are designed to discourage biofouling of boat hulls. Legislation in Washington State, USA is being developed to limit or regulate the amount and rate of diffusion of Cu from antifouling paints. This study provides baseline data for Cu in five marinas of different configuration and size within Puget Sound, a large fjord estuary. Samples were collected over a year from multiple environmental media. We find strong evidence that Cu accumulates inside marinas to higher concentrations than outside marinas. Marinas that are more enclosed accumulated higher concentrations of Cu than more open marinas. Using a power analysis, we assessed the adequacy of the baseline dataset to measure progress as a result of future legislation towards the reduction of Cu to Puget Sound from marinas.

Populations of macro-algae and sessile invertebrates have precipitously declined in urbanised coastal waters in Australia since European occupation. Responses of healthy subtidal sessile assemblages to cumulative impacts and types of urban impacts were measured in one of the most polluted estuaries in Australia - the Derwent Estuary - by transplanting sessile communities established on pavers to locations adjacent to marinas, sewerage outfalls, fish farm cages, and stormwater discharges, each with associated controls. Reef communities translocated to sites adjacent to central urban pollution sources (within 5 km of Hobart) lost canopy-forming algae. Fish farms, marinas, and storm water drains were all characterised by higher filamentous algal cover than their controls. Marinas were associated with losses in canopy and foliose algae. Restoration of subtidal reef near highly urbanised areas is unlikely to be successful until current pollution levels are dramatically reduced.

Polychlorinated biphenyl (PCB) concentrations were determined in surface sediments from three recreational marinas in San Diego Bay, California. Total PCB concentrations ranged from 23 to 153, 31–294, and 151–1387ngg−1 for Shelter Island Yacht Basin (SIYB), Harbor Island West (HW) and Harbor Island East (HE), respectively. PCB concentrations were significantly higher in HE and PCB group composition differed relative to HW and SIYB, which were not significantly different from each other in concentration or group composition. In marina sediments there was a predominance (82–85%) of heavier molecular weight PCBs with homologous groups (6CL-7CL) comprising 59% of the total. In HE 75% of the sites exceeded the effect range median (ERM), and toxicity equivalence (TEQ dioxin-like PCBs) values were higher relative to those of HW and SIYB, suggesting a potential ecotoxicological risk.

Biological invasions are a major threat to the world's biota and are considered a major cause of biodiversity loss. Therefore, world marine policy has recognized the need for more marine protected areas (MPAs) as a major tool for biodiversity conservation. The present work experimentally evaluated how protected communities from an offshore island can face the settlement and/or expansion of nonindigenous species (NIS). First, NIS colonization success in marine protected and marina communities was compared by deploying PVC settling plates at the Garajau MPA and Funchal marina (SW Madeira Island). Then, the settling plates from the MPA were transferred to Funchal marina to test their resistance to NIS invasion under high levels of NIS pressure. Results indicated that the structure and composition of fouling communities from the MPA differed from those collected in the marina. Interestingly, communities from the protected area showed lower NIS colonization success, suggesting some degree of biotic resistance against NIS invasion.

Hull fouling has been a driving force behind the development of most modern marine antifouling coatings that mainly contain copper based biocides to inhibit growth of fouling organisms. Despite these efforts, several non-indigenous species continue to be transferred via hull-fouling worldwide. In this study we designed a disturbance gradient with three commercial antifouling paints applied to PVC settling plates with different concentrations of copper oxide and allowed colonization of fouling communities in four marinas located at the Madeira Archipelago (NE Atlantic). Overall, the antifouling treatments were effective in decreasing the diversity of fouling communities and spatial variability across marinas was observed. Increasing exposure to metal pollutants decreases both species cover and total diversity, independently of their native or NIS condition. However, evidences found suggest that long-term effects of copper based antifouling coatings can be modulated by metal-resistant species allowing a secondary substrate for the epibiosis of other species to establish.