Mine waste disposal leads to lower coral cover, reduced species richness and a predominance of simple coral growth forms on a fringing coral reef in Papua New Guinea.

A large gold mine has been operating at the Lihir Island Group, Papua New Guinea since 1997. The mine disposes of waste rock in nearshore waters, impacting nearby coral communities. During 2010, 2012 we conducted photographic surveys at 73 sites within 40 km of the mine to document impacts of mining operations on the hard coral communities. Coral communities close to the mine (∼2 km to the north and south of the mine) were depaurperate, but surprisingly, coral cover and community composition beyond this range appeared to be relatively similar, suggesting that the mine impacts were limited spatially. In particular, we found mining operations have resulted in a significant decrease in coral cover (4.4% 1.48 km from the disposal site c.f. 66.9% 10.36 km from the disposal site), decreased species richness and a predominance of less complex growth forms within ∼2 km to the north and south of the mine waste disposal site. In contrast to the two 'snapshot' surveys of corals performed in 2010 and 2012, long term data (1999-2012) based on visual estimates of coral cover suggested that impacts on coral communities may have been more extensive than this. With global pressures on the world's coral reefs increasing, it is vital that local, direct anthropogenic pressures are reduced, in order to help offset the impacts of climate change, disease and predation.

Restricted movements and mangrove dependency of the nervous shark Carcharhinus cautus in nearshore coastal waters.

This study used a network of acoustic receivers deployed around a no-take zone in Mangrove Bay, within the Ningaloo Reef Marine Park in Western Australia, to study residency and habitat preference of a small coastal shark, the nervous shark Carcharhinus cautus. Twelve C. cautus were tagged with acoustic tags and monitored for up to 579 days. Based on individuals detected within the receiver array for at least 2 months, C. cautus had small core (50% kernel utilization distribution, KUD) and home ranges (95% KUD) of 0.66 and 3.64 km2, respectively, and showed a strong habitat preference for mangroves, which are only found in the no-take zone. This resulted in C. cautus spending most of their detected time within the no-take zone boundaries (mean = 81.5%), showing that such a protected area could be beneficial to protect this species from extensive fishing pressure and local depletion, where required. Not all C. cautus remained within the acoustic array, however, suggesting that individual variations occur and that not all individuals would benefit from such protection. This study provides important information about the habitat, residency and movements of C. cautus that can be used for management and conservation. The strong affinity and residency of C. cautus within a mangrove-fringing coastline, emphasizes the importance of mangrove habitat to the species and suggests that such preferences can be used to design appropriate no-take zones for this species or others with similar habitat preferences.

Effects of trawling on the diets of common demersal fish by-catch of a tropical prawn trawl fishery.

The ecological effect of prawn trawling on the benthos of the Gulf of Carpentaria, northern Australia, was investigated by examining stomach contents of common demersal fishes incidentally caught as by-catch in the fishery. Fishes were collected from high and low fishing intensity sites in three regions based on vessel monitoring system data. The diets of eight species of benthic fish predators were compared between regions and fishing intensities. A regional effect on diet was evident for seven species. Only one generalist species had no significant difference in diet among the three regions. For the comparisons within each region, five predator species had significantly different diet between high and low fishing intensities in at least one region. Across the three regions, high fishing intensity sites had predators that consumed a greater biomass of crustaceans, molluscs and echinoderms. At low fishing intensity sites, predators had diets comprising a greater biomass of cnidarians and teleosts, and a different assemblage of molluscs, crustaceans and fishes. These changes in diet suggest that there may have been a shift in the structure of the benthic community following intensive fishing. Analysis of predator diets is a useful tool to help identify changes in the benthic community composition after exposure to fishing. This study also provided valuable diet information on a range of abundant generalist benthic predators to improve the ecosystem modelling tools needed to support ecosystem-based fisheries management.