Mercury (Hg) speciation in coral reef systems of remote Oceania: Implications for the artisanal fisheries of Tutuila, Samoa Islands.

We investigated Hg in muscle tissue of fish species from three trophic levels on fringing reefs of Tutuila (14°S, 171°W), plus water, sediment and turf alga. Accumulation of total Hg in the herbivore Acanthurus lineatus (Acanthuridae, lined surgeonfish, (n=40)) was negligible at 1.05 (±0.04) ng g(-1) wet-weight, (∼65% occurring as methyl Hg). The mid-level carnivore Parupeneus spp. (Mullidae, goatfishes (n=10)) had total Hg 29.8 (±4.5) ng g(-1) wet-weight (∼99% as methyl Hg). Neither A. lineatus or Parupeneus spp. showed a propensity to accumulate Hg based on body size. Both groups were assigned a status of "un-restricted" for monthly consumption limits for non-carcinogenic health endpoints for methyl Hg. The top-level carnivore Sphyraena qenie (Sphyraenidae, blackfin barracuda, n=3) had muscle tissue residues of 105, 650 and 741 ng g(-1) wet-weight (100% methyl Hg, with increasing concentration with body mass, suggesting that S. qenie >15 kg would have a recommendation of "no consumption".

Optimizing voluntary compliance in marine protected areas: a comparison of recreational fisher and enforcement officer perspectives using multi-criteria analysis.

A comprehensive list of planning criteria for optimizing compliance in Marine Protected Areas (MPAs) was compiled and used to compare the views of recreational fishers and compliance officers for facilitating voluntary compliance in the Port Stephens - Great Lakes Marine Park (PSGLMP). Expert working groups were tasked separately with: 1) criteria identification and weighting; 2) scoring of no-take zones; 3) prioritizing and determining uncertainty; and 4) analysis of results and sensitivity testing. Multi-Criteria Analysis (MCA) revealed that both groups had similar perspectives and recommendations, despite weighting the individual planning criteria differently. Significantly, "manageability" scores for no-take zones from MCA appeared to correlate well with past numbers of enforcement actions recorded for each zone. This provides empirical evidence that adopting manageability criteria during the planning of MPAs could lead to a marked increase in voluntary compliance. As a result, greater consideration to compliance planning during MPA design and zoning is recommended in order to optimize voluntary compliance. Whilst the majority of no-take zones in the PSGLMP case study were evaluated as being relatively effective in terms of optimizing voluntary compliance, there remains considerable potential to improve design, management and use of the poorer performing zones. Finally, the study highlighted the value of recreational fisher engagement in MPA planning processes to maximize voluntary compliance and manageability.

Marine genetic swamping: hybrids replace an obligately estuarine fish.

Populations of obligately estuarine taxa are potentially small and isolated and may lack genetic variation and display regional differentiation as a result of drift and inbreeding. Hybridization with a wide-ranging marine congener should introduce genetic variation and reduce the effects of inbreeding depression and genetic drift. However, high levels of hybridization can cause demographic and genetic swamping. In southeastern Australia hybridization occurs between obligately estuarine Black bream (Acanthopagrus butcheri) and migratory marine Yellowfin bream (Acanthopagrus australis). Here, we surveyed genetic variation at eight microsatellite loci and the mitochondrial control region of juvenile fish from five coastal lagoons (including temporal replication in two lagoons) (total n = 970) to determine the frequency and persistence of hybridization, and its likely consequence for the estuarine restricted A. butcheri. Of 688 juvenile fish genotyped 95% were either A. australis (347) or hybrids (309); only 5% (32) were A. butcheri. Most hybrids were later generation hybrids or A. butcheri backcrosses, which are likely multi-generational residents within lagoons. Far greater proportions of hybrid juveniles were found within two lagoons that are generally closed to the ocean (>90% hybrid fish within generally closed lagoons vs. 12-27% in permanently or intermittently open lagoons). In both lagoons, this was consistent across multiple cohorts of fish [79-97% hybrid fish (n = 282)]. Hybridization and introgression represent a major threat to the persistence of A. butcheri and have yet to be investigated for large numbers of estuarine taxa.

Experimental transplanting of Posidonia australis seagrass in Port Hacking, Australia, to assess the feasibility of restoration.

Over the last 50 years, about one-third of the original area of the seagrass Posidonia australis has been lost from Port Hacking (Australia) due to anthropogenic impacts. To assess the feasibility of restoring these seagrass meadows, healthy Posidonia rhizomes were transplanted to four impact sites and one control site. Survival rates of transplanted shoots were monitored in situ bi-monthly for 16 months and, at the end of the experiment, rhizome growth, shoot growth, shoot production and growth architecture were assessed by harvesting tagged rhizomes. A total of 575 shoots were transplanted and after 16 months 650 shoots were present. Four of the five sites exhibited high survival rates in the short term (less than six months) but only two impact sites, Burraneer Bay (BB) and Red Jacks Point (RJP), and the control site (CS) survived to the end of the experiment. Total number of shoots increased by 61% at CS, tripled at BB, but decreased by 22% at RJP. Rhizome growth varied significantly between site, from 22.3 +/- 1.4 cm yr(-1) at BB to 9.1 +/- 1.0 cm yr(-1) at RJP. Shoot growth did not vary significantly between sites and was approximately 2-3 cm yr(-1). At BB and CS there was substantial colonisation of the surrounding substrate, with new rhizomes, orthotropic shoots and transitional shoots produced. Survival of transplants appeared to depend on whether the factors that had caused the original loss of Posidonia were still operating in the study area.