The wreck of the MV Rena: spatio-temporal analysis of ship-derived contaminants in the sediments and fauna of Astrolabe Reef

ABSTRACT

The October 2011 sinking of the container ship MV Rena on Astrolabe Reef, New Zealand, provided a rare opportunity to examine the fate of shipwreck-derived contaminants on an offshore rocky reef and food chain. Analyses of trace metals, polycyclic aromatic hydrocarbons (PAHs) and organotins indicated significant but localised contamination of Astrolabe Reef but not of nearby Mōtītī Island. Three years after the grounding, PAH concentrations were greater in sediments at Astrolabe (up to 131?mg kg^?1) than at control locations, while organotins from the ship's antifouling hull paint were found exclusively in Astrolabe Reef sediments and biota. Over 80% of Astrolabe sediment samples contained tributyltin at concentrations above guideline sediment levels (>0.07?mg kg^?1). Tributyltin and its decomposition products were also recorded in sea urchins, gastropods, lobster and fishes at concentrations up to 0.2?mg kg^?1. Wreck and cargo-derived metals, particularly copper, tin and zinc, were present in some Astrolabe sediment samples above Australia and New Zealand Environment and Conservation Council guideline concentrations. However, there appeared to be only limited transmission of metals through the food chain. Copper, tin and zinc were recorded at greater concentrations in Astrolabe sea urchins and gastropods compared to control specimens, while metal concentrations in other biota were comparable across impact and control sites. Despite over 3 years having passed since the Rena grounding, the data series does not show any upward or downward trends in contaminant concentrations on Astrolabe Reef. Consequently, there is uncertainty about the long-term implications of the Rena grounding for the ecology of Astrolabe Reef.     

In situ sampling reveals rapid uptake and depuration of polycyclic aromatic hydrocarbons by surf clams (Paphies subtriangulata) affected by the Rena oil spill

ABSTRACT

To investigate the uptake and depuration of polycyclic aromatic hydrocarbons associated with the Rena oil spill we sampled the surf clam Paphies subtriangulata at two open coast locations (6?km apart) just prior to oil coming ashore (7 October 2011), then at 1–3 week intervals for the next 4 months. Total polycyclic aromatic hydrocarbons (tPAH) increased at both sites from 1 to 96–124?µg?kg^?1 (wet weight) by 18 October before declining to low levels (<4?µg?kg^?1) by February 2012. Ongoing sampling throughout 2012–2014 included three additional sites to the north east (up to 30?km away) and a site 5?km to the south east revealing tPAH levels generally <10?µg?kg^?1 except in October 2013 where levels ranged between 39–45?µg?kg^?1 at all sites. A comparison of PAH component profiles with oil-contaminated beach sediment indicated that the high levels observed in surf clams between October–December 2011 were clearly associated with the Rena spill. However, the October 2013 peak had a PAH profile inconsistent with weathered Rena oil, suggesting an alternative source of contamination. Our results highlight the potential for P. subtriangulata as a PAH monitoring tool but recognise more study is needed to better quantify baseline levels and uptake and depuration dynamics.     

Effects of the MV Rena oil spill on intertidal rocky reefs in the Bay of Plenty,New Zealand

In the weeks following the 2011 Rena oil spill, a series of surveys was initiated on eight rocky intertidal reefs to describe the distribution of oil and to assess the impacts of oil on ecological communities. Consistent but relatively low cover of oil occurred at two sites (Mt Maunganui and Moturiki). The area covered by oil had decreased by c. 90% after 5 months due to natural weathering processes. There were immediate effects of oil fouling on the mussel Limnoperna pulex and its associated fauna, with reductions in the number of mussels and infaunal taxonomic richness. However, no ecological effects on any of the communities were detectable after 1 month. Overall, the ecological effects of the Rena oil spill on rocky shore intertidal communities were small and not long-lasting, but we stress that this does not consider potential sublethal effects and their consequences on organisms.     

Anthropogenic organic contaminants in the effluent of a combined sewer overflow: impact on Boston Harbor

Effluent from a large combined sewer overflow (CSO) in Boston and receiving waters near the CSO outfall were sampled during dry and wet weather conditions. Surficial sediments were also collected from the vicinity of the CSO and at nearby sites. The samples were analyzed for a variety of organic constituents including organic carbon and nitrogen, linear alkylbenzenes (LABs), coprostanol and polychlorinated biphenyls (PCBs). As judged by the presence of waste-specific markers (LABs, coprostanol), the CSO effluent contains sewage under both dry and wet weather conditions. When rainfall occurs, the concentration of suspended solids and all organic constituents in the particulate phase increase, ultimately approaching those characteristic of untreated sewage. The concentrations of LABs and PCBs in the effluent are strongly correlated, indicating that PCBs in the CSO are derived from sewage inputs. During heavy rainfall, the vast majority (> 90%) of the hydrophobic organic substances are associated with suspended particulate matter, whereas during dry weather, a significant fraction resides in the operationally defined 'dissolved' phase. Estimates of the mass emission rates of CSO constituents show that > 70% of the suspended particles and > 90% of the particulate organic carbon, hydrocarbons and trace organics are discharged during wet weather. Particles in the receiving water appear to be strongly influenced by the CSO effluent during wet weather. Concentrations of PCBs in surficial sediments near the CSO are correlated with those of coprostanol and the LABs, indicating that these compounds are derived from similar sources. Based on the observed correlations, approximately 60-80% of the sedimentary PCBs originate from sewage. Comparison of sigma LAB/coprostanol ratios of effluent particles, surficial sediments and sewage sludges suggest that the vast majority of the marker compounds and the PCBs in sediments are not from the CSO, but are derived from one of two sewage treatment plants that discharged sludge into the harbor until 1991. The sludge-derived contaminants were probably carried by tidal currents into Dorchester Bay and deposited in shallow, quiescent embayments where sedimentation is favored. These results illustrate the potential importance of long-range transport of waste-derived contaminants in urban harbors and their rapid accumulation in localized depocenters.     

Molecular and biochemical tricks of the research trade: -omics approaches in finfish aquaculture

Profitability of fish farming can be undermined by a suite of biological constraints. Effects of these constraints on the biology of the animal, the functioning of a tissue, or the quality of the final filleted product can be detected with very sensitive hi-tech approaches, grouped by the term ‘-omics’. These -omics technologies further present powerful tools for the genetic selection of diverse traits and, as such, will contribute substantially to the future development of the aquaculture sector. Sustainability issues of importance to the industry, such as environmental impacts, use of therapeutants, fish health management and fishmeal replacement, can again be aided, at least in part, through the effective use of -omics technologies. It thus appears that -omics technologies may be a key tool for the responsible growth of intensive aquaculture in the 21st century. In this paper we review the current status of -omics technologies and the potential for application within the aquaculture industry.     

Environmental effects of the MV Rena shipwreck: cross-disciplinary investigations of oil and debris impacts on a coastal ecosystem

ABSTRACT

The 2011 wreck of the MV Rena off the northeast coast of New Zealand, and subsequent impacts, has been called New Zealand's worst ever maritime environmental disaster. It is certainly one of the world's most complex as it involved a pollutant combination of oil and dangerous goods debris in a dynamic oceanic environment adjacent to a pristine coastline. Heavy fuel oil, shipping containers loaded with cargo, and a wide range of wreck debris and contaminants were spread along hundreds of kilometres of coastline of the Bay of Plenty. Much of this landed on sandy beaches and rocky shores. Broken containers released often toxic substances, and the wreck itself slid down the pinnacle of the wreck site at Astrolabe Reef (Otaiti). The reef remains heavily contaminated, with substantial remnants of the ship and its cargo present, and chemical effects still evident in some species. Here we present the background and timeline of events that unfolded after the grounding. The following articles contain the results of the ensuing chemical, toxicological and ecological studies of contamination and environmental recovery. At the time of writing, numerous legacy issues remain.