Abstract
Pollution from the grounding or sinking of ships can have long lasting effects on the recovery and dynamics of coastal ecosystems. Research on the impact of copper (Cu) pollution from the 2011 MV Rena shipwreck at the Astrolabe Reef (Otaiti), New Zealand, 5 years after the grounding, followed a multi-method and multi-disciplinary approach. Three independent measures of aqueous Cu using trace-element-clean-techniques substantiate the presence of high total, total dissolved (<2 µm) and elevated bioavailable Cu in the water column immediately above the aft section of the wreck where the highest sedimentary load of Cu was located. Intermittently elevated concentrations of strong Cu-binding ligands occurred in this location, and their binding strength was consistent with ligands actively produced by organisms in response to Cu induced stress. The recruitment of benthic invertebrates was modified at the high-Cu location. Taxonomic groups usually considered robust to pollution were restricted to this site (e.g. barnacles) or were the most abundant taxa present (e.g. foraminifera). Our results demonstrate that Cu-contaminated sediments can impose a persistent point source of Cu pollution in high-energy reef environments, with the potential to modify the composition and recovery of biological communities.
Highlights
Between 2004 and 2014, 1,271 ships were lost at sea[1]
The [CuT], [dissolved Cu filtered at 0.2 μm (dCuT)] and [CuDGT] fractions varied coherently across the sample set (Table 1; Fig. 4) with markedly higher Cu concentrations encountered at the centre site
We suggest that the dynamic variability in the concentration of colloidal/particulate Cu in these coastal settings led to disparities between samples collected contemporaneously for CuT and dCuT
Summary
Between 2004 and 2014, 1,271 ships were lost at sea[1]. The causes may have included collision, adverse weather, loss of stability due to cargo movement or rupture of cargo tanks, explosions, uncontrollable fire, piracy, inadequate vessel maintenance and crew negligence or incompetence. While the environmental effects and legacies of most lost ships are unknown, contamination and subsequently environmental degradation are certain to occur. Shipwrecks do occur on coastlines where there are public or governmental expectations around gaining an understanding of the environmental consequences of maritime casualties. One example of a relatively accessible shipwreck is the MV Rena[4], which grounded and sank in 2011 at Otaiti (Astrolabe Reef; Fig. 1), in New Zealand’s Bay of Plenty. The major components of the shipwreck lie at depths ranging from −3 m to −60 m (Fig. 2). These physical and environmental factors have made it challenging to conduct both salvage and environmental monitoring activities. Perhaps of greatest interest in trying to understand the long-term chemical and ecological impacts of the Rena is the fate of some 7 to 12 tonnes of granulated Cu (clove grade)[2,4,5,6,7,8,10] which remain trapped beneath the wreck
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