The MV Rena shipwreck: time-critical scientific response and environmental legacies

ABSTRACT

The sinking of the MV Rena on Astrolabe Reef (Otaiti) in the Bay of Plenty, New Zealand, resulted in the release of oil and ship debris, including dangerous goods carried as cargo. Two key questions of concern to the public and environmental managers were posed immediately: what was the impact of the Rena oil spill and how long would it take for the marine environment to recover? The research that began immediately after the ship grounded provided answers, as documented in this special issue.     

THE HYDROGEOLOGY OF GHANA

SUMMARY

Many hydrological systems exhibit long periods of quiescent behaviour, broken only occasionally by short periods of comparatively intense activity. Clear examples arise in stream run-off measurements and in ground water table observations. The number of measurements recorded can then be considerably reduced by reducing the frequency of recording over the quiescent periods. The paper describes an algorithm whereby this reduction is attained in an optimum manner. When recordings can be accepted directly by a computer, the algorithm simply provides a translation programme Whereby the quality of data may be very considerably reduced. Other applications are, however, discussed.

The problems of Optimum representations is first presented, and choices of norm indicated. Using a particular norm, it is shown that the optimum representation is characterised, under certain limiting conditions, by the property that the second moments of the second derivatives are constant over all optimum intervals. This characterisation is used to construct an iterative difference scheme, whereby a certain truncation error is accepted. Sufficient conditions for stability of the scheme are determined and these incorporated into a computer programme. The programme has been tested on a variety of data with satisfactory results. In conclusion, a further development of the method is indicated.     

Composition and temperatures of the topside ionosphere over Arecibo

Results of analysis of about 150 autocorrelation functions are presented for the period from about 2300 hr on 5 October to about 1200 hr on 7 October 1967. A large percentage concentration of helium ions are observed. It reaches a value as high as 50 per cent with a maximum at around 800 km. Downward heat fluxes deduced from the temperature variations yield a value of about 2–2.5 × 10⁹ eV cm^?2 sec^?1 during the period 1200–1600 hr and a value of about 1.5 × 10⁸ eV cm^?2 sec^?1 during the period 0100–0400 hr at night. These agree well with other measurements. The O⁺ ions are found not to be in diffusive equilibrium, and from the O⁺ fluxes and the electron density profiles, the O⁺ drift velocity has been estimated. It is found that the speed can be as high as 1–5 × 10³ cm sec^?1 even at altitudes as high as 700 km.     

Emerging Geographies of Conservation and Indigenous Land in Australia

International examples of interactions between Indigenous peoples and the new conservation paradigm come mainly from developing countries and suggest divisions over priorities. As a Western settler society, Australia is at a critical time in conservation and Indigenous peoples' rights. Innovative approaches to conservation are promoted. The role and influence of non-governmental organisations is increasing. Indigenous peoples' rights to land are recognised and Indigenous involvement in conservation is growing. Yet, despite Australia being considered a leader in these arenas, particularly the latter, there has been little analysis of the relationship between innovative approaches to conservation and Indigenous Australians under the new paradigm. This paper describes how the spatial manifestations of approaches under the new conservation paradigm and Indigenous land in Australia are creating new geographies. We identify geographies of overlap, dichotomy and absence. The paper identifies research needs into these geographies, including: examining the influence of ‘recognition’ in engagements between conservation and Indigenous Australians; investigating the impacts of approaches under the new paradigm such as scaling-up, territorialism and differing governance structures on Indigenous Australians; and questioning the social responsibilities of the non-governmental organisations towards Indigenous Australians.     

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.     

Decoupling the effects of deforestation and climate variability in the Tapajós river basin in the Brazilian Amazon

Tropical river basins are experiencing major hydrological alterations as a result of climate variability and deforestation. These drivers of flow changes are often difficult to isolate in large basins based on either observations or experiments; however, combining these methods with numerical models can help identify the contribution of climate and deforestation to hydrological alterations. This paper presents a study carried out in the Tapaj?s River (Brazil), a 477,000 km² basin in South‐eastern Amazonia, in which we analysed the role of annual land cover change on daily river flows. Analysis of observed spatial and temporal trends in rainfall, forest cover, and river flow metrics for 1976 to 2008 indicates a significant shortening of the wet season and reduction in river flows through most of the basin despite no significant trend in annual precipitation. Coincident with seasonal trends over the past 4 decades, over 35% of the original forest (140,000 out of 400,000 km²) was cleared. In order to determine the effects of land clearing and rainfall variability to trends in river flows, we conducted hindcast simulations with ED2 + R, a terrestrial biosphere model incorporating fine scale ecosystem heterogeneity arising from annual land‐use change and linked to a flow routing scheme. The simulations indicated basin‐wide increases in dry season flows caused by land cover transitions beginning in the early 1990s when forest cover dropped to 80% of its original extent. Simulations of historical potential vegetation in the absence of land cover transitions indicate that reduction in rainfall during the dry season (mean of ?9 mm per month) would have had an opposite and larger magnitude effect than deforestation (maximum of +4 mm/month), leading to the overall net negative trend in river flows. In light of the expected increase in future climate variability and water infrastructure development in the Amazon and other tropical basins, this study presents an approach for analysing how multiple drivers of change are altering regional hydrology and water resources management.