Environmental impact of the MV CITA on the foreshore of Porth Hellick, Isles of Scilly

The grounding of the container feeder vessel MV CITA on Newfoundland Rocks, Isles of Scilly, had an effect on the surrounding biota and benthic environment. Included in the CITA's cargo were five 40 ft containers holding pallets of polyester film used in the production of audio and visual recording tapes. The wreckage presented a minor but potentially chronic source of pollution through the delayed release of polythene film, which was left on the seabed as it was considered insufficiently valuable to warrant salvage. The polythene disintegrated and was washed upon the foreshore of Porth Hellick in minute shreds. The adjacent foreshore and two control sites within the islands were analysed using a 5-strand line and vegetation survey with 10 random quadrats within each line to determine the environmental impact of the polythene.     

The orbit, mass, and albedo of transneptunian binary (66652) 1999 RZ253

We have observed (66652) 1999 RZ₂₅₃ with the Hubble Space Telescope at seven separate epochs and have fit an orbit to the observed relative positions of this binary. Two orbital solutions have been identified that differ primarily in the inclination of the orbit plane. The best fit corresponds to an orbital period, days, semimajor axis a=4660±170 km and orbital eccentricity e=0.460±0.013 corresponding to a system mass m=3.7±0.4×¹⁰¹⁸ kg. For a density of the albedo at 477 nm is p₄₇₇=0.12±0.01, significantly higher than has been commonly assumed for objects in the Kuiper belt. Multicolor, multiepoch photometry shows this pair to have colors typical for the Kuiper belt with a spectral gradient of 0.35 per 100 nm in the range between 475 and 775 nm. Photometric variations at the four epochs we observed were as large as 12±3% but the sampling is insufficient to confirm the existence of a lightcurve.     

Non-conservative P and N fluxes and net ecosystem production in San Quintin Bay,México

San Quintin Bay, Mexico, is a hypersaline coastal lagoon where the main external forcing of physical and biogeochemical processes is oceanic. Non-conservative fluxes of inorganic N (ΔDIN) and P (ΔDIP), and aspects of net ecosystem metabolism were studied in this lagoon during August 1995, August 1996, and February 1996, by following the LOICZ budgetary modeling approach. The whole-system water exchange time during summer (≈13 d) was shorter than in winter (≈26 d) as northwesterly winds enhancing mixing with the ocean are more intense during the spring-summer upwelling season. Whole-bay ΔDIP values of +0.2 to +0.3 mmol m^?2 d^?1 in August, and <+0.01 mmol m^?2 d^?1 in February indicate that the system is a net source of dissolved inorganic phosphorus (DIP). DIP fluxes from the Bay to the ocean during August are probably balanced by a net import of particulate organic matter between 1,000–1,300 × 10³ mol C d^?1, equivalent to a net ecosystem production (NEP) between ?24 and ?31 mmol C m^?2 d^?1. ΔDIN showed opposite trends in August 1995 and August 1996, with a net import of 13×10³ mol N d^?1 and a net export of 30× 10³ mol N d^?1, respectively. However, N fixation minus denitrification (“apparent denitrification”) estimates of ≈?4 mmol N m^?2 d^?1 in both periods indicate that San Quintin Bay is a net sink of nitrogen. Results from a 3-box model indicate that during summer Box C, adjacent to the ocean, contributed 70–80% of the excess DIP produced in the whole-system. This observation and high apparent denitrification values of ≈?7 mmol N m^?2 d^?1 at the entrance of the Bay, suggest that the net heterotrophic condition of San Quintin Bay in summer is largely determined by imports of labile phytoplanktonic carbon generated in the adjacent ocean during upwelling.A net flux of organic carbon of 30×10⁶ mol C yr^?1 was estimated from Box C, adjacent to the ocean, to Box B, locally known as Bahia Falsa, which is the area designated for oyster aquaculture in the lagoon. It is estimated that this net organic carbon supply is almost equivalent to the annual oyster food demand; our estimate is that oyster aquaculture in San Quintin Bay accounts for the vast majority of the net heterotrophy of Bahia Falsa.     

Author Index

Authors Index

Author Index     

Data use and information creation: challenges for marine scientists and for managers

In the coastal waters of European countries and in the offshore waters of the north-east Atlantic, there is an increasing need for scientists to meet challenging objectives, such as to identify meaningful measures of 'quality', and to recommend 'indicators' to underpin implementation of directives, conventions, statutes and other more informal national and international initiatives. Those indicators may relate to particular species or habitats, to changes in physical and chemical characteristics, and even to the use to which the system is put. The problems to be overcome are difficult, but new and developing approaches will make a significant contribution. The approaches include: criteria to identify 'sensitivity' and 'importance', structures to organise information and electronic information resources to access data.The real challenge is to make the results of the various scientific initiatives relevant to and understandable by a wide range of customers with similar overlapping requirements, and thus make a genuine contribution to protecting the marine environment. Above and beyond that is the need for scientists to drive the agenda to enable real and lasting progress to be made towards ecosystem-based management of our seas and a proper consideration of what 'sustainability' may mean in the marine environment and how we utilise its resources.     

Spills of fuel oil #6 and Orimulsion can have indistinguishable effects on the benthic meiofauna

Fuel oil #6 is used for the production of electrical power in the United States. Orimulsion is being considered as an alternative fuel, but its value and risk compared to fuel oil #6 need to be assessed. Our study examined the relative impact of accidental spills of the two hydrocarbons on the meiofaunal community. To do so, we maintained microcosms of the shallow, sandy, subtidal environment for three months. Treatment microcosms received a single application of hydrocarbon-coated sand. As indicators of effect, we used copepod and nematode abundance and copepod species diversity, sex ratio, fecundity, age structure, and neutral-lipid content. A comparison of the hydrocarbon treatments showed no significant differences. The tests had adequate power to detect ecologically significant changes. Our results indicate that a spill of Orimulsion would have approximately the same impact as a spill of fuel oil #6 on the meiofauna.     

Environmental determinism in Holocene research: causality or coincidence?

The past decade has seen a revival of environmental determinism in palaeoenvironmental research, with palaeoclimatic shifts implicated in the collapse of many past civilizations. Implicit in these studies is a belief that the observed cultural transitions can be causally related to the magnitude of climatic change. However, examination of the processes of these declines suggests that many exhibit patterns characteristic of complexity cascading within self-organized systems. If so, the nonlinear nature of these systems' responses to external forcing means that the assumption of causality in many of these cases should be considered questionable.     

The cultural context of forest degradation in adjacent Purépechan communities, Michoacán, Mexico

Recent changes in the cultural and forest landscapes of the Meseta Purépecha in Michoacán, Mexico as a result of forest degradation underscore the complexity of forest change processes in the tropical highlands of Latin America. Differences in community perception and forest structure and composition between the furniture-making and lumber-producing towns of Pichátaro and Sevina, Purépechan indigenous communities located amidst pine forests on Michoacán's volcanic plateau illustrate the dynamics of this process. We base our comparisons on interviews and field measures of forest structure. Our results show dramatic changes in the forests and cultural landscapes of both communities during the past decade. Following high regional timber exports during the early 1990s, Sevina shifted from a self-sufficient to a timber importation community. By comparison, communal forests and individual parcels in Pichátaro continue to provide wood for approximately 300 wood shops. Field data and forest stand maps confirm the perception of forest degradation in both communities. While Pichátaro has maintained a larger and more diverse forest base to date, stand structure data indicate selective harvesting has led to a shift in dominance toward the less economically desirable pine species and oak. Deforestation and degradation of Sevina and Pichátaro's community forests are symptomatic of both the Meseta Purépecha and Mexico in general. Current forest conditions in both communities justify local, regional, and national concerns regarding declining biodiversity and sustainable economies.