Homochirality as the signature of life: the SETH Cigar

A characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images. It is therefore suggested that a search for extra-terrestrial life can be approached as a Search for Extra-Terrestrial Homochirality (SETH). A novel miniaturized space polarimeter, called the SETH Cigar, is described which could he used to detect optical rotation as the homochiral signature of life on other planets. Moving parts are avoided by replacing the normal rotating polarizer by multiple fixed polarizers at different angles as in the eye of the bee. It is believed that homochirality will be found in the subsurface layers on Mars as a relic of extinct life.     

Migrating to learn and learning to migrate: a study of the experiences and intentions of international student migrants

"The research reported here evaluates whether students come to the UK mainly for educational reasons, and therefore perceive their stay as temporary, or whether emigration for study is being used as part of a conscious strategy by people intending to become future labour migrants.... The simplest interpretation of the results appears to be that migration, experienced as a result of international moves for study purposes, does not influence planning of further migration moves. But the research also indicates that migration for education is closely tied to other types of population redistribution and should be treated by population geographers as an integral part of international migration systems." Data were collected by questionnaire survey from 349 engineering students at Hong Kong universities and 82 Hong Kong students studying engineering in the UK.     

Recovery of polluted ecosystems: the case for long-term studies

Recovery of marine ecosystems from pollution has tended to receive less attention than the study of new or continuing impacts, but such studies are important in charting recovery from acute incidents and following legislation to deal with chronic contamination. Recovery is inevitably a long-term process, and where such studies have been made they are often too short-lived. Interest quickly wanes following an acute incident and governmental bodies rapidly switch to new legislative priorities for chronic inputs. We review three case studies: recovery of dogwhelk populations after local extinction by tributyl tin leachates from anti-fouling paints; recovery of rocky shore communities from oil spills; and recovery of estuarine ecosystems from industrial and urban development. We then make some generalisations about recovery processes before making a plea for long-term studies of polluted areas.     

Array technology as a tool to monitor exposure of fish to xenoestrogens

A variety of anthropogenic chemicals are capable of binding to the estrogen receptor of vertebrate species. Binding of these compounds can interfere with homeostasis by disrupting normal gene expression patterns. The purpose of this study was to investigate the feasibility of applying array technology as a monitoring tool for detecting the presence and distribution of estrogenic compounds in coastal habitats using sheepshead minnows as our model. cDNA clones that were isolated from differential display, including vitellogenin alpha and beta, vitelline envelope protein (ZP2), and transferrin, among others, were spotted on the macroarray. The results of these experiments demonstrate a characteristic expression pattern of estrogen responsive genes in sheepshead minnows exposed to 17 beta-estradiol (E2).     

Evaluation of toxicity in tributaries of the Mersey estuary using the isopod Asellus aquaticus (L.)

Increasing numbers of industrial, agricultural and natural chemicals are present in sewage effluent and are known to elicit toxic effects in laboratory exposures, but little is known of their combined sub-lethal effect in the field. In this study, a combination of esterase activity and ventilation rate assays was performed to determine the neurological and physiological function of the freshwater crustacean Asellus aquaticus (L.) at sites above and below a sewage treatment works (STW). Cholinesterase and carboxylesterase activities were significantly inhibited (n=8, P<0.05) and ventilation rates increased (n=8, P=0.0001) in A. aquaticus at STW sites compared to those from reference sites, indicating a decrease in neurological and physiological function. The ecological relevance of these findings for the population dynamics of the organisms in the field is discussed.     

Monitoring the development of intertidal habitats on former agricultural land after the managed realignment of coastal defences at Tollesbury, Essex, UK

The managed realignment of coastal defences and subsequent creation of intertidal habitats is one of several 'soft' engineering options that could reduce the costs of maintaining embankments and at the same time deliver environmental benefits. The managed realignment at Tollesbury was one of the first in the UK, undertaken as an experimental test case to improve understanding of the practical techniques and processes involved. Independent studies were undertaken on the development of soils, benthic invertebrates and vegetation within the site in addition to methods of enhancing the process of natural colonisation of saltmarsh plants. Bathymetric and vegetation monitoring were undertaken on the adjacent estuary to determine any breach effect that may be attributed to the realignment. This paper summarises the results from the vegetation, sedimentation and invertebrate monitoring and discusses the implications for other managed realignment schemes in the UK.     

The significance of dilution in evaluating possible impacts of wastewater discharges from large cruise ships

In response to public concerns about discharges from large cruise ships, Alaska's Department of Environmental Conservation (ADEC) sampled numerous effluents in the summer of 2000. The data showed that basic marine sanitation device (MSD) technology for black water (sewage) was not performing as expected. Untreated gray water had high levels of conventional pollutants and surprisingly high levels of bacteria. Both black water and gray water discharges sometimes exceeded state water quality standards for toxicants. The state convened a Science Advisory Panel (the Panel) to evaluate impacts associated with cruise ship wastewater discharges. The effluent data received wide media coverage and increased public concerns. Consequently, legislative decisions were made at the State and Federal level, and regulations were imposed before the Panel completed its evaluation. The Panel demonstrated that following the rapid dilution from moving cruise ships, the effluent data from the Summer of 2000 would not have exceeded water quality standards, and environmental effects were not expected.     

Total and labile metals in surface sediments of the tropical river-estuary system of Marabasco (Pacific coast of Mexico): Influence of an iron mine

Marabasco is a tropical river-estuary system comprising the Marabasco river and the Barra de Navidad Lagoon. The river is impacted by the Pe?a Colorada iron mine, which produces 3.5 million tons of pellets per year. Thirteen surface sediment samples were collected in May 2005 (dry season) in order to establish background levels of Al, Cd, Co, Cu, Fe, Ni, Pb, and Zn in the system and to ascertain the potential mobility of metals in the sediments. Analyses were carried out in the fraction finer than 63 microm, and labile metals extracted according the BCR procedure. Certified reference materials were used for validation of methods. Total concentrations of Cd, Co, Cu, Ni, Pb, and Zn were in the range of 0.05-0.34, 6-95, 0.7-31, 9-26, 2-18, and 53-179 mgkg(-1), respectively; Al and Fe ranges of 24-127, and 26-69 mgg(-1) correspondingly. Cadmium was found to be significantly labile in the sediments (20-100%), followed by Co (0-35%), Ni (3-16%) and Zn (0-25%), whereas the labile fraction for Cu, Fe and Pb was almost negligible (<4%). According with the total metal concentrations, background levels and normalised enrichment factors (NEF) of the metals studied, the impact of the Pe?a Colorada iron mine on the Marabasco system is lower than expected when compared with other similar World systems influenced by mining activities.     

Compound response of marine and terrestrial ecosystems to varying climate: pre-anthropogenic perspective from bivalve shell growth increments and tree-rings

Annual growth increments were examined from shells of the ocean quahog (Arctica islandica L.) from northwest Norway and from tree-ring samples of the Scots pine (Pinus sylvestris L.) from nearby coastal areas. The reconstructed annual growth increments were used to compare growth variability in marine and terrestrial ecosystems. Spatiotemporal comparison of the growth records showed statistically significant correlation during the 19th century A.D., indicative of ecosystem-independent response to pre-anthropogenic climate variations. Geographical correlation between marine and terrestrial records was only observed at the local scale. Years with particularly low winter or high summer North Atlantic Oscillation (NAO) indices showed the best synchronization of marine and terrestrial growth. Despite strong correlation during historical time, our palaeoecological evidence suggests that marine and terrestrial ecosystems may show dissimilar growth reaction to recently observed positive winter-NAO phases.