Effects of a Dispersed and Undispersed Crude Oil on Mangroves, Seagrasses and Corals

The primary objective of this study was to evaluate the application of dispersant to spilled oil as a means of reducing adverse environmental effects of oil spills in nearshore, tropical waters. The results of numerous laboratory and field studies have suggested that dispersants may play a useful role in reducing adverse impacts on sensitive and valued environments such as mangroves, seagrasses, and corals. However, the use of dispersants has not been allowed thus far in most situations because of a lack of direct experimental data on the various effects of dispersants and the environmental trade-offs presumed to occur as a result of their application to crude oils. To accomplish this objective, a 21/2- year field experiment was designed in which detailed, synoptic measurements and assessments were made of representative intertidal and nearshore subtidal habitats and organisms (man-groves, seagrass beds, and coral reefs) before, during, and after exposure to untreated crude oil and chemically dispersed oil. The results were in-tended to give guidance in minimizing the ecological impacts of oil spills through evaluation of trade-offs in the relative impacts of chemical dispersion to tropical marine intertidal and subtidal habitats

Modelling regional land change scenarios to assess land abandonment and reforestation dynamics in the Pyrenees (France)

International audienceOver the last decades and centuries, European mountain landscapes have experienced substantial transformations. Natural and anthropogenic LULC changes (land use and land cover changes), especially agro-pastoral activities, have directed influenced the spatial organization and composition of European mountain landscapes. For the past 60 years, natural reforestation has been occurring due to a decline in both agricultural production activities and rural population. Stakeholders, to better anticipate future changes, need spatially and temporally explicit models to identiy areas at risk of land change and possible abandonment. This paper presents an integrated approach combining forecasting scenarios and a LULC changes simulation model to assess where LULC changes may occur in the Pyrenees Mountains, based on historical LULC trands and a range of future socio-economic drivers. The proposed methodology considers local specificities of Pyrenan valleys, sub-regional climate and topographical properties, and regional economic policies. Results indicate that some regions are projected to face strong abandonment, regardless of scenario conditions. Overall, high rates of change are associated with administrative regions where land productivity is highly dependent on socio-economic drivers and climatic and environmental conditions limit intensive (agricultural and/or pastoral) production and profitability. The combination of the results for the four scenarios allows assessements of where encroachment (e.g. colonization by shrublands) and reforestation are the most probable. This assessment intends to provide insight into the potential future development of the Pyrenees to help identify areas that are the most sensitive to change and to guide decision makers to help their management decisions

Tropical Oil Pollution Investigations in Coastal Systems (TROPICS)

Research Planning Institute, Inc. (RPI) and Bermuda Biological Station for Research, Inc. (BBS) have implemented a long-term program of research on the fate and effects of oil spills and dispersants on coastal tropical areas. Tropical Oil Pollution Investigations in Coastal Systems (TROPICS) is an integrated study to allow examination of possible tradeoffs of impacts between intertidal and subtidal tropical ecosystems and to establish whether the application of dispersants to spilled oil in nearshore tropical areas is an ecologically safe means of minimizing damages to these habitats. Baseline studies have been conducted at selected field sites to characterize and measure biological, chemical, and physical parameters prior to experimental spills. The fate and effects of dispersed and undispersed oil in the nearshore tropical ecosystem are being monitored for one year after the experimental treatments. Detailed measurements are being made of the mangroves and sea grasses to determine effects on primary productivity, growth, general condition, and survival. Infauna and epifauna are being monitored to estimate changes in density and diversity, and motile macrofauna are being observed to determine changes in distribution and behavior. Corals are being measured to determine changes in growth, abundance, and coverage; and the infauna, epifauna, and resident fish communities are being monitored as well. The water column, sediments, and biota are being monitored chemically using discrete and flowthrough pumping techniques, largevolume extraction techniques, replicate sediment cores, and tissue samples of dominant biota. Samples are being analyzed using ultraviolet fluorometry (UV), gas chromatography (GC), and GC/mass spectrometry

The Effects of Crude Oil and Dispersed Crude Oil On Tropical Ecosystems: Long-Term Seagrass, Mangrove, and Coral Studies

Tropical ecosystems typically contain three sensitive and important habitats: seagrass beds, mangrove forests, and coral reefs. The effects of oil on these systems have been studied individually in the laboratory with few long-term studies on the ecosystem as a whole. Described in this report is an experiment carried out on the Caribbean coast of Panama (Bocas del Toro). Prudhoe Bay crude oil and dispersed crude oil were released on separate sites, each containing seagrass (Thalassia testudinum), mangrove (Rhizophora mangle), and coral habitats representative of ecosystems in Caribbean waters. The short-term (two-year) results of the study are presented along with those from the long-term (+10 year) re-assessment. The study was a simulation of the “worst case” exposure level for dispersed oiland a high exposure level for crude oil. The application of oil and dispersed oil was monitored regularly over a 23 hour period, the sites being monitored periodically over two years, and re-examined 10 years after the experiment. Assessments were made over time of the distribution and extent of contamination by hydrocarbons and the short- and long-term effects on survival, abundance, and growth of the dominant flora and fauna in each habitat. In the short term, chemically dispersed oil caused declines in the abundance of invertebrates, including corals, but the effects had essentially disappeared over the long term. Fresh, untreated oil had severe, long-term effects on survival of mangroves and associated fauna, but relatively minor effects on seagrasses, corals, and associated organisms. The results of this study provide definitive data through which decisions may be made about the use and non-use of chemical dispersants, while adding to the knowledge of hydrocarbon effects and fate in the ecosystems. The methods and results of this controlled field experiment also have implications for the effective design of microcosm and mesocosm toxicity studies

Preparing bilingual teachers on the U.S./Mexico border: including the voices of emergent bilinguals

Language policies in the U.S., including matters relating to bilingual education, are tangled up with political tensions and ideology. All too often, the dialogue among educators and policymakers about what constitutes best practices for people learning English – for whom we will use the term emergent bilinguals (EBs) (Garcia, Kleifgen and Falchi 2008) – fails to include the voices of those they serve. The Rio Grande Valley (RGV) of South Texas provides a uniquely valuable laboratory in which to study bilingual education because of its location, demographic makeup, and migration patterns. In this study, a pedagogical intervention was made with a cohort of teacher candidates studying at a university in South Texas; the participants had themselves experienced bilingual education, as children, in RGV public schools. The implications of this study can be extended to teacher preparation for other minority communities receiving majority language instruction. The analysis based on transcripts of focus group discussions and asynchronous online discussions among 26 teacher candidates, of Mexican origin or descent, applies LatCrit theory and illustrates the development of a critical awareness of the hegemonic forces impacting the linguistic development of EB students such as themselves