Shallow sublittoral meiofauna communities and sediment polycyclic aromatic hydrocarbons (PAHs) content on the Galician coast (NW Spain), six months after the Prestige oil spill

The aim of this work was to detect the impact of Prestige oil spill on meiobenthic community structure at higher levels of taxonomic aggregation. In addition, the relationship between sediment individual polycyclic aromatic hydrocarbon (PAH) concentration and meiofauna community structure was investigated. Six months after the Prestige oil spill, meiobenthos community and sediment PAHs content from seven shallow subtidal localities along the Galician coast were studied. Two sites presented differences in community structure, characterized by high densities of nematodes, gastrotrichs and turbellarians, and low densities of copepods. Chrysene and triphenylene were only found at these two disturbed sites and could be responsible for differences of meiobenthos community structure. However, differences in community structure of sites could be linked with sedimentary parameters, and discrimination between the effect of PAHs and sedimentary parameters was impossible due to the lack of baseline studies on meiobenthos and PAHs contents in this area.     

Impact of Amoco Cadiz oil spill on intertidal and sublittoral meiofauna

Changes of meiofauna densities (nematodes and harpacticoid copepods) were studied in intertidal and sublittoral fine sand heavily polluted by the Amoco Cadiz oil spill. A general decrease in the nematode abundance was obvious in intertidal sand seven months after the pollution in spite of the occurrence of the natural spring bloom. No changes in the nematode and copepod densities could be detected in sublittoral sand. Comparisons with the pre-pollution data show, however, a significant decrease in the nematode diversity, mainly due to the increase of some limited dominant species after pollution.     

Observations on the biota of an estuarine beach at Hardys Bay (NSW, Australia) following a spillage of aldrin

An industrial accident resulted in a spillage of aldrin onto an estuarine beach at Hardys Bay, New South Wales. Samples of water and sediment were taken 3 weeks later to measure the level of contamination resulting from the spill. The abundances of some intertidal biota were also determined at the site of the spillage and in other uncontaminated areas.

Three weeks after the spill, samples of water were not contaminated by aldrin but samples of sediment from the surface in the vicinity of the drain contained aldrin. In comparison to uncontaminated locations the abundances of crustacea were greatly reduced in the vicinity of the drain but abundances of polychaetes were not significantly different. The field data on the relative susceptibility of the two groups of animals agrees well with laboratory derived LC50 data for crustacea and polychaetes.

The study suggests that degree of contamination of water and sediment may not always be an accurate reflection of acute impact on biota, and that different components of the biota can show different reactions to the presence of a toxic chemical.     

Estimating and quantifying oil contamination on the shoreline

A wide range of parameters can be used to describe the degree of oil contamination on the shoreline following a spill. This study compares five parameters, obtained by visual estimates and systematic ground mapping on a gravel beach at an experimental spill site. For shoreline cleanup decisions the most relevant parameter involves the measurement of the area of surface oil cover and calculation of the volume of contaminated sediments. Accurate estimates of the volume of oil on the shore require sampling and measurements of the concentrations of oil in the sediments. The reliability of aerial or ground estimates of the oil distribution on a gravel beach decreases with time as the colour of the surface oil changes to blend with the local sediments.     

The Eurobulker oil spill: mid-term changes of some ecosystem indicators

The sinking of the tanker Eurobulker in Southern Evoikos gulf (Aegean Sea, Greece) in September 2000 resulted in a spill of 700 tons of crude oil. The environmental impact of the spill was studied by the National Centre for Marine Research. The hydrocarbon concentrations in water, sediment and coastal benthic organisms were measured and the response of the benthic communities to the disturbance caused by the oil spill was studied along the direction to the coast and over three sampling seasons. The most severe and direct effects were evidenced on the muddy benthic communities of the accident site and the stations in the close vicinity sampled shortly after the spill. The effects included reduction of the species richness and community diversity, but the communities reached full recovery 8 months later. The impact of the spill was more indirect and delayed in the coastal stations, where as the hydrocarbon measurements indicated, the pollutants were transported later and induced their effects on the benthic communities 6 months after the accident.     

Main meiofauna taxa as an indicator for assessing the spatial and seasonal impact of fish farming

The present study aimed to establish potential indicators of fish farming pollution in muddy substrate, by means of meiofauna, and to test whether the effect of the fish farm is more important to determine the meiofauna community than the seasonal environmental conditions. Sampling was performed in spring, after several months of light feeding, and in summer, at high food supply. Samples were collected in three directions at various distances from the floating cages. Harpacticoid copepods and kinorhynchs, whose abundance decreased under the cages, were put forward as indicator taxa. However, harpacticoid copepods were sensitive to fish farm only, while kinorhynchs showed responsiveness to fish farm and to seasonal environmental conditions. Total meiofauna density was dependent on season sensu stricto. The nMDS clearly showed a ‘cage community’ and ‘control community’ in both sampling occasions; therefore it is a good tool for impact assessment.     

Behaviour of diesel fuel on a high energy beach

On 1 March 1984, a spill of diesel fuel and gasoline on the east coast of the Queen Charlotte Islands, Canada, resulted in significant contamination of the beach. Sediment and water samples analysed for oil concentration indicated that oil moved through the beach sediments in response to the tidal cycle and the subsequent changing water table levels. Concentrations tended to be low and variable in samples collected during a flood tide as the oil was driven through the sediments to the upper beach face. On the ebb, however, concentrations increased nearly five times as oil was released from the lowering water table onto the surface of the beach face. At low tide some residual oil remained trapped in the sediments, the amount correlating with the degree of sediment sorting (i.e. sediment porosity). In spite of high wave exposure, traces of fuel remained within 300 m of the spill site after 60 days. This suggests that light, unweathered oil is not mechanically abraded and dispersed in the same manner as more weathered oil; rather the light oil is released from the beach sediments principally during an ebbing tide, and wave action probably affects the cleaning of the beach in a minor capacity.     

Effects of water-soluble fractions of crude oil and dispersants on nitrate generation by sandy beach microfauna

Effects on sandy beach microfauna of soluble pollutants, such as might be associated with an oil spill, were investigated in terms of nitrate generation. Nitrate generation by the microfauna in small sand columns in the laboratory was severely inhibited by water-soluble fractions of crude oil, dispersant and oil/dispersant mixtures in order of increasing effects. Short-term effects of such pollutants on nutrient regeneration by exposed sandy beaches are discussed.     

Effects of oil spill on seawater infiltration and macrobenthic community in tidal flats

Tidal flat ecosystem simulators are used to clarify the effects of stranded fuel oil on tidal flat ecosystems. Results show that oil spills increase the periphyton on sediment by decreasing the predation stress caused by deposit feeders. About a month after an oil spill, the total population density of the macrobenthos recovered. The oxidation-reduction potential in the surface sediment drops to a negative value after the oil spill, and the anaerobic condition throughout the sediment seems to be responsible for the decrease in the population density of the macrobenthos. The infiltration volume of seawater into the oil-stranded sediment decreases to a third of that without the oil spill. The recovery of infiltration volume after about a month coincides with the recovery of the population density of the macrobenthos. This result suggests that the macrobenthic population is highly dependent on the infiltration of seawater.     

Medium-term assessment of the effects of the Prestige oil spill on estuarine benthic communities in Cantabria (Northern Spain, Bay of Biscay)

A specific monitoring program was implemented in the estuaries of Cantabria (northern Spain) in order to assess the medium-term effects (2003-2005) of the Prestige oil spill (POS) on benthic macroinvertebrate communities. A control-impact design was adopted, examining four unaffected and five oil-affected estuaries. High mortalities and significant differences in overall richness and diversity between the control and impacted estuaries were not detected. Some changes in the temporal evolution of species abundance were observed for some key species, but these could not be related to the spillage event. It was not possible to ensure that low magnitude effects had not occurred, due to the high range of natural variability of benthic communities, the confounding effects of other contamination sources and the absence of previous reference conditions.     

The Eleni V oil spill: Fate and effects of the oil over the first twelve months: Part II. Biological effects

The general effects of the Eleni V oil spill on fisheries and intertidal organisms are described. There appears to have been little damage except by direct smothering. Oil hydrocarbon concentrations have been followed in a small intertidal population of mussels (Mytilus edulis) at Corton beach. Although the area became visually clean of oil, hydrocarbon concentrations in mussel flesh remained high 12 months after the spill and depuration rates in the laboratory were very slow. Shrimps (Crangon crangon) exposed to a water extract of beached Eleni V oil for 42 days showed no ill effects and little uptake of hydrocarbons. At the North Harbour site, where beached oil has not been disturbed, it appears that the fauna, used to oil contamination from other sources, has been little affected by the additional Eleni V oil.     

The Eleni V oil spill: Fate and effects of the oil over the first twelve months: Part I. Oil in Waters and Sediments

The fate and effects of the spill of Eleni V heavy fuel oil in May 1978 have been followed at two sites; one a heavily-polluted area subject to mechanical clean-up and one an undisturbed site where oil remains. At the first site the mechanized clean-up, and re-sorting of beach material by winter storms, has left the area visually clean of oil. However, near-shore and interstitial waters still contain high concentrations of Eleni V hydrocarbons 12 months after the spill. At the undisturbed site there has been very little change in the appearance and chemical composition of the oil during this period.     

Quantitative analysis of residual fuel oil in sediment samples by absorption spectrophotometry

The ultraviolet spectra of samples of an oil pollutant and crude oil at various concentrations were examined. Strong absorption maxima appear at approximately 228 nm and 256 nm. These permit a quantitative analysis in polluted sediment samples many months after the spill. Results obtained from three visits to an oil polluted beach on the South coast of South Africa are reported.     

Impacts of a fuel oil spill on seagrass meadows in a subtropical port, Gladstone, Australia--the value of long-term marine habitat monitoring in high risk areas

We used an established seagrass monitoring programme to examine the short and longer-term impacts of an oil spill event on intertidal seagrass meadows. Results for potentially impacted seagrass areas were compared with existing monitoring data and with control seagrass meadows located outside of the oil spill area. Seagrass meadows were not significantly affected by the oil spill. Declines in seagrass biomass and area 1month post-spill were consistent between control and impact meadows. Eight months post-spill, seagrass density and area increased to be within historical ranges. The declines in seagrass meadows were likely attributable to natural seasonal variation and a combination of climatic and anthropogenic impacts. The lack of impact from the oil spill was due to several mitigating factors rather than a lack of toxic effects to seagrasses. The study demonstrates the value of long-term monitoring of critical habitats in high risk areas to effectively assess impacts.     

The effect of the "Prestige" oil spill on the plankton of the N-NW Spanish coast

Chlorophyll, primary production, zooplankton biomass and the species composition of phytoplankton and zooplankton were studied in 2003, after the Prestige shipwreck. The information obtained was compared to previous data series available for the area affected by the spill. A large data series on plankton variables for the N-NW Spanish coast existed, and therefore a realistic evaluation of the effects by comparison with the range of natural variability could be carried out. We emphasized the evaluation of impact during the spring bloom, the first important biological event after the spill. Some minor changes were observed occasionally, but they did not show any clear pattern and were more related to the natural variability of the ecosystem than to effect of the spill. Plankton community structure did not undergo any changes. Only a few species were more abundant during spring 2003 than in previous years. No significant changes were detected in the planktonic community during productive periods, such as the spring bloom and the summer blooms related to intrusions of East North Atlantic Central Waters. The lack of evidence of the effects of the spill on planktonic communities is discussed in terms of the characteristics of the fuel, the high dynamics of the water masses, the biological mechanisms through which the fuel from the surface waters is transferred to the sea floor and, particularly, the influence of the natural variability by means of large and meso-scale hydrographic processes in the area under study. At the present time it is not possible to determine any minor effects the spill may have had on the plankton owing to the great variability of the planktonic cycles and the short-term impact of the oil from the Prestige on the pelagic system.     

Effects of the 'Prestige' oil spill on macroalgal assemblages: large-scale comparison

An assessment of the effects of the 'Prestige' oil spill on intertidal, macroalgal assemblages was carried out comparing abundance data obtained before and after the spill. Four zones in the North and Northwest coast of Spain were sampled, one of them located at the immediate vicinity of the spill, the zone most heavily oiled. Macroalgal assemblages had similar structure between years. Neither critical decrease in abundance of the dominant macroalgae, nor increase in opportunistic species were found. Some differences in abundance were observed, but they did not show any pattern, being more likely the result of the natural variability of the assemblage. Extensive, but not intense fuel deposition on the shores and a limited use of aggressive cleanup methods are suggested as possible causes for the lack of the effects in these assemblages after the 'Prestige' oil spill.     

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.     

Preliminary study on responses of marine nematode community to crude oil contamination in intertidal zone of Bathing Beach, Dalian

This study investigated the responses of marine nematodes to crude oil contamination in polluted and relatively uncontaminated sites in Dalian Xingang, China, 40 days after an oil spill. Samples were taken at different tide levels on the beach and at different positions along the beach. We present the results of a comparison of nematode assemblages from undisturbed sediment from the Xiajiahezi Bathing Beach with those from sediment from the Xinghai Bathing Beach contaminated with crude oil. A total of 1666 nematodes from 26 genera were found in this study. Results showed significant differences in nematode assemblages between samples from undisturbed controls and those from the polluted area. Nematode abundance, number of species, diversity and species richness decreased significantly with increasing levels of crude oil contamination. Fifteen genera were eliminated and seemed to be composed of species intolerant to crude oil contamination; only the abundance of Marylynnia sp. increased slightly.     

Impacts of a fuel oil spill on seagrass meadows in a subtropical port,Gladstone, Australia – The value of long-term marine habitat monitoring in high risk areas

We used an established seagrass monitoring programme to examine the short and longer-term impacts of an oil spill event on intertidal seagrass meadows. Results for potentially impacted seagrass areas were compared with existing monitoring data and with control seagrass meadows located outside of the oil spill area.Seagrass meadows were not significantly affected by the oil spill. Declines in seagrass biomass and area 1 month post-spill were consistent between control and impact meadows. Eight months post-spill, seagrass density and area increased to be within historical ranges. The declines in seagrass meadows were likely attributable to natural seasonal variation and a combination of climatic and anthropogenic impacts. The lack of impact from the oil spill was due to several mitigating factors rather than a lack of toxic effects to seagrasses. The study demonstrates the value of long-term monitoring of critical habitats in high risk areas to effectively assess impacts.     

Hebei Spirit oil spill monitored on site by fluorometric detection of residual oil in coastal waters off Taean, Korea

The spatiotemporal distributions of dissolved and/or dispersed oil in seawater and pore water were monitored on site by fluorometric detection method after the Hebei Spirit oil spill. The oil concentrations in intertidal seawater, 15 days after the spill, were as high as 16,600 μg/L and appeared to decrease below the Korean marine water quality standard of 10 μg/L at most sites 10 months after the spill. Fluorometric detection of oil in pore water was introduced to eliminate the effects of grain size for the quantification of oil in sediments and to better explain spatial and temporal distribution of oil pollution at sandy beaches. The fluorescence detection method was compared with the conventional laboratory technique of total petroleum hydrocarbon analysis using gas chromatography. The method of fluorescence detection of oil was capable of generating results much faster and more cost-effectively than the traditional GC technique.