An investigation was carried out into the PAH chemical contamination resulting from the “Erika” tanker fuel spillage of December 1999 along the French coast of the Bay of Biscay. A qualitative and quantitative assessment was conducted of this contamination in water, suspended particulate matter, sediments, and in intertidal molluscs. The chemical composition of PAHs in pre-spill and post-spill samples was determined and used to distinguish the “Erika's” fuel as the source of PAHs in the coastal environment of the Bay of Biscay. Changes in concentrations of PAHs were also assessed. The GC-MS analysis made it possible to identify and quantify parent unsubstituted PAHs, alkyl-substituted PAHs (C-PAH) and sulfur heterocycle unsubstituted and alkyl substituted compounds (SPAH and C-SPAH). The results of this study demonstrated that heavily oil-contaminated shorelines, including beaches, rocky coasts as well as sandy sediments apparently became reservoirs of spilled fuel and these continued to contaminate seawater, suspended particulate matter and mussels with PAHs. These conclusions were borne out by the following observations: (1) the pattern changes in PAH composition after the “Erika” oil spill were consistent in all contaminated compartments (water, suspended particulate matter SPM, intertidal sediments and molluscs), (2) the compositional patterns of PAHs after the “Erika” oil spill in contaminated water, SPM, intertidal sediments and molluscs constantly included alkyl-substituted phenanthrenes, pyrenes, chrysenes and sulfur heterocycle compounds in higher relative abundances than those in the pre-spill samples of these compartments, (3) the relative abundances of different suites of PAHs at contaminated sites were similar to those of weathered “Erika” fuel, (4) consistent and visible temporal decline in concentrations for water, SPM and molluscs, (5) the geographical contiguity of the stations with high concentrations of PAHs in molluscs matched the extent of the shoreline contamination by the spilled fuel. The increase in the contamination levels before and after the spill, together with the significant change in the pattern of PAH composition provide evidence of the intense and long-term chemical contamination of the “Erika's” fuel and of the damage to natural marine resources resulting from such contamination by toxic oil components.

Since March 2001, samples of the remaining oil from the wreck of the “Erika” have been collected along the Atlantic coastline in order to assess the natural degradation rate. Four years after the sinking of the tanker, chemical analyses of the oil revealed the influence of environmental parameters on the degradation kinetics. Among the diverse parameters controlling the fate of oil in the environment, biodegradation by microorganisms is known to play an important role. To investigate the role of microorganisms on “Erika” oil degradation, microbial mats from the Guérande salt marches were maintained in slurries containing the pollutant. From these slurries experiments, a low biodegradation rate of the “Erika” oil was detected indicating the degradation capacities of microbial mats. Biodiversity studies were conducted to further understand the biodegradation processes. Microbial mats from the Guérande salterns were maintained in microcosms to evaluate the impact of “Erika” oil on bacterial communities. Molecular analysis based on 16S rRNA and pufM encoding genes allowed fingerprinting of the bacterial and purple anoxygenic bacterial (PAB) communities respectively. These studies revealed bacterial diversity and communities changes showing the adaptation of microorganisms to the “Erika”.

To better understand the molecular mechanisms involved in the biodegradation of hydrocarbon compounds from the “Erika” oil-spill, we have studied the ability of Marinobacter hydrocarbonoclasticus strain sp 17 to cope with hexadecane as sole carbon and energy source. Growth kinetics of cultures shifted from acetate to hexadecane revealed the presence of a 20 hours adaptation phase. Changes in global protein expression in response to hexadecane was analyzed by two-dimensional gel electrophoresis. Of the 370 proteins detected 42 had their expression level altered in presence of hexadecane indicating that alkane adaptation may involve many cellular functions.

Levels of nickel and vanadium, trace metals found in high concentration in the oil spilled from the “Erika” tanker off Brittany (France) in December 1999 (41 ± 1 and 87 ± 3 mg kg−1 respectively), have been monitored over a one-year period following this accidental event in several benthic invertebrates. Ni and V in mussels (Mytilus edulis) and oysters (Crassostrea gigas) soft tissues were analysed twice a month by graphite furnace atomic absorption spectrometry and a scallop (Pecten maximus) shell daily growth bands were sampled every three bands by laser ablation and analysed by ICP-MS for these two contaminants. Survey data for mollusc tissues were compared with reference data arising from the national monitoring database. Ni concentrations in dried tissues, comparable with reference data (1.8 ± 0.9 µg g−1 in mussels and 1.2 ± 0.5 µg g−1 in oysters) do not show any additional input during the whole period. Conversely, a sharp increase in vanadium concentrations (up to 4.6 and 3.2 µg g−1 for mussels and oysters respectively) is observed around May 2000, i.e. 5 months after the wreck, compared with the monitoring data (1.4 ± 0.6 µg g−1 in mussels and 1.3 ± 0.6 µg g−1 in oysters). Furthermore, no Ni peak is detectable in the time profiles of scallop shell growth bands where a V peak is observed also in May 2000. This study shows that although a “mussel-watch-type” network, based on the monitoring of vanadium concentration in mollusc tissues, is able to identify contamination due to oil spills, similar information might be obtained a posteriori by analysing daily growth bands of scallop shells.

The petroleum spilt by the tanker “Erika” contained environmentally high concentrations of nickel (45 mg kg−1) and vanadium (83 mg kg−1). Our aim was to show that nickel and vanadium concentrations in marine organisms could be used as tracers of their exposure to oil deposits along the coast. Two biomarkers were determined, condition index (CI) and metallothionein levels. Samples were collected monthly from January to May 2000 from five sites along the coast of Vendée and Loire Atlantique: (1) Lérat, (2) La Govelle, (3) Saint Gildas, (4) La Bernerie and (5) La Fosse. Among benthic invertebrates, mussels Mytilus edulis (filter-feeders), periwinkles Littorina littorea (grazing-feeders) and dogwhelks Nucella lapillus (carnivora, bivalve predators) were selected. In addition, mussels were collected from a control site, Fier d'Ars (Ré Island). The species chosen as bioindicators have responded to the presence of oil in their environment by accumulating nickel and vanadium. The bioaccumulation of vanadium occurred early one month after oil spill whereas nickel bioaccumulation was deferred, probably as a consequence of a lower stability of vanadylporphyrins compared to nickelporphyrins which are known in particular for their role in stabilizing emulsions (film at the water/oil interface). Interspecific differences may be explained by different food habits: periwinkles grazed contaminated algae; mussels as filter-feeders retained particles and colloids from the water column; dogwhelks fed on mussels. Spatio-temporal changes of nickel and vanadium concentrations may result from (i) the arrival of new oil slicks, (ii) the action of cleaning of the coasts contributing to the re-suspension of petroleum. In all of the three species, few changes of the CI were observed from site to site. CI variations were linked to sexual ripening in mussels. Mussels originating from the control site showed MT concentrations significantly lower than those in specimens from impacted sites. The highest MT concentrations were observed in January and February, and then a consistent decrease was registered in March and May. MT concentrations in periwinkles increased very significantly in March and May. An increase in MT concentrations was also shown at this period in dogwhelks. Depending on the species, positive correlations were shown between MT and nickel and/or vanadium concentrations.

Oil spills are an important source of PAHs in marine and coastal areas and comprise a short- and long-term threat for aquatic organisms. Some PAHs are known to be toxic, in particular mutagenic and/or carcinogenic, and their toxicological effects must be evaluated. Here, the impact of the “Erika” oil spill, which occurred at the end of 1999, was studied by combining chemical (PAH analyses) and toxicological approaches (biological effect assessment). “Erika” elutriates have been found to be more toxic than the elutriate obtained with a crude oil, Bal 250, inducing deleterious effects in Mytilus galloprovincialis and Crassostrea gigas embryos and in Isochrysis galbana algae. The embryotoxicity test in mussel is more sensitive than growth test in I. galbana. Naphthalenic compounds make up more than 95% of total PAHs quantified in elutriates. “Erika” elutriates are enriched with naphthalene, methyl-naphthalene, anthracene and higher-molecular-weight compounds. On the contrary, Bal 250 elutriate is characterized by the highest dibenzothiophene, methyl-dibenzothiophene and dimethyl-dibenzothiophene levels. Weathering does not highly affect the toxicity of the “Erika” oil. This study also confirms the potential impact of the “Erika” fuel on the biological quality of sea water and sediments from Traict du Croisic on the Atlantic coast of France.

Immunological alterations may be used as ecotoxicological biomarkers to detect and monitor biological effects of chemical contaminants in polluted environments. This study reports on a survey of Pacific oysters from the Atlantic coast of Britanny (France) after the “Erika” oil spill. Reared stocks were sampled twice a year from November 2001 to March 2003 at three impacted sites and at an additional site outside the spill area. A multiparametric diagnosis of the immune system was performed on individual hemolymph samples to identify structural, immunopathological alterations and functional impairment of immunocompetent cells. One year after the spill, severe immunological alterations were observed in a site heavily impacted by oil. Since the oysters there had higher contents of PAH compared to the other sites, it was suggested that chronic contamination, possibly generated by oil trapped in the sediments, had induced immunotoxicity. Moreover, moderate variations in some hemolymph parameters observed at the non-impacted area strongly suggested that natural environmental factors may have generated physiological stress. An immunotoxicological index applied here in order to integrate all measurements of defense-related functions appeared to be an efficient tool to identify samples suffering immunological stress.

The transfer of polycyclic aromatic hydrocarbons (PAHs) from bivalves, through the food chain to vertebrates was of concern. Our research aimed at estimating potential effects for consumers resulting from the ingestion of seafood contaminated by oil spill pollutants. After the “Erika” wreck, mussels (Mytilus sp.) were collected from sites of the Atlantic coast impacted to various degrees by the oil slick and constituted contaminated food for rats during 2 and 4 weeks. Genotoxic damage were studied in rats by means of COMET assay carried out in liver, bone marrow and peripheral blood. Biochemical and genomic effects such as the induction of CYP 1A1 and the expression of cytochrome genes were measured in rat livers. The most sensitive biological parameter reflecting the transfer of contaminants via the food appeared to be DNA breaks studied by means of the COMET assay. Genotoxic damage, observed mainly in the liver, were rather moderate and remained not persistent. This study underlined the bioavailability of pollutants in fuel oil contaminated mussels for consumers, and the complexity of the contamination consecutive to the oil spill. The occurrence of related PAH compounds in addition to non-substituted PAHs in fuel oils and mussels raised the question of their implication in the registered effects.

A 3-year survey was made of several biological markers in mussels (Mytilus edulis) exposed in situ to the oil that came ashore after the wreck of the “Erika” tanker on the Brittany (France) coast in December 1999. The mussel response was assessed using a set of 7 biomarkers, most of them related to the metabolism of organic contaminants. After a series of validation tests, data was evaluated for only 5 biomarkers: acetylcholinesterase (AChE), glutathione S-transferase (GST), catalase (CAT), malondialdehyde (MDA) and deoxyribonucleic acid (DNA) adducts. No significant reductions in GST or CAT levels were observed, levels of DNA adducts and MDA were high during the 6 months immediately following the accident and levels of AChE were significantly lower during the first year of the survey suggesting a general stress. A simple multivariate graphic method, the integrated biomarker response index, was used to combine 4 of the 5 validated biomarkers and quantify the degree of impact on mussels at different sites. The results show that mussel populations were affected by the oil spill only during the first year after the event.

Benthic foraminifera are used as potential bio-indicators of pollution due to the “Erika” oil spill. The foraminiferal assemblages from a site situated on the tidal mudflat of the southern Bay of Bourgneuf (Vendée, France) have been sampled 19 times on a monthly/bimonthly scale. The field study reveals uncommon low densities and poor faunas in the first 21 months of the survey. In order to understand the effect of the “Erika” fuel, foraminiferal cultures with 0 to 72.0 mg per 100 ml of “Erika” oil were maintained in controlled conditions in the laboratory. In the laboratory, an experiment with 5.5 mg per 100 ml of oil shows morphological abnormalities, cellular modifications and a low rate of reproduction. These first results confirm the potential toxicity of the fuel No. 2 from “Erika” and the sensitivity of foraminifera to this pollutant.

The impact of the “Erika” oil spill on the tidal rock pool community, and particularly on two species of sea urchin (Paracentrotus lividus and Psammechinus miliaris), was investigated over a 3-year period, at Piriac-sur-Mer (Department of Loire-Atlantique, France, 47°21.6' N; 2°31.7' W). A dramatic increase in the abundance of two macroalgae Ulva sp. and Grateloupia doryphora occurred following a 100% mortality of sea urchins observed three weeks after the oil spill. The density of sea urchins and of other main herbivores, the periwinkle Littorina littorea and the trochid mollusks Gibbula umbilicalis and Gibbula pennantii, were monitored between January 2000 and March 2003. There was significant inverse relationship between the overall density of herbivores (sea urchins, periwinkles and trochid mollusks) and the percent cover of algae in the tidal pools. The first urchins in the tidal pools were observed two years after the oil spill and it took three years to reach sea urchin densities comparable to the reference value of 63 ind.m−2 obtained before the oil spill.

An analytical method consisting in enzymatic deconjugation, solid phase extraction and purification, and gas chromatography/mass spectrometry analysis after derivatization was used in this study to quantify Polycyclic Aromatic Hydrocarbon (PAH) metabolites in the bile of fish. The method has been applied in a laboratory experiment studying the fate of pyrene in basin containing soles. This study has allowed the identification of 1-hydroxypyrene as the single metabolite in bile after enzymatic deconjugation. In a second time, 1-hydroxypyrene has been used as a biomarker of exposure in the case of the “Erika” oil spill. This biomonitoring was successful in demonstrating the exposure of juvenile soles to PAHs present in the “Erika” fuel oil.

Evaluating the ecological impact of an oil spill is a complex issue requiring coherently articulated examination of the sequence of interactions that link the cell, where contaminants exert their effects, to the ecosystem, where interactions with human activities arise. This sequence of interactions traverses the frontiers between scientific disciplines (chemistry, toxicology, physiology, and fisheries ecology). Using the common sole (Solea solea L.) as a model species for the coastal habitats polluted by the “Erika” oil spill, our research project attempted to define indices of functional integrity that characterised the consequences of fuel exposure at the different biological levels. The coupling of field observations with experimental laboratory work revealed how functional alterations which are readily observable within individuals and their organs are progressively obscured as investigation progresses towards more complex organisational levels. Some of the approaches and indices are proposed as instruments for evaluating the impact of contamination by hydrocarbons.

The “Erika” oil spill has killed more seabirds than any before in Europe: nearly 70 000 guillemots (Uria aalge) were found dead or alive on beaches, and many more are thought to have been killed. This unexpectedly high number highlighted how poor our knowledge was on spatial and temporal patterns in seabird distribution in the Bay of Biscay. The purpose of our research project, “ERIKA-Avion”, was to fill this gap, providing the first distribution maps and abundance estimates of seabirds wintering in the entire shelf of the Bay of Biscay. In particular, we analysed fine-grained distribution maps for the wintering auks, comparing their areas of highest density with the oil drift area, and proposing for the first time (although preliminarily) minimal abundance estimates for these birds in this area.

We investigated the impact of the “Erika” oil spill in the Bay of Biscay (France) on seabird populations. Relative abundance and spatial distribution at sea between 1980-1999 and 2000-2002 periods were compared. This study took place in a standardized monitoring at sea carried out with Coast Guard vessels following the line transect method. This work rests on 107 551 standardized counts of one minute before “Erika” and 23 449 after the oil spill. There was not a simple correlation between the number of individuals found oiled and the numerical variation of the populations at sea during the two years following the accident. The guillemot Uria aalge, the most frequently collected species in the north of the Bay of Biscay, showed no decrease in at sea abundance during the two years following the pollution. Conversely, some species found in small numbers on the coast (e.g. divers Gavia sp., razorbill Alca torda, common scoter Melanitta nigra) decreased significantly at sea (20 to 80%). Overall, marine bird populations declined significantly in the northern sector of the Bay of Biscay (48°32' to 46°58' north) and increased in the southern sector (45°13' to 43°15' north), whereas decreases and increases occurred in the central sector (46°57' to 45°14' north). Changes in the spatial distribution of the species after the “Erika” oil spill occurred through disappearance or retraction (Bay of Vilaine, Houat-Hoedic archipelago), or through displacement and reinforcement (Gouf of Capbreton). Overall, this suggests a redistribution of the populations within the Bay of Biscay, depending on the level of injuries to the ecosystems caused by the pollution.

Between 80 000 and 150 000 marine birds wintering in the Bay of Biscay were killed during the “Erika” oil spill. Three complementary studies were conducted to investigate the geographic origins of these birds. The common guillemot, Uria aalge, represented more than 80% of the oiled birds and these studies thus focused primarily on this species. Analyses of 184 ring recoveries and biometry of 1851 corpses indicated that guillemots originated from a large geographic area, including colonies from across the British Isles and the North Sea, along with more northern localities. However, the majority of individuals came from colonies located between western Scotland and the Celtic Sea. The third study, based on a population genetic approach using microsatellite markers (samples from dead oiled birds and from more than 600 birds caught in 19 breeding colonies), showed little genetic differentiation among north-eastern Atlantic guillemot colonies. This result limits the ability to identify the geographic origins of the birds using only DNA samples, but reveals a significant amount of gene flow among colonies. Overall, results indicate the large spatial scale of the oil spill's impact and underline the usefulness of combining multiple approaches to assess the local and regional effects of such accidents.

Oil spills can have direct effects on organisms (mortality or morbidity), indirect effects (through alteration of lower trophic levels) or be associated to exposure to trace elements contained in oil (markers). An effect of the “Erika” oil spill was investigated by spatio-temporally comparing mortality, population structures, diets and concentrations of vanadium, nickel and porphyrines in small delphinids, seals and otters from the French Atlantic coasts. These species might differ in their vulnerability to oil. Changes in mortality and its demographic structures were within previously observed ranges. The diet of the common dolphin showed an extended period of high inter-individual variability in the year 2000. Vanadium concentrations in delphinids were chronically high, but did not increase significantly after the oil spill. Porphyrins concentrations in seals and otters were low suggesting a limited exposure to contaminants, but the ratio between proto- and copro-porphyrins in otter spraints from oiled vs. unoiled sites varied significantly. No measurable effect of the “Erika” oil spill was found in dolphins and seals.