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.     

Abnormal development of Dentalium due to the Amoco Cadiz oil spill

A comparison was made between the development of Dentalium eggs, spawned by animals, collected before and after the Amoco Cadiz oil spill. Development of eggs from animals collected before the oil spill was significantly better than development of eggs from animals collected after the oil spill. It is suggested that development is affected by oil hydrocarbons, accumulated during oogenesis in the lipidrich phases of the oocytes.     

Minimal incorporation of Deepwater Horizon oil by estuarine filter feeders

Natural abundance carbon isotope analyses are sensitive tracers for fates and use of oil in aquatic environments. Use of oil carbon in estuarine food webs should lead to isotope values approaching those of oil itself, −27‰ for stable carbon isotopes reflecting oil origins and −1000‰ for carbon-14 reflecting oil age. To test for transfer of oil from the 2010 Deepwater Horizon spill into estuarine food webs, filter-feeding barnacles (Balanus sp.) and marsh mussels (Geukensia demissa) were collected from Louisiana estuaries near the site of the oil spill. Carbon-14 analyses of these animals from open waters and oiled marshes showed that oil use was <1% and near detection limits estimated at 0.3% oil incorporation. Respiration studies showed no evidence for enhanced microbial activity in bay waters. Results are consistent with low dietary impacts of oil for filter feeders and little overall impact on respiration in the productive Louisiana estuarine systems.     

Survival of sea anemones in Bunker C fuel

Sea anemones (Anthopleura elegantissima) can withstand submersion in Bunker C fuel oil for up to 1 h without visible adverse effects. The wet, mucus-covered tissues of the sea anemones may repel oil. During recovery, the sea anemones expand the column, evert the tentacles and reattach. A dahlia anemone (Tealia lofotensis) withstood immersion in oil for 15 min. The ability to withstand immersion in oil may confer an ecological advantage to sea anemones in contaminated areas.     

A case study of in situ oil contamination in a mangrove swamp (Rio De Janeiro, Brazil)

Mangroves are sensitive ecosystems of prominent ecological value that lamentably have lost much of their areas across the world. The vulnerability of mangroves grown in proximity to cities requires the development of new technologies for the remediation of acute oil spills and chronic contaminations. Studies on oil remediation are usually performed with in vitro microcosms whereas in situ experiments are rare. The aim of this work was to evaluate oil degradation on mangrove ecosystems using in situ microcosms seeded with an indigenous hydrocarbonoclastic bacterial consortium (HBC). Although the potential degradation of oil through HBC has been reported, their seeding directly on the sediment did not stimulate oil degradation during the experimental period. This is probably due to the availability of carbon sources that are easier to degrade than petroleum hydrocarbons. Our results emphasize the fragility of mangrove ecosystems during accidental oil spills and also the need for more efficient technologies for their remediation.     

Effect of oils on cell membrane permeability in Fucus serratus and Laminaria digitata

Leakage of electrolytes from discs of treated fronds of Laminaria digitata and Fucus serratus was the criterion used to study the effect of oils over 24 h on cell membrane permeability. Motor fuel oil increased cell membrane permeability in both algae at 1 h, or longer, after treatment. Laminaria changed to a green colour after 3 h, but Fucus was unaffected visibly by the oil. White spirit, diesel oil, or aviation fuel did not alter cell membrane permeability or visibly affect either alga over 24 h.     

Oil pollution and seabirds: Atlantic Canada 1976–1977 and some implications for northern environments

Chemical analyses of the oils on dead or moribund seabirds from Atlantic Canada during the winter of 1976–1977 indicated that some of the birds were contaminated with oil spilled by the Argo Merchant grounding, some by oil probably from the Grand Zenith sinking, and still others by oil from various small local spills of unknown origin. These victims demonstrated that an extremely minute oiling may lead to the death of a seabird when the effects of the oil are synergistically combined with the stresses imposed by severe environmental conditions. This may intensify the impact of oil in the Arctic and thereby have a profound effect on seabird populations.     

Temporal variation of chlorophyll a concentration in the coastal waters affected by the Hebei Spirit oil spill in the West Sea of Korea

Time series changes in chlorophyll a concentration before and after the Hebei Spirit oil spill that occurred in December 2007 were analyzed using NCEP wind and SeaWiFS/MODIS ocean color data. Prevailing southwesterly winds and northeast/southwestward tidal currents pushed the oil towards Korea’s West Sea coast of Taean. After the oil spill, daily chlorophyll a concentration decreased about 45-50% compared to the normal condition before the oil spill, and this decrease continued for about two weeks. Monthly mean chlorophyll a concentration in December 2007 was lower compared to the average value for the same month between 1998 and 2007, but, in October and November 2007 before the spill and in January-February 2008 after the spill, the concentration value was higher than average for the same period between 1998 and 2007.     

The Antonio Gramsci oil spill Impact on the littoral and benthic ecosystems

On 27 February 1979 the tanker Antonio Gramsci grounded off Ventspils (USSR) in the Baltic Sea. Some 5000–6000 t of crude oil were spilled, and drifted towards the archipelago of Stockholm (Sweden) and Åland (Finland). About 500 t oil was mechanically recovered in the Åland area. The effects of the oil on the littoral communities were studied for two months after the spill, and for the benthic community the long-term changes were recorded for three years. The immediate effects were small in the uppermost littoral (the Cladophora belt), but in the lower littoral (the Fucus belt) severe effects were recorded. Meiofaunal densities decreased in crustacean and mollusc species, but remained stable for the total community. Macrofaunal long-term changes could not be linked to the oil spill. Thus the effects of the oil were rather small, although a large area was contaminated.     

Effects of surface and sunken crude oil on the behaviour of a sea urchin

Studies have been made of the effects of exposure to various forms of crude oil on the righting behaviour of Paracentrotus lividus and its reactions towards the presence of oil. Prolongation of the righting response was recorded in animals exposed to contact with surface or sunken fresh crude oil or to their water soluble fractions. No such effect was recorded on exposure to weathered oils and results indicate that the more volatile components of crude oil were responsible for this effect. Paracentrotus showed no avoidance reaction to the presence of sunken oil in its vicinity. The likely ecological significance of these results is discussed.     

Application of entropy analysis of in situ droplet-size spectra in evaluation of oil chemical dispersion efficacy

In situ droplet-size distributions were measured using a laser in situ scattering and transmissiometry (LISST-100X) particle size analyzer during the evaluation of natural and chemical dispersion efficiency of crude oils under different wave and current conditions. An entropy grouping of the in situ dispersed oil droplet-size spectra has classified the multi-modal droplet-size distributions into different groups based on similar droplet-size spectra characteristics within groups and distinction between groups. A generalized linear logistic regression model was fitted to analyze the effects of a number of factors and their interactions on the grouping of oil droplet-size spectra. The grouped results corresponded to the oil dispersion efficiency at different levels. This new method for droplet-size distribution data analysis can have significant implication in field evaluation of natural and chemical dispersion efficiency of 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.     

Plasmid incidence in marine bacteria isolated from petroleum polluted sites on different petroleum hydrocarbons

Oil-degrading bacteria isolated from oil spills, an industrial bay, and an offshore oil field by liquid enrichment on crude oils and polynuclear aromatic hydrocarbon compounds were screened for extra-chromosomal DNA. Plasmids were detected in 21% of the strains isolated on whole crude oil and in 17% of the strains isolated on polynuclear aromatic hydrocarbons. Multiple plasmids were observed in 50% of the plasmid-containing strains. Pseudomonas was the predominant genus isolated during the study. Plasmids do not appear to be of importance to these strains during degradation of freshly introduced oil at a nonpolluted site such as might be the case in an ocean oil spill. Plasmids do appear to be significant in the adaptation of Pseudomonas species to chronic petroleum pollution.     

Monitoring oil spill bioremediation using marsh foraminifera as indicators

A controlled experiment was conducted in June 2000 to identify the environmental impacts of weathered crude oil on an Atlantic coastal salt marsh to help evaluate in situ biological remediation techniques for restoring the environment. Foraminifera, marsh microfossils known to be sensitive to a range of environmental stress factors, were used to monitor the effects of the residual oil and the experimental treatments. Results show that the foraminifera responded quickly to the oil and that the oil had a statistically significant, negative impact, as demonstrated by a dramatic increase in deformities in the tests of Miliammina fusca, compared to specimens from the non-oiled control plots. The results clearly show that foraminifera can be excellent indicators of oil pollution using only the percent of deformed tests. The advantages that foraminifera provide are the ease of sampling, processing and examination, with the added benefit that these organisms leave a fossil record.     

Impaired osmoregulation in the shrimp Palaemon adspersus exposed to crude oil extract

Palaemon adspersus is a hyper- and hypo-osmoregulating shallow-water shrimp. For a maximum period of 34 days P. adspersus were exposed to 20, 70, 100 and 200 ppb WSF of North Sea crude oil. The osmotic concentration of the haemolymph was measured by freezing point depression once a week. The ability to maintain hyper-osmolality was significantly decreased (p<0.05) after one, two and three weeks exposure to 200, 70 and 100 ppb, respectively. No effect was observed in 20 ppb. After an accidental exposure of shrimps to 24 h acute oil pollution, they were placed in pure sea water. The ability to maintain hyper-osmolality was reduced one week after the accidental oil exposure, but was regained within three weeks.     

Degradation of crude oil in a contaminated tidal flat area and the resilience of bacterial community

Crude oil spills, Hebei Spirit in South Korea, is considered as one of the worst environmental disasters of the region. Our understanding on activation of oil-degrading bacteria and resilience of microbial community in oil contaminated sites are limited due to scarcity of such event. In the present study, tidal flat sediment contaminated by the oil spill were investigated for duration of 13 months to identify temporal change in microbial community and functional genes responsible for PAH-degradation. The results showed predominance of previously known oil-degrading genera, such as Cycloclasticus, Alcanivorax, and Thalassolituus, displaying significant increase within first four months of the accident. The disturbance caused by the oil spill altered the microbial community and its functional structures, but they were almost restored to the original state after 13 months. Present study demonstrated high detoxification capacity of indigenous bacterial populations in the tidal flat sediments and its resilience of microbial community.     

Expansion of an invasive coral species over Abrolhos Bank,Southwestern Atlantic

Invasive coral species of the genus Tubastraea have been increasingly recorded in Southwestern Atlantic waters since the 1980s. Their invasion and infestation are mainly related to port and oil exploration activities. For the first time the presence of Tubastraea tagusensis colonies is reported in Espírito Santo State, colonizing a port shore area, and incrusting oil/gas platform structures situated in the southern Abrolhos Bank, which is part of the most important coral reef system of the South Atlantic Ocean. Tubastraea colonies exhibit fast growth and high recruitment rates, and colonized 40% of the analyzed structures in just four years. The projection of port and oil/gas industry growth for the Espírito Santo State (more than 300%) highlights an alert to the dispersal of this alien species to natural areas.     

Structure of residual oil as a function of wettability using pore-network modelling

In the water flooding of mixed-wet porous media, oil may drain down to relatively low residual oil saturations (S_or). Various studies have indicated that such low saturations can only be reached when oil layers in pore corners are included in the pore-scale modelling. These processes within a macroscopic porous medium can be modelled at the pore-scale by incorporating the fundamental physics of capillary dominated displacement within idealised pore network models. Recently, the authors have developed thermodynamic criteria for oil layer existence in pores with non-uniform wettability which takes as input geometrically and topologically representative networks, to calculate realistic S_or values for mixed-wet and oil-wet sandstones [16, 21]. This previous work is developed in this paper to include (i) the visualisation of the 3D structure of this residual oil, and (ii) a statistical analysis of this “residual/remaining” oil. Both the visualisation and the statistical analysis are done under a wide range of wettability conditions, which is reported for the first time in this paper.The structure of residual oil for strongly water wet systems is well known (where residual = remaining oil) and our model agrees with this but this structure changes radically for mixed wet systems (where residual ≠ remaining) and this has not yet been visualised experimentally. We find that for more water-wet systems high final residual oil saturations are reached at relatively small amounts of water injected and this oil is present in the pores as bulk oil. On the other hand, for more oil-wet systems we find a slow decrease of the amount of remaining oil with increasing amounts of injected water. During the process, the remaining connectivity of the oil phase is increasingly provided by oil layers only, hence the slow drainage. The final residual oil saturation, only reached in the theoretical limit of an infinite amount of injected water, is almost entirely contained in large number of (relatively low volume) oil layers, which are present in pores of most radius sizes.     

Effects on hatching in Littorina littorea after an oil spill

One year after an accidental spill of approx. 2000 t of Iranian crude oil on the west coast of Norway, specimens of the gastropod Littorina littorea were collected from the oil polluted shore and allowed to spawn in the laboratory. Snails were also collected from an unpolluted reference site. The oil contamination seemed to have no detectable effects on fertilization. However, the hatching success of the veliger larvae was significally less in the ‘oil polluted’ population. Some highly abnormal eggs were also observed in this egg population.     

Some ecological effects of the Venpet-Venoil collision

The effects of oil, released after the Venpet-Venoil collision in December 1977, on the intertidal fauna along the South Coast of South Africa have been monitored at monthly intervals since the incident. Localized areas, such as estuaries and sheltered coves, suffered the greatest damage due to the smothering effects of the oil. Damage to the remaining areas has been slight owing to the patchy distribution of the oil together with its physical and chemical characteristics.