Effects of an oil spill in the northern Baltic

Oil pollution from the tanker Palva which ran aground in Finnish waters in 1969 provides an example of the hazards of oil spills in cold waters. The Palva incident and its aftermath were studied by Finnish biologists and some of their findings are reported here. The chief casualties were eider ducks, but fortunately long-term effects appear to have been small.     

Recovery of interior brackish marshes seven years after the chalk point oil spill

Seven years after the April 2000 spill of 140,000 gallons of a mixture of No. 6 and No. 2 fuel oils in the Patuxent River, Maryland, heavily oiled brackish marshes showed continuing effects. Stem density and stem height were significantly lower in oiled versus unoiled sites for Spartina alterniflora but not Spartina cynosuroides habitats. In contrast, belowground biomass was significantly lower in S. cynosuroides habitats but not S. alterniflora habitats. Total PAH concentrations were up to 453 mg/kg in surficial soils (0-10 cm) and 2921 mg/kg with depth (10-20 cm). The oil had lost 22-76% of its initial PAH content after seven years, although the oil in marsh soils has undergone little to no additional weathering since Fall 2000. Based on amphipod acute toxicity tests and sediment quality guidelines, 25% of the soils in the marsh are expected to be toxic (ESB-TU_FCV values > 3.0; P_Max > 0.65).     

First observations in a high rocky-shore community after the Erika oil spill (December 1999, Brittany,France)

The high mediolittoral rocky-shore community on the island of Groix (Brittany, France), was studied for the year immediately following the Erika oil spill (12/12/1999). The macrofaunal assemblages of three habitats (exposed bedrock, crevices, boulders) under three situations (non-impacted, impacted and not washed, impacted and washed) were monitored monthly. The assemblage of each habitat showed specific responses to the impacts and initiated various patterns of succession: the bed rock assemblage changed in terms of abundance but no species-richness variations occurred; in the crevices richness variations occurred both in the disappearance of some species and the immigration of opportunistic ones; the boulder assemblage lost many species and remained unstructured one year after the oil spill. These first results of this most recent oil spill in Europe, raised the question of the relative importance of habitat-species and species interactions on the community structure.     

The West Falmouth oil spill after 20 years: Fate of fuel oil compounds and effects on animals

The barge Florida spilled No. 2 fuel oil into Buzzards Bay, Massachusetts on 29 September 1969. Sediments from five of the original stations were sampled in August 1989 and analysed for fuel oil hydrocarbons. Two subtidal and one intertidal marsh station showed no evidence of fuel oil. One subtidal mud core had traces of biodegraded fuel oil at 10–15 cm. One marsh core contained 10⁻⁶ g g⁻¹ dry wt of weathered and biodegraded fuel oil aromatic hydrocarbons and cycloalkanes at 5–10 cm with lesser concentrations at 0–5 and 10–15 cm. Although present in trace concentrations, these hydrocarbons appear to be slightly inducing cytochrome P4501A in marsh fish (Fundulus heteroclitus).     

SAR observation and model tracking of an oil spill event in coastal waters

Oil spills are a major contributor to marine pollution. The objective of this work is to simulate the oil spill trajectory of oil released from a pipeline leaking in the Gulf of Mexico with the GNOME (General NOAA Operational Modeling Environment) model. The model was developed by NOAA (National Oceanic and Atmospheric Administration) to investigate the effects of different pollutants and environmental conditions on trajectory results. Also, a Texture-Classifying Neural Network Algorithm (TCNNA) was used to delineate ocean oil slicks from synthetic aperture radar (SAR) observations. During the simulation, ocean currents from NCOM (Navy Coastal Ocean Model) outputs and surface wind data measured by an NDBC (National Data Buoy Center) buoy are used to drive the GNOME model. The results show good agreement between the simulated trajectory of the oil spill and synchronous observations from the European ENVISAT ASAR (Advanced Synthetic Aperture Radar) and the Japanese ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array L-band Synthetic Aperture Radar) images. Based on experience with past marine oil spills, about 63.0% of the oil will float and 18.5% of the oil will evaporate and disperse. In addition, the effects from uncertainty of ocean currents and the diffusion coefficient on the trajectory results are also studied.     

Sediment resuspension events within the (microtidal) coastal waters of Thermaikos Gulf, northern Greece

High-frequency flow, pressure and suspended sediment concentration (SSC) measurements are presented from the Paralia-Katerinis coastal area, in Thermaikos Gulf. The data were collected along a cross-shore transect, between the 6 and 12 m water depth contours. The relative importance of wave- and tidally-induced resuspension is examined. Resuspension events are shown to be dominated by wind-generated waves, especially under storm conditions. Some evidence is provided for tidal resuspension, but the overall impact of this process is minimal, compared to wave resuspension. Such resuspension, under storm conditions, increased the SSC levels in the waters of the nearshore zone to 35 mg/l; this is a >15-fold increase over the ambient levels (1–2 mg/l) of turbidity.     

Monitoring biomarkers in fish (Lepidorhombus boscii and Callionymus lyra) from the northern Iberian shelf after the Prestige oil spill

Hepatic biomarker responses were measured in two demersal fish species (Lepidorhombus boscii and Callionymus lyra) from the northern Iberian shelf associated with the massive Prestige oil spill (POS), five months after the accident. The biomarkers selected were 7-ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST), glutathione reductase (GR), catalase (CAT), and DNA integrity. Interspecies differences and spatial variations in biomarker responses were observed along the shelf. GST, GR and CAT activities were significantly elevated in L. boscii in the most oil impacted area (Finisterre) and positively correlated (p<0.05) with POS tar aggregate densities. The lack of previous data from the area together with the existence of chronic background pollution of the shelf implies that the observed biomarker responses cannot be solely attributed to the petroleum hydrocarbon components of the spilled oil. This first biological effect assessment showed that L. boscii is a potentially suitable target species to be used in future biomonitoring programmes along the northern Iberian shelf.     

The state of a river in pechora basin after an oil spill: Assessment of changes in zooplankton community

The long-term dynamics of zooplankton in a northern river has been studied in the context of its pollution after an oil pipeline break. Oil has been shown to have both negative and stimulating effect on planktonic communities and populations, and the role of the drainage area in river system self-purification is studied. Artificial settling water bodies, which had been formed by regulation of polluted flows in the river, have been found to have additional significance as biological regenerators of aquatic ecosystems.     

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.     

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.     

Distribution and photoreactivity of chromophoric dissolved organic matter in northern Gulf of Mexico shelf waters

The distribution and photoreactivity of chromophoric dissolved organic matter (CDOM) in the northern Gulf of Mexico along the Louisiana coastal shelf were examined during three cruises in summer 2007, fall 2007, and summer 2008. The influence of the Mississippi River plume was clearly evident as CDOM levels (defined as a₃₀₅) and dissolved organic carbon (DOC) concentrations were well-correlated with salinity during all cruises. Elevated CDOM and CDOM:DOC ratios of surface samples collected offshore of Atchafalaya Bay and the Breton-Chandeleur Sound complex indicated emanations of organic-rich waters from coastal wetlands are also an important source to nearshore shelf waters. Generally, CDOM and DOC levels were highest in surface waters and decreased with depth, but during summer 2007 and summer 2008, CDOM levels in near-bottom samples were occasionally higher than at mid-depths without concomitant increases in DOC. CDOM photobleaching was measured during 24 irradiations using a SunTest XLS+ solar simulator with photobleaching rate coefficients (k₃₀₅) ranging from 0.011 to 0.32 h⁻¹. For fall 2007 and summer 2008, higher k₃₀₅ values were generally observed in samples with higher initial CDOM levels. However, samples collected during summer 2007 did not exhibit a similar pattern nor were there differences in photobleaching rates between surface and bottom samples. Spectral slope coefficients (S_275-295 or S_350-400) and DOC levels were largely unchanged after 24 h irradiations. Modeled CDOM photobleaching for northern Gulf of Mexico mid-shelf waters predicts that during the summer when solar irradiance is high and the water column becomes stratified, nearly 90% of the CDOM in the upper 1 m may be lost to photobleaching, with losses up to 20% possible even at 10 m depth.     

The influence of cyanobacteria on oil polluted intertidal soils at the Saudi Arabian Gulf shores

In 1991 the second Gulf War lead to the largest oil spill in human history. Over 770 km of coastline from southern Kuwait to Abu Ali Island (Saudi Arabia) were smothered with oil and tar, erasing most of the local plant and animal communities. In the following year cyanobacteria colonized most of the oil polluted shores. In the study area at the Saudi Arabian Gulf coast north of Jubail three different processes were observed that followed the extensive formation of cyanobacterial mats. The first one is desiccation, cracking, and peeling of the cyanobacterial mats, thereby removing the uppermost part of the oiled sediment. The second is the resettlement of burrowing macrofauna like crabs and benthic animals such as gastropods, which outcompete the cyanobacteria again. The third process is further extensive growth of cyanobacteria building thick laminated mats. These layers, completely seal the surface and hence produce an anaerobic milieu which inhibits oil degradation. As long as such cyanobacteria exist, they will prevent microbial oil degradation as well as any resettlement by macrofauna.     

Long term monitoring of meiofauna densities after the Amoco Cadiz oil spill

Long term temporal variations in nematode and copepod densities were monitored in the upper and lower part of the Bay of Morlaix (West Channel), which was heavily contaminated by the 1978 Amoco Cadiz oil spill. Deseasonalization of abundance data allowed estimates to be made of the different components, namely the annual and seasonal trends and the residue. Reduced nematode abundance was long lasting in both types of sediment investigated: it appeared to be a gradual decrease in sublittoral sand but there was a dramatic reduction in estuarine mud 2 years after disturbance. Copepod variability, however, was related to seasonal factors.     

A Bayesian network for analyzing biological acute and long-term impacts of an oil spill in the Gulf of Finland

Knowledge of oil-induced impacts from the literature and experts were used to develop a Bayesian network to evaluate the biological consequences of an oil accident in the low-saline Gulf of Finland (GOF). Analysis was carried out for selected groups of organisms. Subnetworks were divided into subgroups according to a predicted response to oil exposure. Two scenario analyses are presented: the most probable and the worst-case accident.The impact of the most probable accident in the GOF is rather small. In most of the groups studied oil-induced long-term effects are evaluated to be minor at least from the perspective of the whole GOF. After the worst-case accident negative effects are more likely. The model predicts that the most vulnerable groups are auks and ducks. Amphipods, gulls and to a lesser extend littoral fishes and seals may show delayed recovery after an accident. Also annual plant species may be susceptible to oil-induced disturbances.     

The bacterial community composition of an active oil field in the northwestern Gulf of Mexico

The bacterial composition of the water column around two oil production platforms and a control site was examined. Samples were collected during three seasons of a 12-month sampling period three water depths were sampled at all stations occupied.No major differences were discovered in taxonomic or physiological makeup of bacterial populations of the oil field and control site. The genus Pseudomonas predominated at the oil field stations and the control. Bacterial numbers were lower for oil field stations than the control and generally decreased with depth. Microbial biomass estimates were consistently higher at the control site. Oil degrading and sulphur oxidizing bacteria were more numerous within the oil field, and their numbers decreased with distance from the platforms. Buccaneer crude oil did not adversely affect growth or attachment ability of oil field isolates.