Impact of crude oil on sulphate reduction and methane production in sediments impacted by the Amoco Cadiz oil spill

The activities of methane-producing and sulphate-reducing bacteria in intertidal sediments along the Brittany coast of France were examined in order to determine the effect of the Amoco Cadiz oil spill on sediment microbial processes. Porewater chemistry, methane production, sulphate rate and [2?¹⁴C]-acetate metabolism did not vary significantly between beach, estuary, and marsh sites, oiled or unoiled, after the Amoco Cadiz spill. Oiled sediments contained highly weathered oil of Amoco Cadiz origin, but unoiled comparison sites also contained hydrocarbons from anthropogenic sources. The additions of weathered Amoco Cadiz mousse, fresh and slightly weathered light Arabian crude oil, benzene or toluene to sediments from the oiled and unoiled marsh site did not significantly affect rates of sulphate reduction or methane production. The oxidation of [2?^14C]-acetate to ¹⁴CO₂, however, was significantly decreased when mousse, crude oil, benzene or toluene was added to sediments from the unoiled site. Inhibition seemed to be proportional to the extent of weathering. Sediments recently exposed to Amoco Cadiz crude oil were less affected by a second oiling, suggesting that the indigenous populations may have been replaced by organisms more resistant to oil toxicity. These results suggested that the Amoco Cadiz oil spill did not have major long-term effects on sulphate reduction or methane production.     

Exposure to hydrocarbons 10 years after the Exxon Valdez oil spill: evidence from cytochrome P4501A expression and biliary FACs in nearshore demersal fishes

Three biomarkers of hydrocarbon exposure, CYP1A in liver vascular endothelium, liver ethoxyresorufin O-deethylase (EROD), and biliary fluorescent aromatic compounds (FACs), were examined in the nearshore fishes, masked greenling (Hexagrammos octogrammus) and crescent gunnel (Pholis laeta), collected in Prince William Sound, Alaska, 7-10 years after the Exxon Valdez oil spill (EVOS). All biomarkers were elevated in fish collected from sites originally oiled, in comparison to fish from unoiled sites. In 1998, endothelial CYP1A in masked greenling from sites that were heavily oiled in 1989 was significantly higher than in fish collected outside the spill trajectory. In 1999, fishes collected from sites adjacent to intertidal mussel beds containing lingering Exxon Valdez oil had elevated endothelial CYP1A and EROD, and high concentrations of biliary FACs. Fishes from sites near unoiled mussel beds, but within the original spill trajectory, also showed evidence of hydrocarbon exposure, although there were no correlations between sediment petroleum hydrocarbon and any of the biomarkers. Our data show that 10 years after the spill, nearshore fishes within the original spill zone were still exposed to residual EVOS hydrocarbons.     

The long-term effects of crude oil on microbial processes in subarctic marine sediments

Subarctic marine sediments were exposed to fresh and ‘weathered’ crude oil from Cook Inlet, Alaska. The crude oil was thoroughly mixed with the sediment at various concentrations and some of the oil-sediment mixtures were placed on top of unamended sediments. Both sediments with added oil and those overlain by oiled sediments were investigated. These sediments were placed either in trays or aquaria. The trays were incubated in situ near the site from which the sediments were originally collected. The aquaria were maintained at simulated in situ conditions by maintaining a continuous flow of fresh seawater through them. The sediments were exposed to crude oil for periods up to 1.5 years. Sediments exposed to 50‰ fresh crude oil showed significant decreases in nitrogen fixation and denitrification rates and redox potentials. Also observed were increases in CO₂ production rates and methane concentrations. These same changes were observed in sediments exposed to 1‰. When ‘weathered’ crude oil was added to the sediments, the same changes were observed except there was no reduction in nitrogen fixation activity. In most cases, the observed effects were less marked when the sediments were amended with ‘weathered’ crude oil than with the same concentration of fresh crude oil. Untreated sediments that were overlain with treated sediments showed the same changes as those sediments that were thoroughly mixed with crude oil. The presence of fresh crude oil at 50‰ essentially eliminated burrowing activity of the benthic infauna. Under these conditions, there was an accumulation of detritus particles on the oiled sediments that was not present in the untreated controls.     

Influence of Naineris laevigata (Polychaeta: Orbiniidae) on vertical grain size distribution,and dinoflagellate resting stages in the sediment

Short-term experiments were performed with the polychaete Naineris laevigata Grube, a conveyor-belt deposit feeder, to evaluate: the daily sediment reworking rate, the influence of the activity of this burrowing worm on the vertical redistribution of the sediment and dinoflagellate cysts. We also tested the germination success of cysts after their passage through the gut of the polychaete. Vertical particle distribution was studied in small aquaria with and without worms and with an initially layered sediment. After 30 days, sediment cores were collected in controls and treatments at 3 different depths (upper, intermediate and deep) and the diameter of 100 particles from each depth was measured to obtain the size-frequency distribution. The burrowing activity of 3 worms may completely mix a pre-existent layering within 30 days. The translocation of a mud layer from 4 cm depth towards the surface was observed. The mud layer deposited on the surface by the end of the experiment was at least 1 cm thick.Daily average production of faecal pellets was 0.443±0.032 g per worm. From the first day of the experiment, the particle size distribution of the faecal pellets released at the surface revealed the presence of sediment and cysts originating from underlying layers. Tests showed that the germination percentage of the cysts significantly diminished after passage through the guts of the worms.Our results indicate that N. laevigata is an effective vertical mixer of sediment and plays a role in the vertical transport and germination success of resting stages.     

The burrowing behavior of sand lance, Ammodytes hexapterus: Effects of oil-contaminated sediment

Whilst foraging in the water column for zooplankton, sand lance, Ammodytes hexapterus, are under heavy predation from marine birds and fish. To avoid predation, sand lance bury in the sand when not foraging and during overwintering. We did two experiments to determine whether oil contamination of the sand would reduce the amount of time that sand lance spent buried. In the first experiment (June, 1980) sand lance significantly decreased by 20% the time spent buried in oiled sand (306 ppm). In the second experiment (June, 1981) sand lance did not decrease time spent buried in oiled sand at 28 and 256 ppm but did at 3384 ppm. The higher condition index of the 1981 fish suggested that nutritional state may have influenced how sand lance used the sediment as a refuge and how they responded to contamination of that refuge.     

Fate and effects of a heavy fuel oil spill on a Georgia salt marsh

Addition of a heavy oil to a Spartina salt marsh in the autumn resulted in high concentrations of polycyclic aromatic hydrocarbons in sediment and benthic animals. The highest concentrations of phenanthrene, chrysene and fluoranthene in the sediment were 112, 105 and 75 ng/g sediment, respectively. These concentrations rapidly decreased during the 20 week period following the spill. The times for these hydrocarbons to decrease to 50% of their highest values, i.e. half-life, were approximately 100, 70 and 30 days in sediment, mussels and oysters, respectively. Benthic macrofauna species showed three responses to oil addition which included no change, an increase, or a decrease in the population. No changes were noted in populations of fiddler crabs (Uca pugnax), oysters (Crassostrea virginica), and mussels (Modiolus demissus). Mud snails (Nassarius obsoleta) increased in density after the spill due to immigration of adult snails from untreated areas to scavenge on animals killed by the oil. Many of the adult periwinkles (Littorina irrorata) were killed by the oil. In the spring, juvenile periwinkles recolonised to oiled areas as a result of larvae settling.     

Initial impact of the Treasure oil spill on seabirds off western South Africa

On 23 June 2000, the bulk ore carrier MV Treasure sank off western South Africa between Dassen and Robben islands, which individually currently support the largest and 3^rd largest colonies of African penguins Spheniscus demersus. Subsequently, more than 19 000 penguins were oiled, almost twice the previous highest number of seabirds oiled during a single event in southern Africa (10 000 penguins after the sinking of the Apollo Sea in June 1994). About 19 000 oiled penguins were collected for cleaning and care and about 150 oiled adults died in the wild. Some 19 500 unoiled penguins were caught at Dassen and Robben islands and relocated to Port Elizabeth, 800 km to the east, to remove them from waters affected by the oil. Of all penguins caught, which amounted to 20% of the total species population, less than 2 000 died within the first month, considerably less than in the Apollo Sea spill. This can be attributed to improved transport of penguins and the rapid arrival at rescue centres of experts able to administer emergency care. However, resources were severely extended and mortality would probably have been considerably higher had large numbers of birds not been removed from the area affected by the oil. Many relocated birds returned to their home islands within a month of being released, but considerable disruption of pair bonds is expected to result from mortality, different periods in captivity and disruption of moult cycles. This is likely to result in decreased breeding success. Recruitment to colonies will also be reduced by substantial loss of chicks and eggs. Although more than 3 000 orphaned chicks were collected for captive rearing, an estimated 4 000 died at the islands before they could be rescued. Up to 20% of bank cormorants Phalacrocorax neglectus at Robben Island, the 3^rd largest colony of the species in South Africa, died. There was low success in catching oiled cormorants and in saving those that were caught. Of 53 grown birds of four species of cormorant that were oiled and caught, only 17 survived. Captive rearing of bank cormorant chicks, which it was feared may have been orphaned, proved more successful. Spilt oil had minor impact on gulls, terns and shorebirds in the region.     

Restoration of oiled mussel beds in Prince William Sound, Alaska

Natural loss of hydrocarbons was often low from mussel (Mytilus trossulus) beds (which were typically not cleaned after the Exxon Valdez oil spill), thus this habitat remained a long-term source of oil. Consequently, experimental restoration of nine contaminated beds was attempted in 1994; mussels were removed, contaminated surface sediment was replaced (33 metric tons), and original mussels were returned. Hydrocarbon concentrations and mussel populations were monitored for 5 years thereafter. Post-restoration mussel population fluctuations were indistinguishable from regional changes. Increased short-term oil loss was apparent, but long-term (5 year) improvement was equivocal and difficult to distinguish from natural losses. By 1999, oil concentrations in mussels were typically at baseline levels in restored and oiled reference beds; concentrations in replaced sediment were elevated in one third of restored beds, indicating recontamination from underlying or surrounding sediment. Our results suggest mussel relocation is feasible but suggest oil might more effectively be removed from sediment mechanically or chemically than manually.     

Spilled Oil and infaunal activity—modification of burrowing behavior and redistribution of oil

A series of experiments in Willapa Bay, Washington, indicates the degree to which the presence of spilled oil modifies the burrowing behavior of infauna and the extent to which the animals redistribute oil into interridal sediment. Small amounts of North Slope crude oil introduced at low tide directly into burrow openings (mostly made by the crustacean Callianassa) resulted in a limited and temporary reduction in the number of burrow openings. In contrast, a layerof oil-saturated sand 1 cm thick buried about 5 cm below the sediment surface sharply reduced the number of burrow openings. After a year, the few new burrows penetrated only the margins of the experimental plot, and bioturbation below the buried oil saturated sand layer declined dramatically.The experiments suggest that small amounts of oil temporarily stranded by tides in themselves have no long-range effect on burrowing behavior. The fauna, however, are capable of introducing measurable amounts of oil into the subsurface, where it is retained long after the rest of the stranded oil has washed away. A buried layer of oil-saturated sand greatly reduces infaunal activity; the oil presents an effective barrier that can persist for years.The oil incorporated into the sediment from burrow openings showed evidence of degradation after 7 months. In contrast, the layer of buried oil remained essentially undegraded after a period of two years, even though oil in lower concentrations above the layer was degraded after a period of one year. This variation in degree of dgradation of the buried oil, as well as the heterogeneity of oil distribution wherever the oil has been incorporated from the surface, emphasises the importance of careful sampling in any attempt to locate or monitor the presence of spilled oil in the substrate.     

Toxicological effects induced by the nanomaterials fullerene and nanosilver in the polychaeta Laeonereis acuta (Nereididae) and in the bacteria communities living at their surface

Fullerene (nC₆₀) and nanosilver (nAg) are nanomaterials with bactericide properties. The increments in their use raise questions about their potential environmental impacts, including estuarine ones. The polychaete Laeonereis acuta (Nereididae) secretes mucus that is colonized by bacteria communities. We analyzed the antioxidant and oxidative damage responses of anterior, middle and posterior region of L. acuta and bacteria communities after nC₆₀ or nAg exposure during 24 h. Molecular analysis showed a prevalence of Vibrio genera in the communities. Bacteria biomass was lowered in worms exposed to 1.0 mg/L of nAg. nC₆₀ reduced total antioxidant capacity of bacteria from worms exposed to 0.1 mg/L. Worms anterior region presented lower antioxidant capacity after exposure to 1.0 mg nC₆₀/L, and the same was observed in the posterior region of worms exposed to 1.0 mg nAg/L. Lipid peroxidation was reduced in the anterior region of worms exposed to nC₆₀ and the opposite was observed in the posterior region.     

Respiratory changes and stability of haemocyanin—O2 binding capacity in the crab cancer irroratus exposed to Kuwait crude oil in sea water

To determine one possible mechanism of hydrocarbon toxicity, studies were carried out to establish: (a) the availability of hydrocarbons from sea water to the crab haemolymph, (b) the effects on respiration and (c) the possible effects on haemocyanin—O₂ binding characteristics in oiled crabs.Crabs incubated in ¹⁴C-naphthalene labelled oiled sea water (Kuwait crude) readily accumulated the isotope into the haemolymph, in concentrations exceeding those in the surrounding sea water medium with one-hour bioconcentration factors from 2·53 to 23·51. Respiration, as measured by uptake of O₂ from the respirometer sea water, was 12·5% lower in crabs held in 11·0 ppm Kuwait crude/sea water than in the same animals when held in unoiled sea water. Respiration levels returned to preoiling levels when the oiled sea water was replaced with fresh non-oiled sea water.Despite the observed effects of oiled sea water on respiration, the haemocyanin—O₂ binding potential, as well as the structural integrity of haemocyanin (as determined by its UV absorption spectrum, sub-unit dissociation and serum-free Cu⁺⁺ levels), remained unaltered. The results suggest that disruption of blood-oxygen transport via disruption of haemocyanin—O₂ binding as one possible mechanism of hydrocarbon toxicity is unlikely and that other alternatives must be considered.     

Effects of macroalgal mats and hypoxia on burrowing depth of the New Zealand cockle (Austrovenus stutchburyi)

Macroalgal mats commonly occur in estuaries and sheltered embayments where they are thought to affect the oxygen conditions in the sediment, influence the geochemical process and influence the burrowing activity of bivalves. Laboratory experiments evaluated the effects of sediment hypoxia and algal mats on the burrowing ability and survival of the New Zealand cockle Austrovenus stutchburyi at 15 °C. Both dissolved oxygen concentration and time affected the burial depth of the cockles over the 12 days of the experiment. In hypoxic conditions (<2 mg L^?1), cockles migrated to the sediment surface after 3.5 days and mortality occurred after 11 days. Bivalves exposed to oxygen concentrations of 2–3 mg L^?1 buried closer to the sediment surface than those in the other treatments. Using a simulated tidal regime, in a mesocosm, burrowing behaviour of the cockle and pore-water oxygen conditions in the sediment were measured on exposure to experimental mats of Gracilaria chilensis and Ulva spp. for over 6 days. Algal mats on the surface of the sediment significantly lowered the dissolved oxygen concentration of the sediment pore-water and this effect was greater for the Ulva spp. treatment than the G. chilensis treatment. Cockles were buried more deeply in the control treatment without algae than in either of the two algal treatments. It is concluded that reduced oxygen conditions (<3.5 mg L^?1) develop under macroalgal mats and that this reduces the burial depth of cockles. The potential harmful effects of the mats can depend on the species forming the mat and these effects are likely to be greater in the field than they are in controlled laboratory conditions.     

Exposure of pink salmon embryos to dissolved polynuclear aromatic hydrocarbons delays development,prolonging vulnerability to mechanical damage

Exposure to dissolved polynuclear aromatic hydrocarbons (PAHs) from crude oil delays pink salmon (Oncorhynchus gorbuscha) embryo development, thus prolonging their susceptibility to mechanical damage (shock). Exposure also caused mortality, edema, and anemia consistent with previous studies. Hatching and yolk consumption were delayed, indicating the rate of embryonic development was slowed by PAH exposure. The net result was that exposed embryos were more susceptible to shock than normal, unexposed embryos. Susceptibility to shock was protracted by 4–6 d for more than a month in embryos exposed to exponentially declining, dissolved PAH concentrations in water passed through oiled rock; the initial total PAH concentration was 22.4 μg L⁻¹ and the geometric mean concentration was 4.5 μg L⁻¹ over the first 20 d. Protracted susceptibility to shock caused by exposure to PAHs dissolved from oil could potentially increase the reported incidence of mortality in oiled stream systems, such as those in Prince William Sound after the Exxon Valdez oil spill, if observers fail to discriminate between direct mortality and shock-induced mortality.     

The importance of bioturbation to continental slope sediment structure and benthic processes off Cape Hatteras, North Carolina

Even though the continental slope off Cape Hatteras has sediment accumulation rates on the order of 1 cm/year, large areas of soft sediment are intensively reworked by infaunal organisms. Primary sedimentary structures have been completely replaced with biogenic structures. Surface sedimentary structures are dominated by the bioturbational activities of a deep burrowing infauna (to at least 30 cm). The layer actively mixed by the benthos, as evidenced by sediment profile and X-ray images, is estimated to range from 5 to 20 cm, with the residence time for particles within the surface mixed layer ranging from about 4.5 to 18 years. The biological mixing parameter (G) ranges from 0.4 to 5.5, which indicates moderate to strong biological mixing relative to accumulation and strata formation. Bioturbation contributes to the dynamic forces affecting the surface sediments by decreasing compaction of sediment layers and dilating sediment fabrics by sediment mixing, and introducing large water-filled burrows and voids to subsurface sediments. The sediment profile images captured numerous subsurface feeding voids, and worms in the process of making deep burrows, many of which extended below the 5 to 10 cm average depth of the apparent color redoxpotential discontinuity layer. High rates of accumulation of organic-rich sediment lead to high standing stocks of benthos and intensive feeding/burrowing activity that result in organic rich stratagraphic sequences that are thoroughly mixed. Cape Hatteras is a apparent focusing point for the transport of shallow water sediments to the deep sea. Sediments across other areas of the continental slope just 100's of kilometers south of Cape Hatteras are not as thoroughly mixed or biologically active.     

Mussels document loss of bioavailable polycyclic aromatic hydrocarbons and the return to baseline conditions for oiled shorelines in Prince William Sound, Alaska

Polycyclic aromatic hydrocarbons (PAH) were measured in mussels (Mytilus trossulus) collected between 1990 and 2002 from 11 sites on the shores of Prince William Sound (PWS), Alaska, that were heavily oiled by the 1989 Exxon Valdez oil spill (EVOS). This study, utilizing the methods of the NOAA Status and Trends Mussel Watch Program, found that concentrations of PAH released from spill remnants have decreased dramatically with time and by 2002 were at or near the range of total PAH (TPAH) of 3-355 ng/g dry weight obtained for mussels from unoiled reference sites in PWS. Time-series TPAH data indicate a mean TPAH half-life in mussel tissues of 2.4 years with a range from 1.4 to 5.3, yielding an annual mean loss of bioaccumulated TPAH of 25%. The petroleum-derived TPAH fraction in mussel tissues has decreased with time, reflecting the decreasing release of EVOS residues in shoreline sediments. These results show that PAH from EVOS residues that remain buried in shoreline sediments after the early 1990s are in a form and at locations that have a low accessibility to mussels living in the intertidal zone.     

Sedimentary organic matter distributions,burrowing activity,and biogeochemical cycling: Natural patterns and experimental artifacts

The coupling between biogenic reworking activity and reactive organic matter patterns within deposits is poorly understood and often ignored. In this study, we examined how common experimental treatments of sediment affect the burrowing behavior of the polychaete Nephtys incisa and how these effects may interact with reactive organic matter distributions to alter diagenetic transport – reaction balances. Sediment and animals were recovered from a subtidal site in central Long Island Sound, USA. The upper 15 cm of the sediment was sectioned into sub-intervals, and each interval separately sieved and homogenized. Three initial distributions of sediment and organic substrate reactivity were setup in a series of microcosms: (1) a reconstituted natural pattern with surface-derived sediment overlying sediment obtained from progressively deeper material to a depth of 15 cm (Natural); (2) a 15 cm thick sediment layer composed only of surface-derived sediment (Rich); and (3) a 15 cm thick layer composed of uniformally mixed sediment from the original 15 cm sediment profile (Averaged). The two last treatments are comparable to that used in microcosms in many previous studies of bioturbation and interspecific functional interaction experiments. Sediment grain size distributions were 97.5% silt-clay and showed no depth dependent patterns. Sediment porosity gradients were slightly altered by the treatments. Nepthys were reintroduced and aquariums were X-rayed regularly over 5 months to visualize and quantify spatial and temporal dynamics of burrows. The burrowing behaviour of adult populations having similar total biovolume, biomass, abundance, and individual sizes differed substantially as a function of treatment. Burrows in sediment with natural property gradients were much shallower and less dense than those in microcosms with altered gradients. The burrow volume/biovolume ratio was also lower in the substrate with natural organic reactivity gradients. Variation in food resources or in sediment mechanical properties associated with treatments, the latter in part coupled to remineralization processes such as exopolymer production, may explain the burrowing responses. In addition to demonstrating how species may respond to physical sedimentation events (substrate homogenization) and patterns of reactive organic matter redistribution, these experiments suggest that infaunal species interactions in microcosms, including the absolute and relative fluxes of remineralized solutes, may be subject to artifacts depending on exactly how sediments are introduced experimentally. Nonlocal transport and cylinder microenvironment transport – reaction models readily demonstrate how the multiple interactions between burrowing patterns and remineralization rate distributions can alter relative flux balances, decomposition pathways, and time to steady state.     

The relative importance of water and diet for uptake and subcellular distribution of cadmium in the deposit-feeding polychaete, Capitella sp. I

The impact of dietary and water exposure on the accumulation and distribution of cadmium (Cd) in subcellular components of the polychaete Capitella sp. I was investigated. Worms were exposed to either dissolved Cd alone ('Water-Only' treatments; WO) or diet-bound Cd alone ('Algae-bound Only' treatments; AO). Thus, WO worms were starved and AO worms were fed. Differential centrifugation was used to fractionate worm homogenates into debris- (DE), mitochondrial- (MI), microsomal- (MC) and cytosolic- (CY) fractions, and the concentration of Cd in these fractions was quantified by radiometric analysis using the specific activity of the (109)Cd radioisotope. Neither exposure route nor Cd exposure affected the total protein content in the worms. However, fed, but not starved worms relocated proteins from the mitochondria to the cytosol in response to Cd exposure. In systems without Cd addition, starvation likewise influenced the distribution of protein between mitochondria and cytosol. Cutaneous uptake and accumulation of Cd from the water was related to surface area while dietary uptake was influenced by the amount of sediment passing through the gut. Irrespective of exposure route, Cd was accumulated primarily in the debris fraction although comparisons between the treatments indicated that relatively less Cd was located in DE and more in MI, MC and CY fractions in worms in AO compared to worms in WO. Cd per unit protein in DE and MI fractions was twice as high as in MC and CY fractions in WO, whereas MC contained the highest Cd content followed by MI, DE and CY fractions in AO worms. Our results stress the importance of exposure route for the internal distribution and toxicity of Cd to deposit feeders such as Capitella sp. I.     

Incorporation,distribution and fate of saturated petroleum hydrocarbons in sediments from a controlled marine ecosystem

A simulation of a chronic input of petroleum into an estuarine environment was investigated using the facilities at the Marine Ecosystems Research Laboratory at the University of Rhode Island. An oil-water dispersion of No. 2 fuel oil was added to the system (twice weekly for 24 weeks) and the saturated hydrocarbons from this oil were measured in suspended material and sediments. After the initial chronic oil addition, trace amounts of hydrocarbons were detected in the sediments within two weeks, but substantial accumulation was not detected for approximately 135 days. The oil appeared to enter the sediment via the suspended material, with most of the saturated hydrocarbons associated with smaller size sediment particles (< 45 μm to > 0·3 μm). With time, the fuel oil saturated hydrocarbons in the sediments were mixed to a depth of 3 to 4 cm. Although only 12% of the total saturated hydrocarbons added to the system were found in the sediments, these hydrocarbons appear to be relatively stable and were still detectable in these sediments for at least six months after the last oil addition.     

Response of benthic communities in merl experimental ecosystems to low level, chronic additions of No. 2 fuel oil

The macrofauna and meiofauna of three oiled and three control experimental ecosystems at the Marine Ecosystems Research Laboratory (MERL) were followed for 25 weeks of semi-continuous additions of an oil-water dispersion of No. 2 fuel oil. Water column hydrocarbon levels were maintained at about 190 ppb, and after 20 weeks 109 sm/g dry weight fuel oil hydrocarbons were recorded in the top 2 cm of sediment.This simulated chronic oil pollution resulted in a highly significant decline in the number of macrofaunal and meiofaunal individuals in the experimental tanks compared with the controls. The effect was apparent on the numbers of individual macrofaunal species and on all metazoan meiofaunal groups.     

Effects of high pressure,hot water shore cleaning after oil spills on shore ecosystems in the Northern Baltic proper

The use of high pressure, hot water hosing techniques in oil spill clean-up operations on rocky and stony-gravelly shores drastically reduces the shore vegetation and macrofauna. The negative effects are more substantial than on oiled shores cleaned by raking and scraping. After one year the hot water cleaned shores were not restored completely.On rocky shores the high pressure, hot water technique is very efficient in terms of freeing the rocks from oil. However, due to its detrimental effects on shore organisms this type of oil spill clean-up operation can only be recommended for bird or wildlife protection areas. The cleanup method is inefficient on stony-gravelly shores due to penetration of oil into the ground and sediment and direct killing of shore organisms. The method should be avoided on these types of shores.