Mexican oil spill: A toxicity study of oil accommodated in seawater on marine invertebrates

The Mexican Ixtoc oil well blew out on 3 June, 1979. Since then more than 3.5 × 10⁵ tonnes of crude oil have entered the Gulf of Mexico. This is probably the largest oil spill in the world's history. Two months later (7 August, 1979), the spilled oil began moving to the Texas coastal waters and the well is not yet capped. Although laboratory tests showed that the aged oil was not acutely toxic to some marine invertebrates, further work needs to be conducted to determine its possible chronic effects on sensitive ecosystems such as the Laguna Madre.     

Effects of nitrogen and sulphide on macroinfaunal community: a microcosm study

A microcosm experiment was conducted to test the short-term effects of nitrogen (as TKN, total Kjeldahl nitrogen) and sulphide (as AVS, acid volatile sulphide) on macrobenthic infauna over a period of 8 weeks. The experiment consisted of four treatments using sediment cores (D: 8 cm, H: 20 cm) with addition of: I, nitrogen (N) to an in situ mean level of 0.48 mg Ng(-1) dw; II, sulphidic solution (S) to an in situ mean level of 318.8 microM S g(-1) dw; III, nitrogen and sulphidic solution (NS) to in situ mean levels of 0.45 mg Ng(-1) dw and 329.0 microM S g(-1) dw, respectively, and IV, control with no addition of N and S. Sediment cores were retrieved for analysis of infaunal composition after weeks 2, 4 and 8. A total of 646 specimens of macrobenthic infauna belonging to 27 species were recorded from the cores, in which polychaetes were the most abundant with respect to species and individual numbers. Mean species number and diversity H' of the control and N treatment was statistically higher than S and NS treatments, mean individual number of the S treatment was larger than the NS treatment, and mean evenness J of the S treatment was lower than the N and NS treatments as well as the control. Individual numbers also showed a significant increase from weeks 2 to 8, whereas evenness J decreased in weeks 4 and 8. Multivariate analyses of the faunal data suggested that benthic composition of the N treatment and control did not differ during the experimental period, but changes in benthic structure in S and NS treatments were evident. The present findings demonstrated the dose-response relationship of benthic species changes under controlled addition of N and S. The response to N and S additions in the sediment microcosms was in agreement with the general effects of organic enrichment on macrobenthic communities along a spatial gradient of organic pollution as described by Pearson and Rosenberg [Pearson, T.H., Rosenberg, R., 1978. Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanography and Marine Biology Annual Review 16, 229-311]. However, in the present experiment, community changes in the treatments were observable in a short, temporal scale.     

Impacts of the Jessica oil spill on sea lion (Zalophus wollebaeki) populations

Following the Jessica oil spill, a total of 79 oiled Galápagos sea lions (Zalophus wollebaeki) were recorded around the islands of San Cristóbal, Santa Fé, Isabela and Floreana. Almost half of these animals required washing and other treatment. One sea lion death and a high incidence of conjunctivitis and burns were detected during the period of the oil spill. Sea lion populations exhibited a tendency for decline in the first months following the spill at all three colonies monitored close to the grounding site on San Cristóbal. By comparison, declines of similar magnitude occurred at only one of six sea lion colonies monitored on islands more distant from the spill. However, no significant decreases in population numbers were detected for any colony in the year following the spill. Galápagos sea lion populations were partially recovering from the much more catastrophic impact of the 1997/98 El Ni?o.     

Short-term effects of the prestige oil spill on the peregrine falcon (Falco peregrinus)

We have monitored the distribution, population status, breeding success, turnover rate and diet of a Peregrine Falcon population in Bizkaia (North of Spain) since 1997. On the 13th November 2002, the tanker Prestige sunk off La Coruña (NW Spain) causing an oil spill that affected the whole of the Cantabrian Coast and the Southwest of France. The total number of birds affected by the Prestige oil spill was expected to be between 115,000 and 230,000, some of them raptors. The loss of clutches during the incubation period increased significantly and was correlated with the loss of females. Moreover, the turnover rate of the population increased from 21% to 30%. The polycyclic aromatic hydrocarbon concentrations in the eggs, collected from five nests after they were deserted, ranged from 21.20 ng/g to 461.08 ng/g, values which are high enough to cause the death of the embryos and poisoning of adult birds. The effects of pollution reached inland since some inland-breeding falcons prey on shorebirds that use rivers during their migratory flights. As the Prestige oil spill has clearly resulted in increased rates of adult mortality and reduced fertility, we suggest that the environmental authorities urgently undertake measures aimed at protecting the Peregrine Falcon in Bizkaia.     

The Gladstone (Australia) oil spill - impacts on intertidal areas: baseline and six months post-spill

In January 2006, 25 tonnes of heavy fuel oil spilled into the Port of Gladstone in Queensland, Australia, from the breached hull of a bulk carrier ship. While approximately 18 tonnes of the oil was recovered, a certain amount of oil was deposited in the intertidal areas of Port Curtis leaving a highly visible, viscous residue. The objectives of this research were to assess the short-term (one month post-spill) and medium-term (six months post-spill) impacts on the intertidal habitat.Sediment polycyclic aromatic hydrocarbons (PAHs) and metal concentrations, mangrove communities and intertidal macroinvertebrates were assessed at oil impacted sites, adjacent sites which were not visibly impacted and reference sites which were located outside the recorded distribution of the oil spill.At one month post-spill, highest PAH concentrations were found at the impacted sites, with concentrations of some PAHs exceeding Australian and New Zealand sediment quality guidelines (SQG) [ANZECC/ARMCANZ, 2000. Sediment Quality Guidelines. Australia and New Zealand Environment and Conservation Council and Agriculture and Resource Management Council of Australia and New Zealand]. However, by six months post-spill PAH concentrations had significantly decreased. PAH concentrations tended to be higher in the back (upper) intertidal zone than at the front of the mangrove stand, and sediment cores indicated that PAH contaminants had remained in the top 4 cm of the sediment. These results indicate that the overall decreased PAH concentrations are likely to be due to evaporation, photoxidation and tidal flushing of the residual oil in these impacted sites.During the initial survey, the impact site contained very few or no crabholes in the high intertidal area, indicating a low crab density in comparison to reference sites. However, at six months post-spill mangrove crab communities appeared to be fully recovered with crabhole densities in impact sites similar to reference sites.While little immediate impact was evident on mangrove parameters, significantly higher seedling mortality and defoliation was apparent at six months post-spill, particularly in the upper intertidal zone. Intertidal macrobenthic communities did not appear to be impacted, either immediately or at six months post-spill. Monitoring of these oil impacted intertidal areas will continue to examine the long-term impacts/recovery from the oil spill.     

Cell and tissue biomarkers in mussel, and histopathology in hake and anchovy from Bay of Biscay after the Prestige oil spill (Monitoring Campaign 2003)

In order to assess the biological effects of the Prestige oil spill (POS), mussels (Mytilus galloprovincialis), European hake (Merluccius merluccius) and European anchovy (Engraulis encrasicolus) were sampled between April and September 2003 in various geographical areas of Bay of Biscay: Galicia, Central Cantabrian and East Cantabrian. In mussels, several cell and tissue biomarkers were measured: peroxisome proliferation as induction of acyl-CoA oxidase (AOX) activity, lysosomal responses as changes in the structure (lysosomal volume density, V(V(L)), surface-to-volume ratio, S/V(L), and numerical density, N(V(L))) and in membrane stability (labilization period, LP), cell type replacement as relative proportion of basophilic cells (volume density of basophilic cells, V(V(BAS))) in digestive gland epithelium, and changes in the morphology of digestive alveoli as mean luminal radius to mean epithelial thickness (MLR/MET). Additionally, flesh condition index (FCI) and gonad index (GI) were measured as supporting parameters. In hake and anchovy, liver histopathology was examined to determine the prevalence of parasites, melanomacrophage centers, non-specific lesions (inflammatory changes, atrophy, necrosis, apoptosis), early non-neoplastic toxicopathic lesions (i.e., hepatocellular nuclear polymorphism), foci of cellular alteration, benign and malignant neoplasms. In mussels, AOX induction was noticeable in April except in Galicia. LP values were low in all the geographical areas studied, indicating disturbed health, especially in Galicia. Alike, lysosomal enlargement was observed in most stations as shown by the extremely low S/V(L) values. V(V(BAS)) and MLR/MET values were markedly high. Overall, employed biomarkers detected exposure to toxic chemicals and disturbed health in mussels from Bay of Biscay, with impact decreasing from April to September. Although hepatocellular nuclear polymorphism and nematode parasitization in fish liver were remarkably prominent in some areas, they cannot be hitherto related to POS, since we lack historical data to determine whether the prevalences found were normal or significantly raised after POS.     

The Sea Empress oil spill (Wales, UK): effects on Common Scoter Melanitta nigra in Carmarthen Bay and status ten years later

Carmarthen Bay, UK, regularly supports internationally important numbers (>16,000) of non-breeding Common Scoters Melanitta nigra. The spill of 72,000 tonnes of crude oil from the Sea Empress in 1996 affected birds both through direct mortality and likely pollution of key food resources. Numbers were greatly reduced following the spill, whilst changes in the distribution of birds within Carmarthen Bay suggested that potentially sub-optimal foraging zones were used. However, ten years after the incident, numbers of Common Scoter were no different to those recorded immediately before the spill. Compared to some other spills, rapid revival is evident. Numbers increased to pre-spill levels within three winters and distributional changes suggested a concurrent return to previously contaminated feeding areas, implying that the ecosystem had regenerated sufficiently to support its top predator. The importance of prolonged, standardised monitoring of bird numbers and distribution as indicators of ecological recovery from environmental damage is emphasised.     

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.     

Interactive effects of hypoxia and polybrominated diphenyl ethers (PBDEs) on microbial community assembly in surface marine sediments

Hypoxia alters the oxidation–reduction balance and the biogeochemical processes in sediments, but little is known about its impacts on the microbial community that is responsible for such processes. In this study, we investigated the effects of hypoxia and the ubiquitously dispersed flame-retardant BDE47 on the bacterial communities in marine surface sediments during a 28-days microcosm experiment. Both hypoxia and BDE47 alone significantly altered the bacterial community and reduced the species and genetic diversity. UniFrac analysis revealed that BDE47 selected certain bacterial species and resulted in major community shifts, whereas hypoxia changed the relative abundances of taxa, suggesting slower but nonetheless significant community shifts. These two stressors targeted mostly different taxa, but they both favored Bacteroidetes and suppressed Gammaproteobacteria. Importantly, the impacts of BDE47 on bacterial communities were different under hypoxic and normoxic conditions, highlighting the need to consider risk assessments for BDE47 in a broader context of interaction with hypoxia.     

Effects of the 2003 European heatwave on the benthic community of a severe transitional ecosystem (Comacchio Saltworks, Italy)

The summer of 2003 was the warmest summer in Europe since the 16th century. Its consequences on the fauna of a transitional ecosystem were studied through biodiversity, functional and ecological indicators, from summer 2002 to winter 2005. The heatwave caused considerable changes in the benthic community structure and relative composition, persisting in 2005. Animal assemblages switched from mollusc- to annelida-dominated. Biodiversity and functional indicators captured changes in community structure and composition, proving to be powerful tools to detect responses related to global warming. Ecological indicators rendered a monotonic response oscillating between bad and poor ecological status across the study period. The resilience of mollusc biocoenosis resulted limited with respect to other taxa, posing concerns about their conservation if, as predicted, the frequency of summers as hot as that of 2003 will progressively increase to become the norm at the end of this century.     

Magma mixing during the 2001 event at Mount Etna (Italy): Effects on the eruptive dynamics

During the 2001 eruptive episode three different magmas were erupted on the southern flank of Mount Etna volcano from distinct vent systems. Major and minor element chemistry of rocks and minerals shows that mixing occurred, and that the mixed magma was erupted during the last eruptive phases.The space–time integrated analysis of the eruption, supported by geophysical data, together with major and trace element bulk chemistry (XRF, ICP-MS) and major and trace mineral chemistry (EPMA, LAM ICP-MS), support the following model: 1) trachybasaltic magma rises through a NNW–SSE trending structure, connected to the main open conduit system; 2) ascent of an amphibole-bearing trachybasaltic magma from a 6 km deep eccentric reservoir through newly open N–S trending fractures; 3) just a few days following the eruption onset the two tectonic systems intersect at the Laghetto area; 4) at the Laghetto vent a mixed magma is erupted.Mixing occurred between the amphibole-bearing trachybasaltic magma and an inferred deep more basic end-member. The most relevant aspect in the eruptive dynamics is that the eruption of the mixed magma at the Laghetto vent was highly explosive due to volatile content in the magma. The gas phase formed, mainly because of the decreased volatile solubility due to rapid fractures opening and increased T, related to mixing, and partially because of the amphibole breakdown.     

Temporal and geographical trends in the genotoxic effects of marine sediments after accidental oil spill on the blood cells of striped beakperch (Oplegnathus fasciatus)

To determine the impact of genetic toxicity caused by the Hebei Spirit oil spill on December 7, 2007, we measured DNA damage in the blood cells of striped beakperch in vitro after exposure to extracts from sediments in the Taean area. The objective of this study was to investigate temporal changes of toxic effects caused by residual PAHs in the sediments up to 18 months after an oil spill. In conclusion, DNA damage had reduced over this 18-month period; that is, the sediments recovered quickly from the oil pollution. In addition, statistically significant correlations between PAHs and DNA damage were observed. Because the comet assay is sensitive to DNA damage induced by genotoxic substances from the polluted sediments, the comet assay can be considered a useful tool as a biomarker in investigating genetic toxicity in environmental monitoring and elucidating the recovery of oil pollution after oil spill as well.     

Nutrient dynamics in Mediterranean temporary streams: A case study in Pardiela catchment (Degebe River, Portugal)

Most of the streams in the Mediterranean region are temporary, following predictable seasonal of flooding and drying, with a transition from lotic conditions to shallow lentic conditions. The goal of our study was to assess the nitrogen and phosphorus dynamics in channel-bed processes of temporary streams between floods. Results show that, during winter, temperatures ranged between 9.5 and 11.2 °C and oxygen concentration ranged from 8.0 to 9.5 mg L⁻¹, whereas, during summer, temperatures varied between 21.2 and 26.8 °C and oxygen between 1.2 and 5.3 mg L⁻¹, with oxygen depletion in the pools during the night. The nitrate concentrations were far more abundant during winter (February), while ammonium concentration increased after stream fragmentation into pools (especially in July when oxygen depletion conditions favoured ammonification). Results on sediment profiles showed that the most active sediment layers for NH₄-N are the top 2–3 cm, corresponding to the sediment depositional sites of the stream. Phosphate concentrations had larger variability, yet concentrations decreased from winter to spring and increased again in summer, when the shallow water pools were formed. Sediment profiles at the sediment depositional sites showed that PO₄-P was more dynamic in the first 6 cm.

In Mediterranean temporary streams, nutrient dynamics vary seasonally, as the system transits from lotic conditions to shallow lentic conditions, evidencing the regeneration of nutrients from organic and inorganic matter during the flow cessation period.     

Effect of magnetic storms (substorms) on HF propagation: A review

The manifestations of the so-called main ionospheric effect during geomagnetic storms (substorms) in the character of decameter-wave propagation are analyzed. On HF radio paths, the main effect is observed as variations in the signal amplitude and the MOF-LOF working frequency band similarly to the critical frequency of the ionospheric F2 layer. Specifically, these parameters increase before the disturbance active phase, decrease during the active phase, and increase again after this phase. The propagation outside the great circle arc, the change in the propagation processes, and the HF radio noise behavior were also considered on these paths during storms (substorms). It is assumed that the storm (substorm) development onset can be predicted.     

Effect of eutrophication on molluscan community composition in the Lake Dianchi (China, Yunnan)

In this paper, three historical biodiversity datasets (from 1940s, 1980–1999 and 2000–2004) and results from the recent inventory are used to trace the long-term changes of the mollusks in the eutrophic Lake Dianchi. Comparison of the obtained results with those of earlier investigations performed during the period of 1940s and 1980–1999 as well as 2000–2004 showed that changes have occurred in the interval. There were 31 species and 2 sub-species recorded prior to the 1940s, but the species richness decreased from a high level of 83 species and 7 sub-species to 16 species and one sub-species from 1990s to the early of 21st century in lake body. Species from the genera of Kunmingia, Fenouilia, Paraprygula, Erhaia, Assiminea, Galba, Rhombuniopsis, Unionea and Aforpareysia were not found in Dianchi basin after 2000. The species from the genera Lithoglyphopsis, Tricula, Bithynia, Semisulcospira and Corbicula were only found in the springs and upstream rivers. Anoxia and the changing of substrates and fish species composition could explain why molluscan community composition changed in eutrophic Lake Dianchi. Additionally, the different sampling methods and ignore of the specific groups in earlier studies are cause for Sphaerium and Pisidium first found in our study. This study is first time to enlarge the investigation region to the Dianchi basin. Although some endemic species disappeared in the lake body, they still distribute in the springs and upstream rivers. The springs and upstream rivers are important refuges for mollusks.     

Joint inversion of the differential satellite interferometry and GPS data: A case study of Altai (Chuia) Earthquake of September 27, 2003

Based on the data of differential satellite interferometry, the field of displacements of the Earth’s surface in the line-of-sight direction is determined for the region of the Altai Earthquake that struck on September 27, 2003. The displacements are estimated for unforested areas of Chuia and the Kurai depressions, and for a part of their mountainous surroundings. In that part of the region where unwrapping of the data was possible, the amplitude of displacements amounts up to 150 cm for Chuia and 100 cm for the Kurai depressions. In order to locate the surface of the seismic rupture and to find the field of displacements on this surface, the method for the combined inversion of the displacements data, provided by satellite interferometry (the present work) and geodesy [Gol’din et al., 2005], is suggested and applied. The admissible range of the parameters of the rupture was specified from the seismology and seismotectonics data. The combined use of geodetic and satellite interferometry data makes the solution of the inverse problem more stable and yields a seismic momentum estimate, which is consistent with the seismological determinations. We discuss the possible contributions of various postseismic processes; in particular, based on analyzing the energy of the aftershocks, we assess the contribution of the postseismic creep to the displacements, determined from the interferometry and geodesy data, for different coseismic and postseismic time intervals.     

Effect of wind-current interaction on ocean response during Typhoon KAEMI(2006)

The Weather Research and Forecasting(WRF) model,the Princeton Ocean Model(POM),and the wave model(WAVEWATCH III) are used to develop a coupled atmosphere-wave-ocean model,which involves different physical processes including air-forcing,ocean feedback,wave-induced mixing and wave-current interaction.In this paper,typhoon KAEMI(2006) has been examined to investigate the effect of wind-current interaction on ocean response based on the coupled atmosphere-ocean-wave model,i.e.,considering the sea surface currents in the calculation of wind stress.The results show that the wind-current interaction has a noticeable impact on the simulation of 10 m-winds.The model involving the effect of the wind-current interaction can dramatically improve the typhoon prediction.The wind-current interaction prevents excessive momentum fluxes from being transferred into the upper ocean,which contributes to a much smaller turbulence kinetic energy(TKE),vertical diffusivity,and horizontal advection and diffusion.The Sea Surface Temperature(SST) cooling induced by the wind-current interaction during the initial stage of typhoon development is so minor that the typhoon intensity is not very sensitive to it.When the typhoon reaches its peak,its winds can disturb thermocline,and the cold water under the thermocline is pumped up.However,this cooling process is weakened by the wind-current interaction,as ocean feedback delays the decay of the typhoon.Meanwhile,the temperature below the depth of 30 m shows an inertial oscillation with a period about 40 hours(~17°N) when sudden strong winds beat on the ocean.Due to faster currents,the significant wave height decreases as ignoring the wind-current interaction,while this process has a very small effect on the dominant wave length.     

强化生态浮床原位修复技术对污染河流浮游动物群落结构的影响

对强化生态浮床原位修复技术修复南方重污染感潮河流过程中浮游动物的种群动态变化进行研究,探讨浮游动物群落结构变化特征与河流水质改善状况的相互关系.结果显示,经强化生态浮床处理后,重污染感潮河流水质得到改善,浮游动物的种类由修复工程实施前的5种增加到49种,且由单一耐污种转变为多种种类共存;示范区各月浮游动物个体丰度较对照...