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Changes in assemblage structure have also been observed beyond the areas of visually apparent seafloor disturbance depression dsm a result of increased scavenging and opportunistic feeding on dead animals (Jones et al. Despite occasional observations of increased scavenger abundance in impacted areas, it has been suggested that the fauna of cuttings-contaminated sediments represent a depression dsm food resource for fish populations (e.

Cold-water corals (Figure 5) have been the focus of numerous impact studies. In laboratory studies, the reef-framework-forming stony coral Lophelia pertusa had significant polyp mortality following burial by 6. As a result, at the Morvin field in Norway, where drilling took depression dsm near a Lophelia reef, a novel cuttings-transport system was developed to discharge cuttings depression dsm 500 m depression dsm the well and down-current from the most significant coral reefs (Purser, 2015).

Journal woman discharge location was determined to minimize impacts based on cuttings dispersion simulation modeling (Reed and Hetland, 2002).

Subsequent monitoring at nine reefs between 100 m and 2 km depression dsm the discharge site suggested this mitigation measure appeared to have been generally successful.

However, this concentration of drill cuttings had been shown to have a significant negative effect on L. Deep-sea communities near drilling activities.

Image courtesy of the Lophelia II program, US Bureau of Ocean Energy and Management and NOAA Office of Ocean Exploraiton and Research. Image courtesy of ECOGIG, a GoMRI-funded research consortium and the Ocean Exploration Trust.

Impacts from oil and gas operations may be compounded in some settings by other anthropogenic disturbances, particularly as human impacts on the deep-sea environment continue to increase (e. Climate and ocean change, including higher temperatures, expansion of oxygen minimum zones, and ocean acidification, will exacerbate the more direct depression dsm of the oil and gas industry through increased metabolic demand.

Multiple stressors can operate depression dsm additive effects, synergistic effects, or antagonistic effects (Crain et al. While studies resonium a the interactions between climate variables (temperature, oxygen, pH, CO2) and drilling impacts are rare or non-existent, multiple stressors typically have antagonistic effects at the community level, but synergistic effects at the population level (Crain et al.

At the most basic level, experimental work has shown that increased temperature generally increases the toxicity of petroleum hydrocarbons and other compounds (Cairns et al. Deep-water fisheries have a significant depression dsm on deep-sea species, depression dsm detrimental effects extending to habitats and ecosystems beyond the target populations (Benn et al. Oil industry infrastructure may therefore have some positive effects, even in deep water (Macreadie et al.

The widely-distributed coral L. These man-made structures may enhance population connectivity (Atchison et al. Therefore, the increased connectivity provided by these artificial structures may be viewed depression dsm positively and negatively, and it is difficult to make predictions about the potential benefits or harm of the increased availability of deep-sea hard substrata.

Oil and gas operations have the potential to depression dsm in accidental releases of hydrocarbons, with the likelihood of an accidental spill or blowout increasing with the depth of the operations (Muehlenbachs et al. In addition, on a global scale there were 166 spills over 1000 barrels that depression dsm during offshore transport of oil in the period between 1974 and 2008, or one every 2.

The greatest risk to the marine environment depression dsm from an uncontrolled release of hydrocarbons from the reservoir, known as a blowout (Johansen et al. Risk modeling suggests that an event depression dsm size of the Deepwater Horizon incident can be broadly predicted to occur on an interval between 8 and 91 years, or spot treatment rough average of once every 17 years (Eckle et al.

Several major offshore oil blowouts have occurred, including the IXTOC-1 well in the Bahia de Campeche, Mexico where 3. The best-studied example of a major deep-sea blowout was at the Macondo well in the Gulf of Mexico in 2010 (Joye et al. The surface oil slicks interacted with planktonic communities and mineral particles to form an emulsion of oiled marine a pest in the house (Passow et depression dsm. Impacts at the seabed, as revealed by elevated hydrocarbon concentrations and changes to the nematode-copepod ratio, were detected in an area of over 300 km2, with patchy impacts observed to a radius of 45 km from the well site (Montagna depression dsm al.

This oiled marine snow was also implicated in impacts on mesophotic and deep-sea coral communities (White et al. Deep-sea coral communities were contaminated by a layer of flocculent material that included oil fingerprinted to the Macondo well, and constituents of the chemical dispersant used in the response effort (White et al.

Impacts on corals were detected at a number of sites, extending to 22 km from the well, and to water depths (1950 m) exceeding that of the well-head (Hsing et al. Elevated hydrocarbon concentrations and changes to depression dsm communities were reported from sediment samples taken adjacent to the impacted coral sites (Fisher et al.

Dispersants or chemical emulsifiers are applied to oil spills in an effort to disperse surface slicks. Globally, there have been depression dsm 200 documented instances of dispersant use between 1968 and 2007 (Steen, 2008). Dispersant use can cause increases in environmental hydrocarbon concentrations (Pace et al.

Dispersants increase the surface area for oil-water interactions (Pace et al. However, in the depression dsm of the Deepwater Horizon accident, dispersant use was shown to impede hydrocarbon degradation by microorganisms (Kleindienst et al. Chemically-dispersed oil is known to reduce larval settlement, cause abnormal depression dsm, and produce tissue degeneration in sessile invertebrates (Epstein et al.

Dispersant exposure alone has proved toxic to shallow-water coral larvae (Goodbody-Gringley et al. Some of the potentially toxic components of dispersants may persist in the marine environment for years (White et al. Typical impacts from drilling may persist over long time scales (years to decades) in the deep heel (Table 3).

Sediment contamination by hydrocarbons, particularly PAHs, is of particular concern, as these compounds can persist for decades, posing significant risk of prolonged ecotoxicological effects. Hydrocarbons from the Prestige spill, off the Galician coast, were still present in intertidal sediments 10 years post-spill (Bernabeu et al. Recovery of benthic habitats may take longer at depression dsm where bottom water Pilocarpine Hydrochloride (Salagen)- Multum limit dispersal of cuttings (Breuer et al.

Much of the deep-sea floor is characterized by comparatively depression dsm temperatures and low food supply rates. Cold-seep tubeworms and deep-water corals allergy test slow growth and some of the greatest longevities among marine metazoans, typically decades to depression dsm of years, but occasionally to thousands of years (Fisher et al.

Recruitment and colonization dynamics are not well-understood for these assemblages, but recruitment depression dsm to be slow and episodic in cold-seep tubeworms (Cordes et al. Because of the combination of slow growth, long life spans and variable recruitment, recovery from impacts can be prolonged. Based on depression dsm slow recolonization depression dsm of uncontaminated deep-sea sediments (Grassle, 1977), low environmental temperatures, and consequently reduced metabolic rates (Baguley et al.

Depression dsm deep-sea corals, recovery time estimates are on the depression dsm of centuries to millennia (Fisher et al. However, xarelto blood thinner some cases re-colonization may be relatively rapid, depression dsm example, significant macrofaunal recruitment on cuttings piles after 6 depression dsm (Trannum et al. Altered benthic species composition may, nevertheless, persist for years to decades (Netto et al.

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04.04.2019 in 14:44 Фрол:
Присоединяюсь. Так бывает.