共查询到20条相似文献，搜索用时 593 毫秒
1.
R. M. Stagg C. Robinson A. M. Mcintosh C. F. Moffat D. W. Bruno 《Marine environmental research》1998,46(1-5)
This paper describes the response of two fish species, the Atlantic salmon (Salmo salar) and the common dab (Limanda limanda) to the oil spilled from the Braer tanker which grounded on the southern tip of Shetland, Scotland, on 5 January 1993. Both the immediate sublethal effects and the long-term response to the oil which accumulated in sediments around the Shetland Isles, Scotland, are examined. The primary response measured was the induction of detoxification enzymes and the relationship of the levels or activities of these enzymes to the concentration and distribution of aromatic hydrocarbons measured in sediments, water and fish. The results show that, immediately following the spill, there was a marked induction of Cytochrome P4501A enzymes in salmon, indicative of exposure to bioavailable aromatics. In dab there was evidence of induction at some sites in January 1993 immediately following the spill but, subsequently, no induction has been observed in fish caught in the vicinity of Shetland despite the very high concentrations of oil measured in sediments at some locations. This would indicate that the polyaromatic hydrocarbons in these sediments are unlikely to be directly bioavailable to fish. The effect of the oil spill on hepatic pathology in dab was investigated and shows that pathology predictive of neoplasia, such as basophilic foci and vacuolation, were observed in fish from the most contaminated sites in 1994 but not in 1993. The incidence of this pathology appeared to correlate with the degree of contamination at the sites, but additional studies are required to establish whether this was a consequence of the initial impact and exposure from waterborne oil at the time of the spill or whether it was due to the continued exposure to oil from the sediments. 相似文献
2.
On rocky shores, the relative importance of abiotic and biotic processes that regulate community structure are thought to vary with levels of shore exposure. This can lead to characteristic features found on sheltered and exposed shores. This study identified differences in the population structure of mussels on exposed and sheltered rocky shores on Atlantic coasts of south-west Ireland. Direct interactions between epibiotic algae and their host mussels were also examined to test if potential effects varied with shore exposure. Mussel beds on sheltered shores were less dense and comprised larger mussels with greater rates of individual survival and growth than those on exposed shores. The results of a field experiment showed that algal epibionts had a negative effect on mussel survival on sheltered shores but not on exposed shores. Surprisingly, the presence of algal epibionts had no effect on mussel growth on either shore type. These findings contrast with those of previous studies. The effects of shore exposure and algal epibionts on mussels may be species-specific and may interact with other factors across different regions. This study shows that predictions of effects of exposure on mussel populations and their epibionts should only be based on specific experimental evidence and cannot be generalised across regions. 相似文献
3.
《Marine and Petroleum Geology》1988,5(2):182-192
The lower Cretaceous section of UK North Sea well 3/16-1, on the eastern flank of the Shetland Platform, drilled by Sovereign Oil & Gas plc, is dominated by marine ‘shelf-type’ limestones with a very low argillaceous content. In this respect it differs both from the typical open-sea coccolith-rich Chalk and from the argillaceous Cretaceous of the Viking Graben (the Cromer Knoll and Shetland Groups). Diagenesis has resulted in crystal overgrowths, corrosion, and development of very fine to coarsely crystalline void filling calcite. Cavities, of stromatactis type and the result of shell dissolution, are filled with radiaxial fibrous calcite. Porosity is mostly intercrystal with possible contributions from fractures and vugs.Hydrocarbon staining is confined to patches of void-filling calcite and partially cemented fractures. No oil staining was observed in the carbonate matrix. It therefore appears that oil migrated through the rock via fractures but was unable to penetrate the main fabric of the rock.The lithological and petrophysical characteristics of the interval are similar to the Chalk Group of Norwegian well 1/3-1. The thickness is considerably less in 3/16-1, probably as a result of deposition on a topographic high such as existed along the margins of the Viking Graben and the East Shetland Platform during the Cretaceous. 相似文献
4.
The Unst Basin is situated in the northern North Sea between the East Shetland Basin and the Shetland Isles. The basin is essentially a three-armed, Permo-Triassic fault-controlled basin containing up to 3600 m of red-beds. This is overlain by a westerly thickening Jurassic and early Cretaceous sequence, the stratigraphy of which is very similar to that of the East Shetland Basin. In particular, the Brent Group (140 m), Humber Group (685 m) and Cromer Knoll Group (300 m) are well represented.As a result of Laramide uplift of the area, the thick Upper Cretaceous and Palaeocene strata of the East Shetland Basin are absent from the Unst Basin. This uplift resulted in substantial erosion within the Unst Basin providing the major source for Palaeocene sands in the Viking Graben and the Faeroes Basin. Late Palaeocene and younger Tertiary strata transgress westwards across this erosion surface.Petroleum exploration within the basin culminated in the drilling of two exploration wells. These wells encountered potential reservoir and source rocks in the Jurassic section. However, geochemical analyses indicate these source rocks are immature for hydrocarbon generation within the Unst Basin. It is concluded that the Unst Basin has a low petroleum potential. 相似文献
5.
Ruth M. O'Riordan Jane Delany David McGrath Alan A. Myers Anne Marie Power Neil F. Ramsay Damaso Alvarez Teresa Cruz Federica G. Pannacciulli Pedro Range & Giulio Relini 《Marine Ecology》2001,22(4):307-322
Abstract. As part of a wider study on the settlement and recruitment of Chthamalus spp. in Europe, this study investigated whether chthamalid cyprids can be separated by length on a European scale. Variation in cyprid length with latitude and temporal variation at selected localities were also examined. The lengths of cyprids collected between 1996 – 1999 on nine rocky shores in Europe are reported. Elminius modestus cyprids were found only at Roscoff, NW France and could be distinguished due to their carapace shape and length. They showed a unimodal length distribution, measuring between 450 and 625 µm, with no variation in length between the two sampling dates (1997 and 1998). Based on carapace shape and length, the remaining cyprids in the collections were identified as one of three chthamalid species, Chthamalus montagui, Chthamalus stellatus or Euraphia depressa. Bimodal length distributions of chthamalid cyprids were seen on some shores, while others had a single small‐sized modal group (representing C. montagui on Atlantic shores and/or E. depressa in the Mediterranean) separated from a few distinctly larger cyprids (C. stellatus). Metamorphs collected simultaneously with cyprid collections were identified as C. stellatus or C. montagui, except at Roscoff, where E. modestus were also found. In southern Portugal, where all metamorphs collected were C. montagui and adult C. montagui were the dominant barnacles, most cyprids measured between 350 and 550 µm long and this size distribution coincides with the distribution expected for C. montagui. Cyprids collected on these four more southerly Portuguese shores had the same modal length class (475 µm) and this remained constant between successive years at Luz and Albufeira, Algarve. The smallest (350 µm long) wild chthamalid cyprids found were from southern Portugal and Italy. In Spain, France and Ireland the smallest chthamalid cyprid was 425 µm long. The results from the present study support the hypothesis that on Atlantic shores cyprids of C. montagui can be separated from those of C. stellatus based on size, although there is some variation in cyprid length with latitude as well as temporal variation at selected localities. 相似文献
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7.
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. 相似文献
8.
《African Journal of Marine Science》2013,35(1):759-770
Sandy beaches constitute nearly 46 per cent of the coastline between the Cape of Good Hope and the Orange River along the west coast of South Africa. In addition, shores of mixed sand and rock make up a further 24 per cent although these are not considered here. Sandy beaches are therefore the dominant shore type along the coastline, and most are subject to high wave energy. There are two main ecological beach types along the study coastline: those that receive a high input of organic matter in the form of stranded kelp and those that do not. Neither type appears to support large stocks of surf-zone phytoplankton, but despite this, even beaches receiving no stranded kelp bear high standing stocks of infauna. This fact may be related to the location of the beaches alongside a highly productive upwelling region. Existing ecological information on sandy beaches along the Benguela coastline is reviewed and integrated to form a composite picture of present understanding of these beaches. The definition of a sandy beach includes not only the sandy intertidal zone but also the surf zone and sand dunes associated with it. Sandy beaches are characterized by the absence of attached primary producers, although in some parts of the world primary production by surf-zone phytoplankton has been found to be important. Secondary production by the infauna usually depends on matter imported into the system, except on beaches supporting important stocks of surf-zone phytoplankton. Imported organic matter is retained by beach sediments which act as a physical sieve, filtering large quantities of water with each wave and tide. 相似文献
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The southern end of the Shackleton Fracture Zone is subducted below the South Shetland forearc, while the basal detachment of the forearc continues eastward of the Shackleton ridge as a thrust fault. The western boundary between the Antarctic/Scotia plates is located at the eastern margin of the Shackleton ridge, where an elongated depositional basin and a morphological trough delineates the contact. The boundary of the Antarctic/Scotia plates and the South Shetland forearc form a triple junction at the intersection of the Shackleton Fracture Zone with the trench, between these two plates, and an independent South Shetland block. 相似文献
11.
Effects of habitat complexity on cannibalism rates in European green crabs (Carcinus maenas Linnaeus, 1758) 
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下载免费PDF全文 The habitat in which predator–prey interactions take place may have a profound influence on the outcome of those interactions. Cannibalism is an intriguing form of predation whereby foraging by predators may contribute to the regulation of their own populations.This is particularly interesting in the case of invasive species, like the widely distributed European green crab (Carcinus maenas). This study explores how habitat complexity influences cannibalism rates in green crab populations of Prince Edward Island, Atlantic Canada. Both laboratory and field experiments were conducted to measure feeding rates by individual adult green crabs on a standard number of smaller conspecifics. In the laboratory, experimental treatments mimicked unstructured to increasingly structured habitats: water, sandy bottom, oyster shells, mussel shells, oyster shells with sandy bottom and mussel shells with sandy bottom. In those trials, adult green crabs consumed several times more juveniles on unstructured habitats than on the most structured ones, with a gradual decrease in predation rates across increasingly complex habitats. Field inclusion experiments used the same approach and were conducted in sandy bottoms, sandy bottoms with a layer of oyster shells and sandy bottoms with a layer of mussel shells. These trials showed similar patterns of decreasing feeding rates across increasingly complex habitats, but differences among treatments were not significant. These results support the idea that complex habitats have the potential to mediate predator–prey interactions, including adult–juvenile cannibalism in green crabs. 相似文献
12.
The Faroe-Shetland Channel, situated in the NE Atlantic, encompasses a number of different sediment types (habitats) as well as being subject to an unusual thermal regime. Our main objective was to assess variations in macrofaunal generic diversity and composition along two transects to gauge the relative influence of regional hydrography and local habitat heterogeneity. We found that generic richness and diversity on a West of Shetland (WoS) transect correlated most strongly with temperature range, whilst along a North of Shetland (NoS) transect, richness and diversity correlated negatively with sedimentary variables, notably total organic carbon. Macrofaunal composition at WoS is also strongly influenced by water temperature with specific genera ( e.g. Galathowenia positively associated with the temperature eigenvectors), whereas at NoS it is a combination of temperature, silt + clay fraction and total organic carbon that has an impact on composition ( e.g. Proclea and Pseudosphyrapus , showing a negative relationship with the temperature eigenvectors). Although the temperature regime exerts a strong control on regional ecology, local habitat heterogeneity remains a significant factor. 相似文献
13.
P. R. Boyle 《新西兰海洋与淡水研究杂志》2013,47(4):364-384
On several Auckland shores, a littoral chiton, Sypharochiton pelliserpentis (Quoy and Gaimard, 1835), was widely distributed and common. At Castor Bay it was the commonest chiton, and its density equalled or exceeded that of the commonest limpet (Cellana spp.) over most of the inter‐tidal range. Spot measurements of population density were made at other sites including exposed and sheltered shores. The smallest animals were restricted to the lower shore in pools or on areas of rock which were slow to drain. Exclusive of these small animals, the population structure was similar in pools and water‐filled crevices situated either high or low on the shore. This was also true for populations of animals from drained surfaces, but, at both shore levels, the population structure in the two micro‐habitats (pools and drained surfaces) was distinct. Single measurements of salinity in the very small volumes of water in which chitons were living gave a range of 13.3–45.8‰. In laboratory experiments at normal temperatures this species could survive these fluctuations for the maximum time possible between tides. Desiccation experiments, in which weight loss was expressed as a percentage of total water content, showed weight loss to depend on size. No significant differences in weight loss were found between populations from the two shore levels and the two micro‐habitats considered, though there were slight survival differences. Desiccation is probably an important factor influencing population structure, but loss of up to 75% of water content could be tolerated before 50% mortality occurred. Osmotic and desiccation stress evoked a characteristic behaviour pattern. 相似文献
14.
《Coastal Engineering》2005,52(6):535-563
The development, application and behaviour of a generic model of retreating soft rock (e.g. clay) shores is described. This represents a broad system, in coastal modelling terms, comprising shore platform, beach, tidal range, wave transformation, cliff and talus. The coast is divided into a series of representative cross-shore profiles, each of which is discretised into a column of elements. Erosion of a platform element at each timestep depends on its gradient. Material strength is dealt with as a calibration constant, wave forces are averaged over durations of a tide or hour and sediment transport is represented in bulk terms. Attention has been focussed on interaction between system parts and the emergence of system properties, in particular profile shape. This is allowed to develop towards dynamic equilibrium and is the principal means of model validation. The emergence of the profile shape is dominated by the distribution of wave scour by the tide and by interaction with a beach, if present. Because the model is process-based, it may be used to model the effects of climate change and engineering intervention. Yet it is also computationally inexpensive, so may be used to explore uncertainty through probabilistic application. The breadth of the included system, coupled with short run-times, enables predictions over timescales of decades, which we refer to as the Mesoscale. The model is used to explore the dynamics of retreating soft rock shore profiles and to predict future behaviour of a study site. 相似文献
15.
太平洋多金属结核中铁锰矿物分析及成因研究 总被引：12，自引：2，他引：10
铁锰矿物是大详多金属结核的重要组成,了解不同类型结核中主要铁锰矿物种类、形态、分布特点和结晶程度等,不仅有助于对锰矿物乃至多金属结核成因的研究,而且对选矿冶炼和资源的综合利用也具有现实意义.本文通过透射电子显微镜等多种手段综合分析与鉴定,指出多金属结核中主要铁锰矿物有钙锰矿、水羟锰矿、水钠锰矿、方锰矿、锰铁矿和针铁矿等.结晶程度普遍较差,钙锰矿结晶相对好于其他矿物,并在粗糙型结核中含量高,外层至核心含量稳定,变化小.水羟锰矿广为分布,但结晶差.铁矿物含量东区低于西区,结核外壳铁含量高于内核.锰矿物分布在叠层石柱体和纹层内,呈束状、纤维状和树枝状,与建造多金属结核的超微生物菌丝体形态一致.粗糙型结核是选冶的主要对象. 相似文献
16.
A sand-prone Middle Eocene sequence is recognized in three cored boreholes on the East Shetland Platform. Three lithostratigraphic divisions are recognized: Lower Sand Unit, Main Sand Unit and Upper Claystone Unit. The Lower Sand Unit is of fluvio-deltaic origin, occurring on the southern part of the East Shetland Platform. The Main Sand Unit represents the subsequent transgression of the delta. The unit comprises a set of highstand shelf systems tracts separated by glauconitic bands and reflected by palynological assemblage breaks. The presence of reworked palynofloras in sediments of late Middle Eocene age implies derivation of sediment from the north-west part of the East Shetland Platform. Although it is tempting to ascribe sea level changes to the sediment pattern, a tentative correlation with the Hampshire Basin only highlights the difficulties involved. 相似文献
17.
Five plant communities in Lake Rotoiti, North Island, New Zealand (38° 02’ S, 176° 24’ E) are described. In shallow water (0–2 m depth) partly protected from the prevailing westerly winds, some indigenous species form characteristic mounds. From 2 to 6 m depth the exotic macrophyte Lagarosiphon major (Ridley) Moss is the dominant and forms dense beds which appear to have completely replaced any native vegetation. Elodea canadensis Michx., a longer‐established exotic, may form a minor component of this zone, but may become the dominant species in water above and below the Lagarosiphon zone. Lagarosiphon appears to be primarily restricted to silty sand, but on pure silt areas it is replaced by Elodea and/or Nitella hookeri A. Braun. These zonations are probably static rather than successional. On underwater cliff faces and boulder shores a seasonal succession of algae was the major vegetation. Only filamentous cyanophytes grew within 1–2m of geothermal springs in the lake. 相似文献
18.
Morphometry of micrite particles in cretaceous microporous limestones of the Middle East: Influence on reservoir properties 总被引：2，自引：0，他引：2
Matthieu Deville de Periere Christophe DurletEmmanuelle Vennin Laurent LambertRaphael Bourillot Bruno CalineEmmanuelle Poli 《Marine and Petroleum Geology》2011,28(9):1727-1750
Microporosity may account for a significant part of the total porosity of Cretaceous limestone reservoirs of the Middle East. In these microporous facies porosity is moderate to excellent (up to 35%) while permeability is poor to moderate (up to 190 mD). Micritic limestones also may form dense layers with very low porosity and permeability values.Micritic samples were collected from three fields of the Habshan and Mishrif Formations, to examine the spatial relationship with their porosity, permeability and pore throat radius distributions. Two key parameters of the micritic particles are studied using scanning electron microscopy: their morphology (shape and inter-crystal contacts), and their crystallometry.Results reveal that micrite matrixes can be subdivided into three petrophysical classes. Class C (strictly microporous limestones with coarse punctic-to-partially coalescent micrites) is made up of coarse (>2 μm) polyhedral to rounded micritic crystals, it has good to excellent porosity (8-28%), poor to moderate permeability (0.2-190 mD) and a mean pore threshold radius of more than 0.5 μm. The class C is usually observed in rudist shoal facies where relatively high hydrodynamic energy disfavoured deposition of the finer micritic crystals. It also developed within meteoric leaching intervals below exposure surfaces. Class F (strictly microporous limestones with fine punctic-to-partially coalescent micrites) is composed of fine (<2 μm) polyhedral to rounded micrites with poor to excellent porosity (3-35%), but permeability values of less than 10 mD and a mean pore threshold radius of less than 0.5 μm. It is mostly observed in sediments deposited in a low energy muddy inner platform setting. Class D (strictly microporous mud-dominated facies with compact anhedral to fused dense micrites) comprises subhedral to anhedral crystals with sutured contacts forming a dense matrix. It has very low porosity and permeability. Class D is only found in low energy muddy inner platform facies and forms inter-reservoir or caps rock layers in close association with stylolites and clay contents that usually exceed 10%. 相似文献
19.
The deep‐sea floor is increasingly subject to anthropogenic impacts. Consequently, there are increasing efforts to develop appropriate management strategies. Species‐level indicators and assessments are hampered in the deep sea by the high proportion of unknown species routinely encountered. If environmental management is to keep pace with exploitation, alternative approaches including higher taxon surrogacy (taxonomic sufficiency) must be considered. Here we compare genus‐ and species‐level studies of the diversity and ecology of deep‐sea macrobenthos on the West Shetland Slope (NE Atlantic). This is an environmentally complex region that encompasses a biogeographic transition from temperate North Atlantic to Arctic conditions, and so may be particularly challenging for any general relationship between species‐ and genus‐level analyses. We ask two questions: (i) does genus diversity reflect species diversity and (ii) does genus‐level ecology reflect species‐level ecology? We conclude that among the West Shetland Slope macrobenthos: (i) genus‐level α‐ and β‐diversity measures are highly correlated with and good predictors of their species‐level equivalents and (ii) that their ecology is very well described by genus‐level data. We further note that, given the complexity of the West Shetland Slope environment, it may be reasonable to expect these conclusions to hold in other deep‐sea environments. 相似文献