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1.
We describe the hydrological structure of waters of the Persian Gulf and its seasonal variability according to the data of CTD surveys carried out in February–June 1992 in the course of the cruises of the NOAA R/VMt. Mitchell aimed at the analysis of the consequences of the ecological catastrophe caused by the spread of oil spots formed as a result of war operations in the Persian Gulf in 1991. Translated by Peter V. Malyshev and Dmitry V. Malyshev  相似文献   

2.
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3.
Occurrence of 130 species of decapod crustaceans was compared between the continental slope (200–2500 m) and the abyssal plain (2500–3840 m) of the Gulf of Mexico. We compiled records of these species from published literature and from the crustacean catalogue of the Marine Invertebrate Collection of Texas A&M University. Each species was scored as present or absent in each of 10 polygons that were defined by physiographic features of the sea floor. Using cluster analysis, we identified inherent patterns of species richness. A distinct faunal assemblage occurred in the Sigsbee Abyssal Plain. This deep plain was a potential “coldspot” in terms of the number of species in the basin, compared to a “hotspot” in the vicinity of De Soto Canyon. Polygons of the eastern upper slopes (i.e. calcareous substrate of western Florida) contained the most species that were not found elsewhere in the Gulf of Mexico. Using an inductive approach, we identified the following hypotheses: (1) most crustacean species of the deep Sigsbee Abyssal Plain occur in oceans world-wide, (2) overall, almost a quarter of the deep sea species in the Gulf of Mexico range from the western Atlantic (south of Cape Hatteras) to the Caribbean, and (3) the Gulf of Mexico is particularly rich in species of Munidopsis (25 species).  相似文献   

4.
Meso-scale spatial variability of coastal suprabenthic communities inhabiting muddy bottoms at 50–80 m depth in three gulfs of northern Sicily (Western Mediterranean) was here investigated. Although similar as concerns the hydrological and oceanographic conditions, the three areas, that encompass a large portion of the continental shelf (135 km), are characterized by different geo-morphological features. In addition, they are subjected to different trawl fishery pressures. The Gulf of Castellammare is a semi-enclosed bay, where the trawling activity has been banned since 1990. The Gulf of Termini Imerese and the Gulf of Sant’Agata are open areas, subjected to high trawl fishing intensity. In terms of density, gammarid amphipods showed differences among the three gulfs; in terms of biomass, cumaceans and amphipods were more abundant in the Gulf of Castellammare than in the other two areas. Multivariate analyses provided evidence for separation of suprabenthic assemblages between the Gulf of Castellammare and the other two gulfs. The Gulf of Castellammare seemed to host the most diversified and stable community according to α- and β-diversity indices. In the same way the low value of δ13C vs. δ15N correlation found in the gulf of Castellammare, which evidences the occurrence of several food sources, supports the idea of a higher stability in the semi-enclosed, trawl-ban area. In the other two areas δ13C vs. δ15N correlations were high, suggesting the existence of a pelagic source sustaining the suprabenthic communities. This is also confirmed by the lower δ13C concentrations found in suprabenthic species. Taking into account the homogeneous oceanographic conditions among gulfs, other factors, such as geo-morphology and trawling pressure should be involved in the observed differences among the three areas in terms of assemblage structure, diversity, and trophodynamics of suprabenthic communities.  相似文献   

5.
Active petroleum vents and slicks have been identified in the deep water of the northern Gulf of Mexico using numerous techniques. The occurrence and distribution of these petroleum vents are strongly influenced by the local geological framework—especially the presence of vertical migration pathways into shallow sediments. Oil and gas vents may be more useful for establishing the existence of petroleum generation on a regional scale and for evaluating the gross properties of oil migrating in the subsurface than for appraising the exploration value of individual prospects. Knowledge about petroleum venting in the deepwater Gulf of Mexico has proven to be an important element of the successful exploration activities there.  相似文献   

6.
While ocean acidification is a global issue, the severity of ecosystem effects is likely to vary considerably at regional scales. The lack of understanding of how biogeographically separated populations will respond to acidification hampers our ability to predict the future of vital ecosystems. Cold‐water corals are important drivers of biodiversity in ocean basins across the world and are considered one of the most vulnerable ecosystems to ocean acidification. We tested the short‐term physiological response of the cold‐water coral Lophelia pertusa to three pH treatments (pH = 7.9, 7.75 and 7.6) for Gulf of Mexico (USA) and Tisler Reef (Norway) populations, and found that reductions in seawater pH elicited contrasting responses. Gulf of Mexico corals exhibited reductions in net calcification, respiration and prey capture rates with decreasing pH. In contrast, Tisler Reef corals showed only slight reductions in net calcification rates under decreased pH conditions while significantly elevating respiration and capture rates. These differences are likely the result of environmental differences (depth, pH, food supply) between the two regions, invoking the potential for local adaptation or acclimatization to alter their response to global change. However, it is also possible that variations in the methodology used in the experiments contributed to the observed differences. Regardless, these results provide insights into the resilience of L. pertusa to ocean acidification as well as the potential influence of regional differences on the viability of species in future oceans.  相似文献   

7.
At the end of its useful life or because of a catastrophic event such as a hurricane, offshore pipelines are decommissioned, which normally involves cleaning the line by pigging or flushing, cutting the pipeline endpoints, and then plugging and burying each endpoint below the seabed or covering with a concrete mattress. The vast majority of decommissioned pipeline in the U.S. Gulf of Mexico is abandoned-in-place if the pipeline does not constitute a hazard to navigation, commercial fishing, or unduly interferes with other uses of the seabed. Using a unique data source from the Federal Energy Regulation Commission, decommissioning cost estimates for 28 gas export pipelines in the shallow water U.S. Gulf of Mexico between 1995 and 2015 are evaluated. The average inflation-adjusted pipeline decommissioning cost was $301,000 per mile ($187,000/km) and $47 per cubic foot ($1660 per cubic meter). Hurricane damaged and leaking pipelines are about three to four times more expensive on a unit cost basis than undamaged and non-leaking lines. No time trends or scale economies were observed. Primary cost drivers are identified and discussed.  相似文献   

8.
We quantify the similarity of the Gulf of Mexico mesopelagic fish fauna to that in adjacent oceanic regions, the Venezuelan and Colombian Basins of the Caribbean Sea and the North and South Sargasso Seas. The South Sargasso and Colombian are the least similar of the areas in terms of their faunal composition, and the Venezuelan and Colombian Basins are the most similar. The Gulf fauna lies somewhere in between, and is a composite of that in the Sargasso and Caribbean Seas. The Gulf of Mexico displays the greatest abundance, biomass and richness (S=140 species), and is an intermediate in evenness (J=0.66) and percent endemism (7.1%). Our findings support the view that the centrally located Gulf is an oceanic ecotone between the Atlantic Tropical and Subtropical faunal regions.  相似文献   

9.
The Gulf of Mexico Fishery Management Council determined that previous management of the grouper and tilefish fisheries in the northern Gulf of Mexico were not meeting management goals, and developed a catch shares program using individual fishing quotas (IFQs) beginning in January 2010 in order to more effectively manage these fisheries. An IFQ is a management method in which individual fishers and corporations are allocated the right to harvest a percentage of a fishery's total allowable catch, thus specifying how much of a particular species each fisher can harvest. This study makes use of a mail out survey to document the perceptions of fishers, seafood wholesalers, fisheries managers, and academics with an interest in the (northern) Gulf of Mexico grouper and tilefish IFQ program. While fishers, seafood dealers, fisheries managers, and academics all acknowledge that the IFQ program will create some problems, commercial fishers and dealers were far more skeptical of the alleged benefits of IFQs. Moreover, larger commercial operators were more inclined to agree with managers and academics that the IFQ program will produce several benefits for their operations and the fisheries. Some smaller operators believe that they will be driven to ignore the new rules or be forced out of business. In the future, the Gulf Council might do two things: put a bit more effort into making fishers aware of the potential benefits of IFQs, and develop alternatives with more flexibility perhaps working more closely with communities of fishers, who prize their independent way of life above all else.  相似文献   

10.
A. Zabanbark 《Oceanology》2006,46(4):557-563
With respect of its structure, the Gulf of Mexico basin is heterogeneous. The following individual basins and subbasins can be distinguished; (1) Mississippi-Louisiana; (2) Gulf Coast within the boundaries of Texas and New Mexico; (3) Mexican Gulf Coast and adjacent system of foredeeps; (4) Yucatan subbasin; (5) Cuba-Bahamas system of foredeeps. Regional seismic studies reveal a close relationship between salt movements and sedimentation. Salt bodies represent excellent cap rocks for hydrocarbon fluids. Anticline folds termed “turtle” structures forming a system of belts appear in the deep parts of the gulf. These structures host large reserves of hydrocarbons, which are concentrated in the Paleogene-Miocene turbidite reservoirs with a porosity approximately 30% overlain by excellent cap rocks (salt, clay) with permeability exceeding 3 darcy. Three productive zones are defined: (1) the folds of the Mississippi River fan; (2) the Perdido belt of anticline folds; (3) Florida. The Paleogene and Miocene-Pliocene-Pleistocene sediments developed on the continental slopes of the Gulf of Mexico basin are the areas most promising with respect to hydrocarbon deposits. On January 1, 2006, the offshore oil production was 53 million tons and the gas production 40 billion cubic meters. Total prospective oil and gas reserves are estimated to be 5.5 billion tons and 4.7 trillion cubic meters, of which over 50% of oil and 1/3 of gas are expected to be discovered on the continental slope.  相似文献   

11.
《Ocean & Coastal Management》2006,49(3-4):222-235
The Pacific shrimp fishery is the most economically important and ecologically impactful fishery in Mexico. Strong export markets have had a tremendous influence on the technological development and structure of this fishery. This article describes the historical development, current status, ecological impacts and management of the open ocean trawling component of the shrimp fishery in the Sonoran waters of the Gulf of California. We trace the economic factors influencing the development of the Mexican Pacific trawler-based shrimp fishery, with a focus on the port of Guaymas, Sonora, and summarize the events leading to the current overcapitalized and inefficient state of that fishery. The Sonoran shrimp fishery is characterized by high rates of by-catch and a decline in catch per boat trends. A review of economic factors indicates that the decision-making process in this fishery is driven by export markets and does not adequately consider the local ecosystems and fishing communities impacted by shrimp trawling. Management priorities for the fishery include fleet size reduction, habitat protection and alternative technology development. Successful management depends on the participation of powerful export–import companies, along side producers, government resource management agencies, NGOs and scientists. This paper describes recent efforts in collaborative management and calls for the expansion of these efforts.  相似文献   

12.
南海区海洋垃圾污染日益恶化对治理提出了严峻的挑战,公众既是海洋垃圾污染的直接受害者,也是海洋垃圾治理的直接受益者,更可以成为南海区海洋垃圾治理的参与者。文章阐述公众参与南海区海洋垃圾治理有助于从源头上控制南海区海洋垃圾污染状况、提升南海区海洋垃圾治理决策的科学性和针对性、降低政府治理南海区海洋垃圾的人力、物力成本的必要性,分析南海区海洋垃圾治理公众参与存在公众海洋垃圾治理参与意识薄弱、公众海洋垃圾治理参与方式不足、知情权和参与权未得到充分保障、海洋环保NGO的作用未充分发挥等问题,借鉴日本濑户内海、美国墨西哥湾、厦门五缘湾等国内外区域海洋垃圾治理公众参与的实践经验,提出培育参与意识和技能、开发新兴参与方式、建立健全政策法规、发展海洋环保NGO等完善公众参与治理的对策。  相似文献   

13.
The shared Torres Strait rock lobster (Panulirus ornatus) fishery provides important income for commercial and traditional fishers in Australia and Papua New Guinea. The lobster stock is first fished in Torres Strait by divers from both countries and then becomes vulnerable to Australian prawn trawlers, followed by Papua New Guinea trawlers during its annual breeding migration. Lobster catch sharing arrangements are governed by the Torres Strait Treaty ratified in 1985, but the sequential trawling of breeding lobsters has been controlled by bilateral agreements. A trawl ban was implemented in 1984 in both countries to conserve the breeding stock, but some trawling has been conducted in the Gulf of Papua since then and there is renewed interest in Papua New Guinea to resume trawling. To evaluate the impact of trawling migratory breeding lobsters on the lobster fishery, a model that combines a cohort depletion model with a stock recruitment relationship was developed in this study. The model showed that when the fishery is fully or over‐exploited by the dive fishery, trawling breeding lobsters would reduce both the spawning stock and the total catch of the fishery. The reduction in catch would increase with increasing fishing mortality. If trawling occurred on the Papua New Guinea side only, a redistribution of catch between Australia and Papua New Guinea would result in a small gain in catch for Papua New Guinea at the expense of the Australian dive fishery. But when fishing mortality reaches a certain level, any trawling in any country will incur catch loss to both countries. For the long‐term sustainability and maximum production of the fishery, regulations should be implemented in both countries under a co‐management scheme of a shared fish stock.  相似文献   

14.
Quantitative collections of tubeworm- and mussel-associated communities were obtained from 3 cold seep sites in the deep Gulf of Mexico: in Atwater Valley at 1890 m depth, in Alaminos Canyon at 2200 m depth, and from the Florida Escarpment at 3300 m depth. A total of 50 taxa of macro- and megafauna were collected including 2 species of siboglinid tubeworms and 3 species of bathymodiolin mussels. In general, the highest degree of similarity was between communities collected from the same site. Most of the dominant families at the well-characterized upper Louisiana slope seep sites of the Gulf of Mexico were present at the deep sites as well; however, there was little overlap at the species level between the upper and lower slope communities. One major difference in community structure between the upper and lower slope seeps was the dominance of the ophiuroid Ophioctenella acies in the deeper communities. The transition between upper and lower slope communities appears to occur between 1300 and 1700 m based on the number of shared species with the Barbados seeps at either end of this depth range. Seep communities of the deep Gulf of Mexico were more similar to the Barbados Accretionary Prism seep communities than they were to either the upper slope Gulf of Mexico or Blake Ridge communities based on numbers of shared species and Bray–Curtis similarity values among sites. The presence of shared species among these sites suggests that there is ongoing or recent exchange among these areas. An analysis of bathymodioline mussel phylogeography that includes new collections from the west coast of Africa is presented. This analysis also suggests recent exchange across the Atlantic equatorial belt from the Gulf of Mexico to the seeps of the West Nigerian margin.  相似文献   

15.
The overall effects of trawling on benthic habitats and their assemblages are dependent on the distribution and intensity of trawl effort. The benthic habitats of the Spencer Gulf prawn trawling grounds are subjected to known variable levels of trawling disturbance recorded from fisher's logbooks. These habitats have not been quantitatively investigated. The aim of the study was firstly to characterise the macro-faunal and -floral assemblages and secondly, to comparatively assess trawl impact by testing the null hypothesis of no differences between five sites exposed to different intensity of trawl effort. The distribution and abundance of benthic macro-fauna and -flora were studied at two sampling resolutions by using beam trawl sampling (10,000 m2) and underwater stereophotography (4.5 m2) at five sites with different levels of trawl disturbance (effort). The results showed that the Spencer Gulf prawn trawling grounds are characterised by sandy sediments with a low content of silt and clay, with the exception of one site with very fine gravel. Biomass, abundance and cover of macro-fauna and -flora were generally low throughout, but with large differences among sites. Biomass, abundance and cover were found to be negatively correlated to both trawl hours from 1994–1998 and during the period of study. ANOSIM and SIMPER analyses using biomass, abundance and percentage cover as variables showed significant differences between sites with eight species or taxonomic groups contributing more than 10% to the observed similarity within sites. The two northern sites were dominated by sponges and the bearded mussel, Trichomya hirsutus, and the southern hammer oyster, Malleus meridianus. Other species that contributed to the similarity within sites were the ascidian, Polycarpa viridis, mobile epifauna (the blue swimmer crab, Portunus pelagicus, and the western king prawn, Penaeus (Melicertus) latisulcatus) and demersal fish species (Degens leatherjacket, Thamnaconus degeni, and the Melbourne silver belly, Parequula melbournensis). Simpson's Index of Diversity (1 − λ) and species richness in the beam trawl samples were fairly even across all sites, but a significant effect of site was found in the stereophotographic transect samples. It was concluded that prawn trawling has a strong influence on the structure of the benthic habitats of the Spencer Gulf prawn fishing grounds highlighted by the magnitude of change and the strength of the gradient of effects. Confounding factors linked to the biophysical attributes of the sites are believed to be minor.  相似文献   

16.
The freshwater discharge from the Gulf of St. Lawrence and Hudson Bay accounts for more than 80% of the total freshwater discharge from eastern Canada and approximately 70% of the total discharge from the eastern seaboard of North America, from Baffin Island to Florida. If the Gulf of Mexico is included, the Gulf of St. Lawrence/Hudson Bay discharge is still more than half of the total.Both the Gulf of St. Lawrence and Hudson Bay have some distinctly estuarine characteristics and discharges of metals can be estimated using estuarine models. For Al, Mn, Fe, Co, Ni, Cu and Zn, the distributions can be described by simple, highly significant relationships with salinity. These regressions can be used in conjunction with knowledge of water discharges to estimate net metal inputs to the North Atlantic from these two systems.Most of the discharge from the Gulf of St. Lawrence flows along the Scotian Shelf to the Gulf of Maine. Metal-salinity relationships can also be used to estimate metal transports through this region for some metals. The applicability of this estuarine model, however, tends to break down as the oceanography becomes more complex and metal distributions are determined more by oceanic rather than estuarine processes.  相似文献   

17.
The magnetic properties from 200 trigger core-top and Van Veen grab sediment samples recovered from throughout the Gulf of Mexico have been analyzed and used to characterize sediment source and flow pattern distributions. Magnetic parameters included are anhysteretic remanent magnetism (ARM) and magnetic susceptibility (MS) measurements. Results from these measurements are compared to previously determined calcium carbonate percentages, and clay and hematite influx trajectories into the Gulf of Mexico for the same samples reported by Balsam and Beeson [Balsam, W.L. and Beeson, J.P., 2003. Sea-floor sediment distribution in the Gulf of Mexico, Deep-Sea Res. I, 50, 1421–1444.]. The ARM results give an estimate of magnetic grain size distributions, and by analogy, grain size distributions in general, whereas MS patterns show high detrital sediment accumulation zones within the Gulf. The dominant influx of modern high susceptibility sediment into the Gulf of Mexico appears to originate from the Red River, flow into Atchafalaya River Basin and out into the Gulf from Atchafalaya Bay, with significant additional contributions from the Mississippi River through the Southwest Pass of the Mississippi River Delta. This material then moves across the continental shelf and down through the Mississippi Canyon into the deep Gulf where it is redistributed at depths > 3600 m. The eastern shelf margins in the Gulf, offshore from Alabama and Florida, are accumulating calcite- or quartz-rich medium to fine-grained sediment that has a very low or diamagnetic MS signature. From the Louisiana to Texas Gulf coast margins, MS is moderate to high, suggesting a river influx of magnetic constituents from the volcanic fields in New Mexico, and from igneous and metamorphic sources in the Mississippi Basin. Offshore from western Mexico, the MS is high to moderate, but the Yucatan Shelf margin is characterized by low to diamagnetic MS values due to sediment dominated by calcite sands and oozes, a trend that continues to the east onto the West Florida Shelf. Additional measurements of samples collected in association with sites characterized by hydrocarbon seepage exhibit anomalously low MS values. The samples from the lower shelf and slope areas are typified by iron reduction by bacterial organisms in these samples. These results produce anomalous localized lows in the MS trends observed.  相似文献   

18.
During cruises 71-A-12 and 73-A-3 of the R/V “Alaminos” eighty-six samples of suspended matter at eleven near-bottom stations in the Gulf of Mexico and northwestern Caribbean Sea were collected, and simultaneously, values for light scattering were measured. Selected samples of the suspended matter were analyzed for particulate aluminum, silicon, iron, calcium, magnesium, organic carbon and inorganic carbon. The results indicate that a permanent but highly variable near-bottom nepheloid layer exists in the Gulf of Mexico but not in the northwestern Caribbean Sea. Average total-suspended loads in the Gulf of Mexico nepheloid layer are two times higher than in the clear water above the nepheloid layer.Since there is a significant increase in the alumino-silicate fraction and a corresponding decrease in the organic fraction of the suspended matter in the nepheloid layer relative to the overlying water, it appears that sediments are the most probable source of the increased concentrations of suspended matter in the nepheloid layer. This hypothesis is supported by X-ray diffraction analyses on the nepheloid material collected at one station which show the same mineral assemblages as the underlying sediments.Time studies over periods of one week and one and one-half years showed large total-suspended-matter variations which indicate that non steady-state processes, primarily vertical eddy diffusion and possibly advection, are controlling the distribution of suspended matter in the nepheloid layer.  相似文献   

19.
The first-generation University of Illinois gamma-ray transmission densitometer, designed for the in situ measurement of sediment bulk density, was modified by incorporating in the detector probe (1) an Americium-241 alpha particle pulser and an anti-walk gain stabilization control to maintain better temperature stability and (2) a small power supply and a IC preamplifier to eliminate the need for a high-voltage coaxial cable between the detector and external signal conditioning electronics package. This second-generation Lehigh University system has been successfully deployed since 1971 in routine use from ships and submersibles in the Atlantic and Pacific Oceans and the Gulf of Mexico. Results are presented of system operations to (1) measure bulk density over the range of 1.2–1.8 Mg/m3 in the Hudson Canyon, (2) penetrate 1.9 m into the seafloor in the San Diego trough and, (3) be lowered to a water depth of 3.6 km in the Gulf of Mexico.  相似文献   

20.
墨西哥及墨西哥湾盆地构造单元及其演化   总被引：2，自引：0，他引：2  
墨西哥及墨西哥湾盆地中生代以来可划分为两个一级构造单元,分别是墨西哥造山带和墨西哥湾盆地,进一步可划分二级构造单元6个,其中在墨西哥造山带划分了3个二级构造单元,分别是下加里福尼亚造山带、西马德雷—南马德雷岛弧带和东马德雷逆冲挤压带。在墨西哥湾盆地也划分了3个二级构造单元,分别是墨西哥湾盆地区、佛罗里达地块和尤卡坦地块。墨西哥造山带的形成是大洋板块和大陆板块相互作用的结果,但在不同构造单元上的表现不同。墨西哥湾盆地是一个中生代—新生代的裂谷盆地,包括内陆带、沿海带和洋壳带。根据墨西哥湾盆地构造地层幕将墨西哥湾盆地构造演化分为5个演化阶段,分别为晚三叠世到早侏罗世时期裂谷阶段,中侏罗世裂谷和地壳衰减阶段,晚侏罗世洋壳生成阶段,早白垩世下降阶段和晚白垩世至新生代陆源物质沉积和盐构造变形阶段。  相似文献   

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