Physical and biological factors influencing the spatial distribution of age-0 walleye pollock (Theragra chalcogramma) around the Pribilof Islands, Bering Sea     

Lorenzo Ciannelli  Richard D. Brodeur  Gordon L. Swartzman  Sigrid Salo 《Deep Sea Research Part II: Topical Studies in Oceanography》2002,49(26):6109-6126

The waters around the Pribilof Islands, in the southeast Bering Sea, are a main nursery area for age-0 pollock. Each summer, the islands are surrounded by a well-mixed inshore region, separated from a stratified offshore region by a frontal zone. To study the spatial distribution of age-0 pollock around this frontal structure in relation to physical and biological factors that are likely to influence it, such as advection, age-0 pollock feeding, and predation, samples were collected during September of four consecutive years, 1994–97, along two transects. Samples collected included water column hydrography and currents, acoustic backscatter, and groundfish predator density.Our analysis suggested that different mechanisms may be involved in controlling age-0 pollock distribution north and south of the islands. On the shelf area north of the islands, high age-0 pollock density was significantly associated with areas of high potential for growth only in years or portions of the frontal transect in which predator numbers were relatively low, indicating the importance of predation in controlling fish distribution in this area. In contrast, south of the islands, age-0 pollock distribution was associated more with prey availability, which appeared to be determined by vertical spatial overlap between predators and prey. Moreover, south of the islands, the stronger geostrophic currents, typical of the slope region, were more likely to affect the overall standing biomass of juvenile pollock, by constantly advecting fish away from the area.  相似文献   

The International Coral Reef Initiative: a seed from the Earth Summit tree which now bears fruit     

Richard B. Mieremet 《Ocean & Coastal Management》1995,29(1-3)

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Interactive computer graphics method for the combined interpretation of gravity and magnetic data     

Richard T. Haworth  Ian Wells 《Marine Geophysical Researches》1980,4(3):277-290

A program for computation of the gravity and magnetic anomalies associated with two-dimensional structures has been adapted for use in an interactive mode using a storage-screen CRT linked to a remote computer via standard telephone lines. This new program aids the user in developing a structural model that satisfies both magnetic and gravity observations. Examples are included to demonstrate the increased efficiency of interpretation using this low-cost graphics approach and to illustrate the detail of the model resulting from the compromise necessary to satisfy both potential-field data sets.  相似文献   

Hydrothermal Vent Geology and Biology at Earth’s Fastest Spreading Rates     

Richard N. Hey  Gary J. Massoth  Robert C. Vrijenhoek  Peter A. Rona  John Lupton  David A. Butterfield 《Marine Geophysical Researches》2006,27(2):137-153

Earth’s fastest present seafloor spreading occurs along the East Pacific Rise near 31°–32° S. Two of the major hydrothermal plume areas discovered during a 1998 multidisciplinary geophysical/hydrothermal investigation of these mid-ocean ridge axes were explored during a 1999 Alvin expedition. Both occur in recently eruptive areas where shallow collapse structures mark the neovolcanic axis. The 31° S vent area occurs in a broad linear zone of collapses and fractures coalescing into an axial summit trough. The 32° S vent area has been volcanically repaved by a more recent eruption, with non-linear collapses that have not yet coalesced. Both sites occur in highly inflated areas, near local inflation peaks, which is the best segment-scale predictor of hydrothermal activity at these superfast spreading rates (150 mm/yr).  相似文献   

Contaminant concentrations and toxicity of sea-surface microlayer near Los Angeles, California     

Jeffrey N. Cross  John T. Hardy  Jo Ellen Hose  G.Patrick Hershelman  Liam D. Antrim  Richard W. Gossett  Eric A. Crecelius 《Marine environmental research》1987,23(4)

Sea-surface microlayer samples were collected from six nearshore areas receiving different amounts of anthropogenic inputs. The samples were analyzed for selected trace metals, chlorinated hydrocarbons, and polycyclic aromatic hydrocarbons. The relative toxicities of the samples were determined with fish embryo bioassays.Contaminant concentrations generally increased from offshore to the inshore stations. Contaminant concentrations were several orders of magnitude higher in microlayer samples from the highly industrialized Los Angeles and Long Beach harbors compared to samples from a site 15km offshore. Microlayer samples from the inshore stations were significantly more toxic, and induced significantly more developmental abnormalities and chromosome aberrations, than samples from the offshore stations.  相似文献   

Vertical migration and mortality of benthos in dredged material: Part III—polychaeta     

Don Maurer  Richard T Keck  Jeff C Tinsman  Wayne A Leathem 《Marine environmental research》1982,6(1):49-68

The survival of benthic invertebrates from dredging and disposal activities is a major environmental concern in such projects. The purpose of the research described in this paper was to determine the ability of benthos (polychaetes, Scoloplos fragilis and Nereis succinea) to migrate vertically in natural and exotic sediments and to determine the survival of benthos when exposed to particular amounts of simulated dredged material.Mortalities generally increased with increased sediment depth, exotic sediment and burial time. Temperature also affected vertical migration and mortalities. These experiments, together with other experiments conducted by us and other workers, indicate that polychaetes in particular, and benthos in general, can survive dredging and disposal projects. Under certain conditions several major taxa (polychaetes, molluscs, crustaceans) can be expected to successfully recolonise disposal sites by vertical migration.  相似文献   

Spatial patterns of pollock and zooplankton distribution in the Pribilof Islands, Alaska nursery area and their relationship to pollock recruitment   总被引：2，自引：1，他引：2  

Swartzman  Gordon; Napp  Jeffrey; Brodeur  Richard; Winter  Andreas; Ciannelli  Lorenzo 《ICES Journal of Marine Science》2002,59(6):1167-1186

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Seabird numbers and prey consumption in the North Atlantic   总被引：1，自引：0，他引：1  

Barrett  Robert T.; Chapdelaine  Gilles; Anker-Nilssen  Tycho; Mosbech  Anders; Montevecchi  William A.; Reid  James B.; Veit  Richard R. 《ICES Journal of Marine Science》2006,63(6):1145-1158

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Post-Miocene stratigraphy and depositional environments of valley-fill sequences at the mouth of Tampa Bay, Florida     

Thomas W. Ferguson  Richard A. Davis  Jr.   《Marine Geology》2003,200(1-4):157-170

Post-Miocene sea-level low stands allowed rivers and karst processes to incise the exposed carbonate platform along the Gulf Coast of Florida. Few Miocene to mid-Pleistocene deposits survived erosion along the present coast except within incised valleys. Since their formation, these valleys have been filled and incised multiple times in response to sea-level changes. The thick sedimentary sequences underlying the mouth of Tampa Bay have been recorded as a range of depositional environments and multiple sea-level incursions and excursions during pre-Holocene time and subsequent to the accumulation of the Miocene carbonate sequences. Sediment analysis of cores collected from a north–south transect across the mouth of Tampa Bay has enabled the identification of lithofacies, ranging from well-sorted, quartz sand to dense, fossiliferous, phosphatic grainstone. These facies were deposited in freshwater, estuarine, and shallow, open marine environments. As a result of channel development and migration within the paleovalley, and cut-and-fill associated with individual transgressions and regressions, correlation of the lithofacies does not extend across the entire transect. Fining-upward sequences truncated by tidal ravinement surfaces that extend throughout the paleovalley can, however, be identified. Age determinations based on 14-C analysis, amino-acid racemization, and strontium isotope analysis dating of numerous samples yield ages of Miocene, Pliocene, early Pleistocene, and late Pleistocene, as well as Holocene for sequences that accumulated and were preserved in this valley-fill complex. Numerous inconsistencies in the stratigraphic organization of the age determinations indicate that there are bad dates, considerable reworking of shells that were dated, or both. For this reason as well as the lack of detailed correlation among the three relatively complete cores, it is not possible to place these strata in a sequence stratigraphic framework.  相似文献   

The influence of the Sabatayn Evaporites on the hydrocarbon prospectivity of the Eastern Shabwa Basin, Onshore Yemen     

T. Richard Seaborne 《Marine and Petroleum Geology》1996,13(8):963-972

The Shabwa Basin is the northeastern extension of the Marib-Al Jawf-Shabwa system of Mesozoic grabens, located onshore in the Republic of Yemen. An evaporitic sequence with an estimated maximum depositional thickness of 300 metres was deposited during the Tithonian. It is designated the Sabatayn Formation and exerts significant control on most of the play elements in the principal hydrocarbon play systems anticipated in the northeastern part of the basin. Migration of hydrocarbons from pre-salt source rocks into intra-and post-salt reservoirs is restricted by the evaporites. Localised heat flow perturbations introduced by the salt, increase the maturity of post-salt source rocks. Post and intra-salt reservoirs are structured by listric faulting on a salt detachment, salt pillowing due to post-depositional loading, by local salt dissolution and by late folding due to gravity sliding of the post-salt section on a salt detachment. Early dissolution and reprecipitation of salt is responsible for occlusion of porosity in intra-salt clastic reservoirs.  相似文献