A New Quantitative Bottom Sampler for Meiof auna     

Corey  Susan; Craib  J. S. 《ICES Journal of Marine Science》1966,30(3):346-353

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Effort distribution and catch patterns adjacent to temperate MPAs   总被引：7，自引：2，他引：7  

Murawski  Steven A.; Wigley  Susan E.; Fogarty  Michael J.; Rago  Paul J.; Mountain  David G. 《ICES Journal of Marine Science》2005,62(6):1150-1167

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Induction of chromosomal aberrations, sterility and mortality in irradiated polychaete worms     

Susan L. Anderson  Florence L. Harrison 《Marine environmental research》1985,17(2-4)

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High-resolution seafloor mapping using the DSL-120 sonar system: Quantitative assessment of sidescan and phase-bathymetry data from the Lucky Strike segment of the Mid-Atlantic Ridge     

Scheirer  Daniel S.  Fornari  Daniel J.  Humphris  Susan E.  Lerner  Steven 《Marine Geophysical Researches》2000,21(1-2):121-142

High-resolution, side-looking sonar data collected near the seafloor (100 m altitude) provide important structural and topographic information for defining the geological history and current tectonic framework of seafloor terrains. DSL-120 kHz sonar data collected in the rift valley of the Lucky Strike segment of the Mid-Atlantic Ridge near 37° N provide the ability to quantitatively assess the effective resolution limits of both the sidescan imagery and the computed phase-bathymetry of this sonar system. While the theoretical, vertical and horizontal pixel resolutions of the DSL-120 system are <1 m, statistical analysis of DSL-120 sonar data collected from the Lucky Strike segment indicates that the effective spatial resolution of features is 1–2 m for sidescan imagery and 4 m for phase-bathymetry in the seafloor terrain of the Mid-Atlantic Ridge rift valley. Comparison of multibeam bathymetry data collected at the sea-surface with deep-tow DSL-120 bathymetry indicates that depth differences are on the order of the resolution of the multibeam system (10–30 m). Much of this residual can be accounted for by navigational mismatches and the higher resolving ability of the DSL-120 data, which has a bathymetric footprint on the seafloor that is 20 times smaller than that of hull-mounted multibeam at these seafloor depths (2000 m). Comparison of DSL-120 bathymetry with itself on crossing lines indicates that residual depth values are ±20 m, with much of that variation being accounted for by navigational errors. A DSL-120 survey conducted in 1998 on the Juan de Fuca Ridge with better navigation and less complex seafloor terrain had residual depth values half those of the Lucky Strike survey. The quality of the bathymetry data varies as a function of position within the swath, with poorer data directly beneath the tow vehicle and also towards the swath edges.Variations in sidescan amplitude observed across the rift valley and on Lucky Strike Seamount correlate well with changes in seafloor roughness caused by transitions from sedimented seafloor to bare rock outcrops. Distinct changes in sonar backscatter amplitude were also observed between areas covered with hydrothermal pavement that grade into lava flows and the collapsed surface of the lava lake in the summit depression of Lucky Strike Seamount. Small features on the seafloor, including volcanic constructional features (e.g., small cones, haystacks, fissures and collapse features) and hydrothermal vent chimneys or mounds taller than 2 m and greater than 9 m² in surface area, can easily be resolved and mapped using this system. These features at Lucky Strike have been confirmed visually using the submersible Alvin, the remotely operated vehicle Jason, and the towed optical/acoustic mapping system Argo II.  相似文献   

Spatial Variation in the Structure of Kelp Forest Communities Along a Wave Exposure Gradient     

Christopher  Harrold  James  Watanabe Susan  Lisin 《Marine Ecology》1988,9(2):131-156

Abstract. Four sites were sampled in kelp (Macrocysiis pyrifera) forests occupying rocky bottom habitats along a wave exposure gradient in central California. Consistent betwecn-site differences were found in the three major structural elements - the surface canopy, the undcrstory assemblage, and the ground cover/turf assemblage - of kelp forest communities. Macrocysiis pyrifera was found at all four sites. Nereucyslis tuelkeana only at the most exposed site. The understory kelps Laminaria setchellii and Pterygopltora californica were also characteristic of exposed sites. Articulated coralline algae were more abundant at exposed sites than protected, while fleshy red algae showed the opposite pattern. All four study sites were located along 8.5 km of coastline, and thus were assumed to have available to them the same species pool for colonization. The substrate composition was the same and the amount of unconsolidated substrate was similar at all four sites. We suggest that exposure to wave-generated water motion, through its influence on the surface canopy and therefore on the amount of light reaching the bottom, is responsible for these between-site differences.  相似文献   

User participation and fishery management performance within the pacific fishery management council     

Susan S. Hanna 《Ocean & Coastal Management》1995,28(1-3)

Fish populations have the potential to contribute to the long-term economic and social benefit of humans, but to do so they must be managed in ways which maintain ecological health. There are many ways that management performance can be assessed, but four measures are particularly pertinent to sustainability: equity, stewardship, regulatory resilience, and efficiency. A key factor in management performance is the process by which management tools are developed and implemented. One approach that has been recommended to improve performance is to structure the management process around user participation. The paper analyzes three case studies of user participation in ad hoc processes of Pacific groundfish management: the development of a license limitation program; an inter-gear sablefish allocation; and the development of a sablefish individual quota (IQ) program. The case studies illustrate the role played by participation in contributing to the equity, stewardship, resilience, and efficiency of the management process. The effect of user participation was mixed in the three cases, depending on the history of participation, the structure and process of participation, on resource conditions and on the characteristics of the program under consideration. Participation can contribute positively to fishery management performance when there is a history of collective decision-making, the time line is slow enough to allow a full consideration of the issues, educational possibilities are pursued and the condition of the resource allows equitable compromises.  相似文献   

Light Requirements for Growth and Survival of Eelgrass (<Emphasis Type="Italic">Zostera marina</Emphasis> L.) in Pacific Northwest (USA) Estuaries     

Ronald M. Thom  Susan L. Southard  Amy B. Borde  Peter Stoltz 《Estuaries and Coasts》2008,31(5):969-980

We developed light requirements for eelgrass in the Pacific Northwest, USA, to evaluate the effects of short- and long-term reductions in irradiance reaching eelgrass, especially related to turbidity and overwater structures. Photosynthesis-irradiance experiments and depth distribution field studies indicated that eelgrass productivity was maximum at a photosynthetic photon flux density (PPFD) of about 350–550 μmol quanta m⁻² s⁻¹. Winter plants had approximately threefold greater net apparent primary productivity rate at the same irradiance as summer plants. Growth studies using artificial shading as well as field monitoring of light and eelgrass growth indicated that long-term survival required at least 3 mol quanta m⁻² day⁻¹ on average during spring and summer (i.e., May-September), and that growth was saturated above about 7 mol quanta m⁻² day⁻¹. We conclude that non-light-limited growth of eelgrass in the Pacific Northwest requires an average of at least 7 mol quanta m⁻² day⁻¹ during spring and summer and that long-term survival requires a minimum average of 3 mol quanta m⁻² day⁻¹.  相似文献   

Paleoecology of a Middle Wisconsin Deposit from Southern California     

R. Scott Anderson  Mitchell J. Power  Susan J. Smith  Kathleen Springer  Eric Scott 《Quaternary Research》2002,58(3):310

Analysis of a buried deposit in the Diamond Valley of southern California has revealed well-preserved pollen, wood, and diatom remains. Accelerator mass spectrometry dates of 41,200±2100 and 41,490±1380 ¹⁴C yr B.P. place this deposit in marine isotope stage 3. Diatoms suggest a shallow lacustrine environment. Pollen data suggest that several plant communities were present near the site, with grassland, scrub, chaparral, forest, and riparian communities represented. Comparison with modern pollen suggests similarities with montane forests in the nearby San Bernardino and San Jacinto ranges, indicating vegetation lowering by at least 900 m elevation and temperatures 4°–5°C cooler than today. An increase in high-elevation conifer pollen documents climatic cooling near the profile top. Early-profile diatoms are typical of warm water with high alkalinity and conductivity, whereas later diatoms suggest a higher flow regime and input of cooler water into the system. We suggest that the sequence is part of the cooling phase of an interstadial Dansgaard–Oeschger cycle. Records of the middle Wisconsin period are rare in southern California, but the Diamond Valley site is similar to records from Tulare Lake in the San Joaquin Valley and the ODP Site 893A record from Santa Barbara Basin. It is probable that the Diamond Valley assemblage is a local expression of a vegetation type widespread in the ranges and basins of southwestern California during the middle Wisconsin.  相似文献   

Characterisation of riparian woodlands and their potential water loss in the distal Okavango Delta, Botswana     

Susan Ringrose   《Applied geography (Sevenoaks, England)》2003,23(4):281-302

An analysis is undertaken to develop techniques to remotely sense relative evapotranspiration outputs in the distal Okavango Delta using enhanced thematic mapper and ground based techniques to help quantify water loss. Much of this work focuses on riparian woodlands which, especially in the distal portion of the Delta, are regarded as being significant in terms of groundwater removal by transpiration. This was confirmed as vegetation cover mapping led to the identification of two riparian classes which, by association with high resistivity aeromagnetic data, were found to be rooted in near surface fresh groundwater. This paper indicates that riparian trees which remain green year long, partly sustain their growth as a result of groundwater uptake. A comparison of frequently flooded and dry floodplains with distinct riparian zones was undertaken using spectral techniques (pixel radiance values and leaf water content indices) to determine whether flooding and lateral groundwater flow stimulated growth (and therefore transpiration rate) following dormancy. Results indicate a basic similarity between the two systems with mixed evidence of assumed leaf growth. Related phenological observations in the riparian zone of the dry floodplain show that renewal of leaf growth is primarily related to rainfall, not flood events in the distal Delta. The results of this work should help effect both surface and groundwater management in the vicinity of population centres in the distal Delta.  相似文献   

Controls on Fe reduction and mineral formation by a subsurface bacterium     

Susan Glasauer  Peter G Weidler  Terry J Beveridge 《Geochimica et cosmochimica acta》2003,67(7):1277-1288

The reductive dissolution of FeIII (hydr)oxides by dissimilatory iron-reducing bacteria (DIRB) could have a large impact on sediment genesis and Fe transport. If DIRB are able to reduce FeIII in minerals of high structural order to carry out anaerobic respiration, their range could encompass virtually every O₂-free environment containing FeIII and adequate conditions for cell growth. Previous studies have established that Shewanella putrefaciens CN32, a known DIRB, will reduce crystalline Fe oxides when initially grown at high densities in a nutrient-rich broth, conditions that poorly model the environments where CN32 is found. By contrast, we grew CN32 by batch culture solely in a minimal growth medium. The stringent conditions imposed by the growth method better represent the conditions that cells are likely to encounter in their natural habitat. Furthermore, the expression of reductases necessary to carry out dissimilatory Fe reduction depends on the method of growth. It was found that under anaerobic conditions CN32 reduced hydrous ferric oxide (HFO), a poorly crystalline FeIII mineral, and did not reduce suspensions containing 4 mM FeIII in the form of poorly ordered nanometer-sized goethite (α-FeOOH), well-ordered micron-sized goethite, or nanometer-sized hematite (α-Fe₂O₃) crystallites. Transmission electron microscopy (TEM) showed that all minerals but the micron-sized goethite attached extensively to the bacteria and appeared to penetrate the outer cellular membrane. In the treatment with HFO, new FeII and FeIII minerals formed during reduction of HFO-Fe in culture medium containing 4.0 mmol/L P_i (soluble inorganic P), as observed by TEM with energy-dispersive X-ray spectroscopy, selected area electron diffraction, and X-ray diffraction. The minerals included magnetite (Fe₃O₄), goethite, green rust, and vivianite [Fe₃(PO₄)₂ · 8H₂O]. Vivianite appeared to be the stable end product and the mean coherence length was influenced by the rate of FeIII reduction. When P_i was 0.4 mol/L under otherwise identical conditions, goethite was the only mineral observed to form, and less Fe²⁺ was produced overall. Hence, the ability of DIRB to reduce Fe (hydr)oxides may be limited when the bacteria are grown under nutrient-limited conditions, and the minerals that result depend on the vigor of FeIII reduction.  相似文献