Lipid biomarkers of deep-sea hydrothermal vent polychaetes—Alvinella pompejana, A. caudata, Paralvinella grasslei and Hesiolyra bergii     

Charles F. Phleger  Matthew M. Nelson  Ami K. Groce  S. Craig Cary  Kathryn Coyne  John A.E. Gibson  Peter D. Nichols 《Deep Sea Research Part I: Oceanographic Research Papers》2005,52(12):2333-2352

The lipid composition was determined for 5 species of polychaete annelids collected by the Deep Submergence Vehicle ALVIN from high temperature chimneys at the 2500 m depth hydrothermal vent field of the East Pacific Rise. These are the first lipid biomarker analyses reported for these hydrothermal vent polychaetes. Lipid content was low in all samples (1.6–35.9 mg g^–1 wet mass) and was dominated by polar lipid (78–90% of total lipid) with 8–19% sterol (ST), and very low storage lipid (triacylglycerol and wax ester). Total polyunsaturated fatty acids (PUFA) were moderately high (22–31% of total fatty acids (FA)) with extremely low or no docosahexaenoic acid (DHA, 22:6(n-3)). Eicosapentaenoic acid (EPA, 20:5(n-3)) levels were 5–6% in Alvinella pompejana and A. caudata and 10.3–13.7% in an errantiate polychaete (likely Hesionidae) and Hesiolyra bergii. There were greater PUFA and a greater EPA/AA (AA is arachidonic acid, 20:4(n-6)) ratio in the anterior versus the posterior half of A. pompejana, which may correlate to the strong temperature gradient reported in its tube. Total nonmethylene interrupted diunsaturated fatty acids (NMID) were 4–9% of total FA for most polychaete species and included several 20:2 and 22:2 components. The principal monounsaturated fatty acids (MUFA) included 18:1(n-7)c (14–19%), 16:1(n-7)c (2.6–10%) and 20:1(n-11)c (3–7% of total FA). These polychaete species may desaturate and elongate the bacterial-derived 18:1(n-7)c to obtain the essential FA EPA and AA. The major ST in the polychaetes is cholesterol (89–98% of total ST) with less cholesterol in the gut contents of A. pompejana. Other ST included 24-ethylcholesterol (1.5–5% of total ST) with lesser amounts of 24-methylenecholesterol, desmosterol, lathosterol, 24-methylcholesterol, 24-ethylcholesterol, and the stanols dehydrocholestanol and cholestanol. The high ST levels could play a role in thermal adaptation of membranes at the hydrothermal vent environment. Differences in the FA profiles separated the closely related species A. pompejana and A. caudata from Paralvinella grasslei, H. bergii, and the errantiate polychaete (likely Hesionidae).  相似文献   

Distribution and transport patterns of northern rock sole, Lepidopsetta polyxystra, larvae in the southeastern Bering Sea     

Jennifer A. Lanksbury  Kathryn L. Mier  Phyllis J. Stabeno 《Progress in Oceanography》2007,72(1):39-62

We report the size, abundance, and distribution (horizontal, vertical) of northern rock sole, Lepidopsetta polyxystra, larvae collected from ichthyoplankton surveys on the southeastern Bering Sea shelf near Unimak Island, in Unimak Pass, and in the Gulf of Alaska south of Unimak Island. The greatest abundances of larvae occurred within Unimak Pass and in the Bering Sea northeast of Unimak Island. Larvae were smaller and more abundant in 2002 than in 2003. Larval abundance and size varied with depth. Highest abundances were at depths of 10-30 m during the day, and larger fish appeared to migrate from below 20 m to 0-10 m at night. There was evidence of multiple spawning locales and larval dispersal pathways that were depth- and area-specific. Northern rock sole larvae spawned west of Unimak Pass along the Aleutian Islands may be transported northward by the Bering Slope Current. Larvae spawned in the Gulf of Alaska and advected through Unimak Pass are differentially dispersed, primarily to the middle and outer shelves along the 100 m and 200 m isobaths, or along the Alaska Peninsula. Larvae spawned along the Alaska Peninsula east of Unimak Island appear to have the greatest chance of being transported to nursery areas in the coastal domain. Dispersal of near-surface northern rock sole larvae in any of these locations is likely influenced by wind-driven advection, but below-surface (>10 m) northern rock sole larval transport is probably more affected by factors that modulate geostrophic flow rather than wind-driven surface currents.  相似文献   

Influence of Coupled Rossby Waves on Primary Productivity and Tuna Abundance in the Indian Ocean     

Warren B. White  Kathryn A. Gloersen  Francis Marsac  Yves M. Tourre 《Journal of Oceanography》2004,60(3):531-541

Interannual coupled Rossby waves in the extratropical Indian Ocean propagate westward in covarying pycnocline depth, sea surface temperature, and meridional surface wind anomalies from the west coast of Australia between 15°S and 35°S, taking 3–4 years to transit the interior ocean to Madagascar. In the interior subtropical gyre, where the tuna longline catch (TLC) mainly concerns two species (albacore and bigeye), these waves have been observed to affect year-to-year changes in catch, with wave crests (troughs) in the main pycnocline associated with high (low) TLC anomalies. This suggested that tuna longline catch is associated with the entrainment of nutrient-rich pycnocline water into the photic zone and a subsequent increase in primary productivity there. Here, this hypothesis is examined within the context of SeaWiFS chlorophyll concentration (CC). We find the situation the opposite of that expected, with wave crests (troughs) in the main pycnocline associated with low (high) CC anomalies averaged over the photic zone. These results are shown to be consistent with a model relating the anomalous CC tendency to upper-layer divergence in the wave, not unlike that relating surface slicks to upper-layer divergence in internal gravity waves. Thus, the connection between interannual coupled Rossby waves and TLC in the interior subtropical gyre does not appear to derive from wave-induced modulation of the pelagic food web. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Optically Stimulated Luminescence (OSL) dating of sand‐filled wedge structures and their fine‐grained host sediment from Jonzac,SW France     

Anja Guhl  Pascal Bertran  Christoph Zielhofer  Kathryn E. Fitzsimmons 《Boreas: An International Journal of Quaternary Research》2013,42(2):317-332

Two sand wedge structures and their host sediments, from Jonzac in SW France, were successfully dated using Optically Stimulated Luminescence (OSL) measurements on both small aliquots and single grains of quartz from the 180–212 μm size fraction. One of the sand wedges clearly contains primary infilling. However, grain‐size analysis and field observations do not clearly indicate whether the other feature represents a primary sand wedge or a composite sand wedge with primary and secondary infilling. OSL results and the geological setting justify using the Central Age Model (CAM) for the calculation of age estimates. Grain‐size analysis and detailed investigations of OSL results revealed the contamination of one sand wedge sample with host sediment. However, age calculation using the Finite Mixture Model (FMM) provided what is considered to be a reliable age estimate for the contaminated sample. The age estimates for all samples correspond to Marine Isotope Stage (MIS) 3. While fine‐grained sediments were deposited in the middle of MIS 3 (c. 43–55 ka), the sand wedges unexpectedly correspond to the end of this period (c. 33 ka) or the onset of MIS 2 (c. 27 ka). The sand wedges were probably formed during intense but short cold periods, possibly correlated with a Heinrich event (H2 and/or H3). The results help us to assess how effective luminescence dating is on sand wedges and the limitations involved in correlating sand wedge ages with Heinrich events, and contribute to the debate on the timing of cryogenic formation processes and the permafrost distribution in SW France.  相似文献   

Some effects of vertical resolution on modelling forced planetary waves with a time‐dependent model     

J.‐G. Desmarais  J. Derome 《大气与海洋》2013,51(2):212-225

Abstract

Previous studies by Nakamura (1976) and Kirkwood and Derome (1977) have shown that the use of a relatively low vertical resolution in a numerical model of the atmosphere can lead to a poor representation of the forced stationary planetary waves. In the present study the consequences of this result on short‐term numerical forecasts are investigated. This is done by performing forecast experiments using a low resolution linear β‐plane model that is initialized with data extracted from the steady forced solution of the high resolution (reference) version of the model. The deviation of the low resolution forecast from the initial state, which can be interpreted as the forecast error due to insufficient vertical resolution, is examined as a function of time.

It is shown that the short‐range forecast error is dominated by a westward propagating external mode and that in time some of the eastward moving internal modes gain in importance.  相似文献   

Avoiding deforestation in Panamanian protected areas: An analysis of protection effectiveness and implications for reducing emissions from deforestation and forest degradation     

Jordan S. Oestreicher  Karina Benessaiah  Maria C. Ruiz-Jaen  Sean Sloan  Kate Turner  Johanne Pelletier  Bruno Guay  Kathryn E. Clark  Dominique G. Roche  Manfred Meiners  Catherine Potvin 《Global Environmental Change》2009,19(2):279-291

Reducing greenhouse gas emissions from deforestation and forest degradation (REDD) is likely to be central to a post-Kyoto climate change mitigation agreement. As such, identifying conditions and factors that will shape the success or failure of a reduced deforestation scheme will provide important insights for policy planning. Given that protected areas (PAs) are a cornerstone in forest conservation, we draw on interviews and secondary data to analyze the effects of available PA resources, governance ability, the level of community involvement, and provincial deforestation rates on land-cover change in nine PAs in Panama. Our results illustrate that coupling surveillance measures with greater funding and strong governance are paramount to reducing deforestation. Alone, however, these factors are insufficient for forest protection. We argue that conservation approaches that complement effective surveillance with community participation and equitable benefit sharing will address the wider issues of leakage and permanence.  相似文献   

Science-based and stakeholder-driven marine protected area network planning: A successful case study from north central California     

Mary Gleason  Scott McCreary  Melissa Miller-Henson  John Ugoretz  Evan Fox  Matt Merrifield  Will McClintock  Paulo Serpa  Kathryn Hoffman 《Ocean & Coastal Management》2010,53(2):52-68

The planning process for California's Marine Life Protection Act in north central California represents a case study in the design of a regional component of a statewide network of marine protected areas (MPAs) for improved ecosystem protection. We describe enabling factors, such as a legislative mandate, political will, and adequate capacity and funding that fostered a successful planning process. We identify strategic principles that guided the design of a transparent public planning process that delivered regional MPA network proposals, which both met science guidelines and achieved a high level of support among stakeholders. We also describe key decision support elements (spatial data, planning tools, and scientific evaluation) that were essential for designing, evaluating, and refining alternative MPA network proposals and for informing decision-makers.  相似文献   

Practicing community geography in times of crisis     

Shannon  Jerry  Torres  Hannah  Mariner  Kathryn A.  Hawthorne  Timothy L. 《GeoJournal》2021,87(2):151-157

Community geography emphasizes the centrality of community engagement to socially transformative research. This introduction to a special issue of GeoJournal on community geography outlines how this growing subfield provides a model for collaborative action with the crises of our time, from white supremacy through climate change. As the co-editors of this special issue, we summarize the contents of these 14 articles, grouping them by the shared themes of power, institutional partnerships, pedagogy, and methods.

  相似文献   

The implications for paleodietary and paleoclimatic reconstructions of intrapopulation variability in the oxygen and carbon isotopes of teeth from modern feral horses     

Kathryn A. Hoppe  Sue Stuska 《Quaternary Research》2005,64(2):138-146

We analyzed the isotopic patterns found in the tooth enamel of modern feral horses from Shackleford Banks, North Carolina (USA), which has a temperate climate and supports primarily C₄ grasslands. Enamel δ¹³C values averaged −4.1‰ with a standard deviation (1σ) of 1.7‰, which corresponds to an average diet of 66 ± 12% C₄ plants. Our results differ from dietary reconstructions from 1978 to 1981, which found that horses consumed 91% C₄ plants. This suggests that horses have increased their consumption of C₃ forbs, likely as a result of the removal of cattle, sheep, and goats from the island. Shackleford surface waters had δ¹⁸O values that averaged −3.3 ± 0.5‰ and −1.3 ± 1.8‰ on the western and eastern ends of the island, respectively. Tooth enamel samples averaged 27.3 ± 1.5‰ and displayed the same range of δ¹⁸O values as surface waters. The variability of both δ¹⁸O and the δ¹³C values among individuals within this population demonstrates that horses from relatively homogenous temperate environments can display a wide range of isotopic values. Given the observed range of isotopic values for modern horses, we suggest that researchers use the mean values of multiple (≥9) equids when attempting to reconstruct average paleodiets and/or paleoenvironmental conditions.  相似文献   

Trace Element Determination by ICP-AES and ICP-MS: Developments and Applications Reported During 2004 and 2005     

Kathryn L. Linge 《Geostandards and Geoanalytical Research》2006,30(3):157-174

This review describes significant developments in trace element determination using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS) that were reported in 2004 and 2005. It focuses on the application of ICP techniques to geological and environmental samples; fundamental studies in ICP-MS and ICP-AES instrumentation are not included. The literature reviewed indicated that the majority of new publications concerned advances in ICP-MS analysis rather than ICP-AES. However, ICP-AES developments are still being published, particularly in the areas of sample preconcentration and sample introduction. The trend in increasing publication of developments in hyphenated speciation techniques looks set to persist as knowledge of elemental speciation becomes critical for many environmental studies. Collision or reactions cells were the most reported technique for spectral interference removal in ICP-MS, probably reflecting the growing adoption of cell instruments in laboratories during the last few years.  相似文献