272 research outputs found
Two coastal upwelling domains in the northern California Current system
A pair of hydrographic sections, one north and one south of Cape Blanco at 42.9N, was sampled in five summers (1998–2000 and 2002–2003). The NH line at 44.6N lies about 130 km south of the Columbia River, and spans a relatively wide shelf off Newport, Oregon. The CR line at 41.9N off Crescent City, California, lies 300 km farther south and spans a narrower shelf. Summer winds are predominantly southward in both locations but the southward winds are stronger on the CR line. Sampling included CTD/rosette casts (to measure temperature, salinity, dissolved oxygen, nutrients, chlorophyll), zooplankton net tows and continuous operation of an Acoustic Doppler Current Profiler. We summarize and compare July-August observations from the two locations. We find significant summer-season differences in the coastal upwelling domains north and south of Cape Blanco. Compared to the domain off Newport, the domain off Crescent City has a more saline, cooler, denser and thicker surface mixed layer, a wider coastal zone inshore of the upwelling front and jet, higher nutrient concentrations in the photic zone and higher phytoplankton biomass. The southward coastal jet lies near the coast (about 20–30 km offshore, over the shelf) on the NH line, but far from shore (about 120 km) on the CR line; a weak secondary jet lies near the shelf-break (35 km from shore) off Crescent City. Phytoplankton tend to be light-limited on the CR line and nutrient-limited on the NH line. Copepod biomass is high (15 mg C m−3) inshore of the mid-shelf on both NH and CR lines, and is also high in the core of the coastal jet off Crescent City. The CR line shows evidence of deep chlorophyll pockets that have been subducted from the surface layer. We attribute these significant differences to stronger mean southward wind stress over the southern domain, to strong small-scale wind stress curl in the lee of Cape Blanco, and to the reduced influence of the Columbia River discharge in this region
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Benthic-Pelagic Links and Rocky Intertidal Communities: Bottom-Up Effects on Top-Down Control?
Insight into the dependence of benthic communities on biological and physical processes in nearshore pelagic environments, long considered a ``black box,'' has eluded ecologists. In rocky intertidal communities at Oregon coastal sites 80 km apart, differences in abundance of sessile invertebrates, herbivores, carnivores, and macrophytes in the low zone were not readily explained by local scale differences in hydrodynamic or physical conditions (wave forces, surge flow, or air temperature during low tide). Field experiments employing predator and herbivore manipulations and prey transplants suggested top-down (predation, grazing) processes varied positively with bottom-up processes (growth of filter-feeders, prey recruitment), but the basis for these differences was unknown. Shore-based sampling revealed that between-site differences were associated with nearshore oceanographic conditions, including phytoplankton concentration and productivity, particulates, and water temperature during upwelling. Further, samples taken at 19 sites along 380 km of coastline suggested that the differences documented between two sites reflect broader scale gradients of phytoplankton concentration. Among several alternative explanations, a coastal hydrodynamics hypothesis, reflecting mesoscale (tens to hundreds of kilometers) variation in the interaction between offshore currents and winds and continental shelf bathymetry, was inferred to be the primary underlying cause. Satellite imagery and offshore chlorophyll-a samples are consistent with the postulated mechanism. Our results suggest that benthic community dynamics can be coupled to pelagic ecosystems by both trophic and transport linkages.KEYWORDS: scale, productivity, currents, upwelling, community structureThis is the publisher’s final pdf. The published article is copyrighted by the National Academy of Sciences of the United States of America and can be found at: http://www.pnas.org
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Preliminary Cruise Report, W0408D and W0409A, R/V WECOMA, 30 August – 3 September and 7-9 September 2004 : GLOBEC NEP Long-Term Observations off Oregon
PURPOSE (W0408D): To determine physical, plankton and nutrient/chemical conditions over the
continental margin for climate change studies in NE Pacific. In particular, to make CTD and CTD/
rosette and net tow stations along 3 lines (off Newport, Strawberry Hill and Heceta Head, OR.), and
to make continuous observations of currents using ADCP and of surface-layer temperature, salinity
and fluorescence by means of ship’s thru-flo system
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Upper ocean water properties and currents along paired sections in the Northern California Current, September 1999-2003
As part of the U. S. GLOBEC NorthEast Pacific
Program we made repeated seasonal hydrographic surveys in
the northern California Current system between July
1997 and September 2003. These surveys included sampling
along a pair of hydrographic sections, one north (at 44.6ºN)
and one south (at 41.9ºN) of Cape Blanco (Figure 1) in
September of five years (1999-2003). The coastal upwelling
associated with the California Current experiences maximum
upwelling during summer, and usually continues through much
of September; upwelling is usually stronger at 42ºN than at
45ºN. One purpose of this report is to show
differences and similarities between the coastal upwelling
domains north and south of Cape Blanco. We present graphical
summaries of the physical oceanographic and biochemical
observations along both sections, principally in the form of
zonal sections (0-160 km from shore, 0-150 m depth). We also
show offshore profiles of a few selected properties, and some
characteristic diagrams (T-S, oxygen-S, etc.). Similar reports
showing results for mid-summer and for spring have already
been published (Fleischbein et al., 2005a, b)
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Genomic Profiling of Childhood Tumor Patient-Derived Xenograft Models to Enable Rational Clinical Trial Design.
Accelerating cures for children with cancer remains an immediate challenge as a result of extensive oncogenic heterogeneity between and within histologies, distinct molecular mechanisms evolving between diagnosis and relapsed disease, and limited therapeutic options. To systematically prioritize and rationally test novel agents in preclinical murine models, researchers within the Pediatric Preclinical Testing Consortium are continuously developing patient-derived xenografts (PDXs)-many of which are refractory to current standard-of-care treatments-from high-risk childhood cancers. Here, we genomically characterize 261 PDX models from 37 unique pediatric cancers; demonstrate faithful recapitulation of histologies and subtypes; and refine our understanding of relapsed disease. In addition, we use expression signatures to classify tumors for TP53 and NF1 pathway inactivation. We anticipate that these data will serve as a resource for pediatric oncology drug development and will guide rational clinical trial design for children with cancer
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Preliminary Cruise Report, W0007A, R/V WECOMA, 7-13 July 2000 : GLOBEC/ENSO Long-Term Observations off Oregon
PURPOSE: To determine physical, plankton and nutrient/chemical conditions over the continental
margin for climate change studies in NE Pacific. In particular, to make CTD and CTD/rosette and net
tow stations along 5 lines (off Newport, Heceta Head, Coos Bay, the Rogue River, OR. and Crescent
City, CA., to make continuous bio-acoustic observations between the 50-500m. isobaths along the 5
lines, to deploy drifters at selected locations on the Newport line, and to make continuous observations
of currents using ADCP and of surface-layer temperature, salinity and fluorescence by means
of ship’s thru-flo system
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Preliminary Cruise Report, W0009A Leg 1, R/V WECOMA, 7-12 September 2000 : GLOBEC/ENSO Long-Term Observations off Oregon
PURPOSE: To determine physical, plankton and nutrient/chemical conditions over the continental
margin for climate change studies in NE Pacific. In particular, to make CTD and CTD/rosette and net
tow stations along 5 lines (off Newport, Heceta Head, Coos Bay, the Rogue River, OR. and Crescent
City, CA.), to make continuous bio-acoustic observations between the 50-500m. isobaths along the 5
lines, to deploy drifters at selected locations on the Newport line, and to make continuous observations
of currents using ADCP and of surface-layer temperature, salinity and fluorescence by means
of ship’s thru-flo system
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Preliminary Cruise Report, W9911A, R/V WECOMA, 3-5 November 1999 : GLOBEC/ENSO Long-Term Observations off Oregon
PURPOSE: To determine physical, plankton and nutrient/chemical conditions over the continental
margin for climate change studies in NE Pacific. In particular, to make CTD and CTD/rosette and net
tow stations along one lines off Newport, OR, and to make continuous observations of currents using ADCP and of surface-layer temperature, salinity and fluorescence by means of ship’s thru-flo system
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Preliminary Cruise Report, W0002A, R/V WECOMA, 1-3 February 2000 : GLOBEC/ENSO Long-Term Observations off Oregon
PURPOSE: To determine physical, plankton and nutrient/chemical conditions over the continental
margin for climate change studies in NE Pacific. In particular, to make CTD and CTD/rosette and net
tow stations along one line off Newport, OR, and to make continuous observations of currents using
ADCP and of surface-layer temperature, salinity and fluorescence by means of ship’s thru-flo system
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