31 research outputs found
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Vulnerability to climate change of managed stocks in the California Current large marine ecosystem
Introduction: Understanding how abundance, productivity and distribution of individual species may respond to climate change is a critical first step towards anticipating alterations in marine ecosystem structure and function, as well as developing strategies to adapt to the full range of potential changes. Methods: This study applies the NOAA (National Oceanic and Atmospheric Administration) Fisheries Climate Vulnerability Assessment method to 64 federally-managed species in the California Current Large Marine Ecosystem to assess their vulnerability to climate change, where vulnerability is a function of a speciesâ exposure to environmental change and its biological sensitivity to a set of environmental conditions, which includes components of its resiliency and adaptive capacity to respond to these new conditions. Results: Overall, two-thirds of the species were judged to have Moderate or greater vulnerability to climate change, and only one species was anticipated to have a positive response. Species classified as Highly or Very Highly vulnerable share one or more characteristics including: 1) having complex life histories that utilize a wide range of freshwater and marine habitats; 2) having habitat specialization, particularly for areas that are likely to experience increased hypoxia; 3) having long lifespans and low population growth rates; and/or 4) being of high commercial value combined with impacts from non-climate stressors such as anthropogenic habitat degradation. Species with Low or Moderate vulnerability are either habitat generalists, occupy deep-water habitats or are highly mobile and likely to shift their ranges. Discussion: As climate-related changes intensify, this work provides key information for both scientists and managers as they address the long-term sustainability of fisheries in the region. This information can inform near-term advice for prioritizing species-level data collection and research on climate impacts, help managers to determine when and where a precautionary approach might be warranted, in harvest or other management decisions, and help identify habitats or life history stages that might be especially effective to protect or restore
Physical and biological variables affecting seabird distributions during the upwelling season of the northern California Current
Author Posting. © The Authors, 2004. This is the author's version of the work. It is posted here by permission of Elsevier B. V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 52 (2005): 123-143, doi:10.1016/j.dsr2.2004.08.016.As a part of the GLOBEC-Northeast Pacific project, we investigated variation in the abundance of marine birds in the context of biological and physical habitat conditions in the northern portion of the California Current System (CCS) during cruises during the upwelling season 2000. Continuous surveys of seabirds were conducted simultaneously in June (onset of upwelling) and August (mature phase of upwelling) with ocean properties quantified using a towed, undulating vehicle and a multi-frequency bioacoustic instrument (38-420 kHz). Twelve species of seabirds contributed 99% of the total community density and biomass. Species composition and densities were similar to those recorded elsewhere in the CCS during earlier studies of the upwelling season. At a scale of 2-4 km, physical and biological oceanographic variables explained an average of 25% of the variation in the distributions and abundance of the 12 species. The most important explanatory variables (among 14 initially included in each multiple regression model) were distance to upwelling-derived frontal features (center and edge of coastal jet, and an abrupt, inshore temperature gradient), sea-surface salinity, acoustic backscatter representing various sizes of prey (smaller seabird species were associated with smaller prey and the reverse for larger seabird species), and chlorophyll concentration. We discuss the importance of these variables in the context of what factors may be that seabirds use to find food. The high seabird density in the Heceta Bank and Cape Blanco areas indicate them to be refuges contrasting the low seabird densities currently found in most other parts of the CCS, following decline during the recent warm regime of the Pacific Decadal Oscillation.Support from National Science Foundation Grant OCE-0001035, National Oceanic and Atmospheric Administration (NOAA)/Woods Hole Oceanographic Institution-CICOR Grant NA17RJ1223 is gratefully acknowledged
A Conceptual Model of Natural and Anthropogenic Drivers and Their Influence on the Prince William Sound, Alaska, Ecosystem
Prince William Sound (PWS) is a semi-enclosed fjord estuary on the coast of Alaska adjoining the northern Gulf of Alaska (GOA). PWS is highly productive and diverse, with primary productivity strongly coupled to nutrient dynamics driven by variability in the climate and oceanography of the GOA and North Pacific Ocean. The pelagic and nearshore primary productivity supports a complex and diverse trophic structure, including large populations of forage and large fish that support many species of marine birds and mammals. High intra-annual, inter-annual, and interdecadal variability in climatic and oceanographic processes as drives high variability in the biological populations. A risk-based conceptual ecosystem model (CEM) is presented describing the natural processes, anthropogenic drivers, and resultant stressors that affect PWS, including stressors caused by the Great Alaska Earthquake of 1964 and the Exxon Valdez oil spill of 1989. A trophodynamic model incorporating PWS valued ecosystem components is integrated into the CEM. By representing the relative strengths of driver/stressors/effects, the CEM graphically demonstrates the fundamental dynamics of the PWS ecosystem, the natural forces that control the ecological condition of the Sound, and the relative contribution of natural processes and human activities to the health of the ecosystem. The CEM illustrates the dominance of natural processes in shaping the structure and functioning of the GOA and PWS ecosystems
Long-Term Climate Forcing in Loggerhead Sea Turtle Nesting
The long-term variability of marine turtle populations remains poorly understood,
limiting science and management. Here we use basin-scale climate indices and
regional surface temperatures to estimate loggerhead sea turtle (Caretta
caretta) nesting at a variety of spatial and temporal scales.
Borrowing from fisheries research, our models investigate how oceanographic
processes influence juvenile recruitment and regulate population dynamics. This
novel approach finds local populations in the North Pacific and Northwest
Atlantic are regionally synchronized and strongly correlated to ocean
conditionsâsuch that climate models alone explain up to 88% of the
observed changes over the past several decades. In addition to its performance,
climate-based modeling also provides mechanistic forecasts of historical and
future population changes. Hindcasts in both regions indicate climatic
conditions may have been a factor in recent declines, but future forecasts are
mixed. Available climatic data suggests the Pacific population will be
significantly reduced by 2040, but indicates the Atlantic population may
increase substantially. These results do not exonerate anthropogenic impacts,
but highlight the significance of bottom-up oceanographic processes to marine
organisms. Future studies should consider environmental baselines in assessments
of marine turtle population variability and persistence
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State of the California Current 2012â13: No Such Thing as an "Average" Year
This report reviews the state of the California Current System (CCS) between winter 2012 and spring 2013, and includes observations from Washington State to Baja California. During 2012, large-scale climate modes indicated the CCS remained in a cool, productive phase present since 2007. The upwelling season was delayed north of 42ËN, but regions to the south, especially 33Ë to 36ËN, experienced average to above average upwelling that persisted throughout the summer. Contrary to the indication of high production suggested by the climate indices, chlorophyll observed from surveys
and remote sensing was below average along much of
the coast. As well, some members of the forage assemblages
along the coast experienced low abundances in
2012 surveys. Specifically, the concentrations of all lifestages
observed directly or from egg densities of Pacific
sardine, Sardinops sagax, and northern anchovy, Engraulis
mordax, were less than previous yearsâ survey estimates.
However, 2013 surveys and observations indicate an
increase in abundance of northern anchovy. During winter
2011/2012, the increased presence of northern copepod
species off northern California was consistent with
stronger southward transport. Krill and small-fraction
zooplankton abundances, where examined, were generally
above average. North of 42ËN, salps returned to
typical abundances in 2012 after greater observed concentrations
in 2010 and 2011. In contrast, salp abundance
off central and southern California increased after a
period of southward transport during winter 2011/2012.
Reproductive success of piscivorous Brandtâs cormorant,
Phalacrocorax penicillatus, was reduced while planktivorous
Cassinâs auklet, Ptychoramphus aleuticus was elevated.
Differences between the productivity of these two seabirds
may be related to the available forage assemblage observed in the surveys. California sea lion pups from
San Miguel Island were undernourished resulting in a
pup mortality event perhaps in response to changes in
forage availability. Limited biological data were available
for spring 2013, but strong winter upwelling coastwide
indicated an early spring transition, with the strong
upwelling persisting into early summer
Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic
This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic
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