287 research outputs found
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Potential Effects of Management on Caspian Tern Hydroprogne caspia Predation on Juvenile Salmonids at a Colony in San Francisco Bay, California
San Francisco Bay is a proposed relocation site for some of the Caspian terns Hydroprogne caspia currently nesting at the world's largest colony for the species in the Columbia River estuary and consuming salmonids listed under the U. S. Endangered Species Act (ESA). However, several runs of salmonids listed under the ESA occur in San Francisco Bay and managers are concerned that increased Caspian tern predation may pose a threat to the recovery of these fish. We used a bioenergetics modeling approach, employing estimates of tern energy requirements and proportions of energy supplied by various prey types, to estimate the consumption of juvenile salmonids by Caspian terns nesting on Brooks Island in central San Francisco Bay during 2008 and 2009. Estimated salmonid consumption was similar to 205,000 smolts (95% confidence interval, 175,000-245,000 smolts) in 2008 and similar to 167,000 smolts (144,000-191,000 smolts) in 2009. The interannual difference in smolt consumption was due to the smaller size of the tern colony and lower nesting success in 2009. Estimated predation rates on ESA-listed Central Valley spring-run Chinook salmon Oncorhynchus tshawytscha (0.1%) were lower than those on unlisted fall-run Chinook salmon (1.0%). Continuation of the current downward trend in the number of Caspian terns nesting on Brooks Island and the resulting reductions in salmonid predation would not be sufficient to reverse salmonid declines in San Francisco Bay. The proposed enhancement of the Brooks Island Caspian tern colony to 3,000 individuals would at most cause declines in annual population growth rates of 0.28% for fall-run Chinook salmon and 0.02% for threatened spring-run Chinook salmon, assuming that the mortality from tern predation is 100% additive.Keywords: Patterns, Avian predation, Columbia River Estuary, Foraging ecology, Double crested cormorants, Bioenergetics model, Energy, Seabird populations, Waterbird predation, Passive integrated transponder
Biochemical adaptations of the retina and retinal pigment epithelium support a metabolic ecosystem in the vertebrate eye
Here we report multiple lines of evidence for a comprehensive model of energy metabolism in the vertebrate eye. Metabolic flux, locations of key enzymes, and our finding that glucose enters mouse and zebrafish retinas mostly through photoreceptors support a conceptually new model for retinal metabolism. In this model, glucose from the choroidal blood passes through the retinal pigment epithelium to the retina where photoreceptors convert it to lactate. Photoreceptors then export the lactate as fuel for the retinal pigment epithelium and for neighboring Mu ̈ ller glial cells. We used human retinal epithelial cells to show that lactate can suppress consumption of glucose by the retinal pigment epithelium. Suppression of glucose consumption in the retinal pigment epithelium can increase the amount of glucose that reaches the retina. This framework for understanding metabolic relationships in the vertebrate retina provides new insights into the underlying causes of retinal disease and age-related vision loss
Impact of Changes to the Atmospheric Soluble Iron Deposition Flux on Ocean Biogeochemical Cycles in the Anthropocene
Iron can be a growth‐limiting nutrient for phytoplankton, modifying rates of net primary production, nitrogen fixation, and carbon export ‐ highlighting the importance of new iron inputs from the atmosphere. The bioavailable iron fraction depends on the emission source and the dissolution during transport. The impacts of anthropogenic combustion and land use change on emissions from industrial, domestic, shipping, desert, and wildfire sources suggest that Northern Hemisphere soluble iron deposition has likely been enhanced between 2% and 68% over the Industrial Era. If policy and climate follow the intermediate Representative Concentration Pathway 4.5 trajectory, then results suggest that Southern Ocean (>30°S) soluble iron deposition would be enhanced between 63% and 95% by 2100. Marine net primary productivity and carbon export within the open ocean are most sensitive to changes in soluble iron deposition in the Southern Hemisphere; this is predominantly driven by fire rather than dust iron sources. Changes in iron deposition cause large perturbations to the marine nitrogen cycle, up to 70% increase in denitrification and 15% increase in nitrogen fixation, but only modestly impacts the carbon cycle and atmospheric CO2 concentrations (1–3 ppm). Regionally, primary productivity increases due to increased iron deposition are often compensated by offsetting decreases downstream corresponding to equivalent changes in the rate of phytoplankton macronutrient uptake, particularly in the equatorial Pacific. These effects are weaker in the Southern Ocean, suggesting that changes in iron deposition in this region dominates the global carbon cycle and climate response
CMIP5 Historical Simulations (1850-2012) with GISS ModelE2
Observations of climate change during the CMIP5 extended historical period (1850-2012) are compared to trends simulated by six versions of the NASA Goddard Institute for Space Studies ModelE2 Earth System Model. The six models are constructed from three versions of the ModelE2 atmospheric general circulation model, distinguished by their treatment of atmospheric composition and the aerosol indirect effect, combined with two ocean general circulation models, HYCOM and Russell. Forcings that perturb the model climate during the historical period are described. Five-member ensemble averages from each of the six versions of ModelE2 simulate trends of surface air temperature, atmospheric temperature, sea ice and ocean heat content that are in general agreement with observed trends, although simulated warming is slightly excessive within the past decade. Only simulations that include increasing concentrations of long-lived greenhouse gases match the warming observed during the twentieth century. Differences in twentieth-century warming among the six model versions can be attributed to differences in climate sensitivity, aerosol and ozone forcing, and heat uptake by the deep ocean. Coupled models with HYCOM export less heat to the deep ocean, associated with reduced surface warming in regions of deepwater formation, but greater warming elsewhere at high latitudes along with reduced sea ice. All ensembles show twentieth-century annular trends toward reduced surface pressure at southern high latitudes and a poleward shift of the midlatitude westerlies, consistent with observations
Ecology and genomics of an important crop wild relative as a prelude to agricultural innovation
Domesticated species are impacted in unintended ways during domestication and breeding. Changes in the nature and intensity of selection impart genetic drift, reduce diversity, and increase the frequency of deleterious alleles. Such outcomes constrain our ability to expand the cultivation of crops into environments that differ from those under which domestication occurred. We address this need in chickpea, an important pulse legume, by harnessing the diversity of wild crop relatives. We document an extreme domestication-related genetic bottleneck and decipher the genetic history of wild populations. We provide evidence of ancestral adaptations for seed coat color crypsis, estimate the impact of environment on genetic structure and trait values, and demonstrate variation between wild and cultivated accessions for agronomic properties. A resource of genotyped, association mapping progeny functionally links the wild and cultivated gene pools and is an essential resource chickpea for improvement, while our methods inform collection of other wild crop progenitor species
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Sustainable development goal 2: improved targets and indicators for agriculture and food security
The pursuit of global food security and agricultural sustainability, the dual aim of the
second Sustainable Development Goal (SDG-2), requires urgent and concerted action
from developing and developed countries. This, in turn, depends on clear and
universally applicable targets and indicators which are partially lacking. The novel and
complex nature of the SDGs poses further challenges to their implementation on the
ground, especially in the face of interlinkages across SDG objectives and scales. Here
we review the existing SDG-2 indicators, propose improvements to facilitate their
operationalization and illustrate their practical implementation in Nigeria, Brazil and the
Netherlands. This exercise provides insights into the concrete actions needed to
achieve SDG-2 across contrasting development contexts and highlights the challenges
of addressing the links between targets and indicators within and beyond SDG-2.
Ultimately, it underscores the need for integrated policies and reveals opportunities to
leverage the fulfillment of SDG-2 worldwide
HETDEX Public Source Catalog 1: 220K Sources Including Over 50K Lyman Alpha Emitters from an Untargeted Wide-area Spectroscopic Survey
We present the first publicly released catalog of sources obtained from the
Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). HETDEX is an integral
field spectroscopic survey designed to measure the Hubble expansion parameter
and angular diameter distance at 1.88<z<3.52 by using the spatial distribution
of more than a million Ly-alpha-emitting galaxies over a total target area of
540 deg^2. The catalog comes from contiguous fiber spectra coverage of 25 deg^2
of sky from January 2017 through June 2020, where object detection is performed
through two complementary detection methods: one designed to search for line
emission and the other a search for continuum emission. The HETDEX public
release catalog is dominated by emission-line galaxies and includes 51,863
Ly{\alpha}-emitting galaxy (LAE) identifications and 123,891 OII-emitting
galaxies at z<0.5. Also included in the catalog are 37,916 stars, 5274
low-redshift (z<0.5) galaxies without emission lines, and 4976 active galactic
nuclei. The catalog provides sky coordinates, redshifts, line identifications,
classification information, line fluxes, OII and Ly-alpha line luminosities
where applicable, and spectra for all identified sources processed by the
HETDEX detection pipeline. Extensive testing demonstrates that HETDEX redshifts
agree to within deltaz < 0.02, 96.1% of the time to those in external
spectroscopic catalogs. We measure the photometric counterpart fraction in deep
ancillary Hyper Suprime-Cam imaging and find that only 55.5% of the LAE sample
has an r-band continuum counterpart down to a limiting magnitude of r~26.2 mag
(AB) indicating that an LAE search of similar sensitivity with photometric
pre-selection would miss nearly half of the HETDEX LAE catalog sample. Data
access and details about the catalog can be found online at http://hetdex.org/.Comment: 38 pages, 20 figures. Data access and details about the catalog can
be found online at http://hetdex.org/. A copy of the catalogs presented in
this work (Version 3.2) is available to download at Zenodo
doi:10.5281/zenodo.744850
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