407 research outputs found
Landscape mapping at sub-Antarctic South Georgia provides a protocol for underpinning large-scale marine protected areas
Global biodiversity is in decline, with the marine environment experiencing significant and increasing anthropogenic pressures. In response marine protected areas (MPAs) have increasingly been adopted as the flagship approach to marine conservation, many covering enormous areas. At present, however, the lack of biological sampling makes prioritising which regions of the ocean to protect, especially over large spatial scales, particularly problematic. Here we present an interdisciplinary approach to marine landscape mapping at the sub-Antarctic island of South Georgia as an effective protocol for underpinning large-scale (105â106 âkm2) MPA designations. We have developed a new high-resolution (100âm) digital elevation model (DEM) of the region and integrated this DEM with bathymetry-derived parameters, modelled oceanographic data, and satellite primary productivity data. These interdisciplinary datasets were used to apply an objective statistical approach to hierarchically partition and map the benthic environment into physical habitats types. We assess the potential application of physical habitat classifications as proxies for biological structuring and the application of the landscape mapping for informing on marine spatial plannin
On the ecological relevance of landscape mapping and its application in the spatial planning of very large marine protected areas
In recent years very large marine protected areas (VLMPAs) have become the dominant form of spatial protection in the marine environment. Whilst seen as a holistic and geopolitically achievable approach to conservation, there is currently a mismatch between the size of VLMPAs, and the data available to underpin their establishment and inform on their management. Habitat mapping has increasingly been adopted as a means of addressing paucity in biological data, through use of environmental proxies to estimate species and community distribution. Small-scale studies have demonstrated environmental-biological links in marine systems. Such links, however, are rarely demonstrated across larger spatial scales in the benthic environment. As such, the utility of habitat mapping as an effective approach to the ecosystem-based management of VLMPAs remains, thus far, largely undetermined.
The aim of this study was to assess the ecological relevance of broadscale landscape mapping. Specifically we test the relationship between broad-scale marine landscapes and the structure of their benthic faunal communities. We focussed our work at the sub-Antarctic island of South Georgia, site of one of the largest MPAs in the world. We demonstrate a statistically significant relationship between environmentally derived landscape mapping clusters, and the composition of presence-only species data from the region. To demonstrate this relationship required specific re-sampling of historical species occurrence data to balance biological rarity, biological cosmopolitism, range-restricted sampling and fine-scale heterogeneity between sampling stations. The relationship reveals a distinct biological signature in the faunal composition of individual landscapes, attributing ecological relevance to South Georgia's environmentally derived marine landscape map. We argue therefore, that landscape mapping represents an effective framework for ensuring representative protection of habitats in management plans. Such scientific underpinning of marine spatial planning is critical in balancing the needs of multiple stakeholders whilst maximising conservation payoff
The velocity distribution of nearby stars from Hipparcos data I. The significance of the moving groups
We present a three-dimensional reconstruction of the velocity distribution of
nearby stars (<~ 100 pc) using a maximum likelihood density estimation
technique applied to the two-dimensional tangential velocities of stars. The
underlying distribution is modeled as a mixture of Gaussian components. The
algorithm reconstructs the error-deconvolved distribution function, even when
the individual stars have unique error and missing-data properties. We apply
this technique to the tangential velocity measurements from a kinematically
unbiased sample of 11,865 main sequence stars observed by the Hipparcos
satellite. We explore various methods for validating the complexity of the
resulting velocity distribution function, including criteria based on Bayesian
model selection and how accurately our reconstruction predicts the radial
velocities of a sample of stars from the Geneva-Copenhagen survey (GCS). Using
this very conservative external validation test based on the GCS, we find that
there is little evidence for structure in the distribution function beyond the
moving groups established prior to the Hipparcos mission. This is in sharp
contrast with internal tests performed here and in previous analyses, which
point consistently to maximal structure in the velocity distribution. We
quantify the information content of the radial velocity measurements and find
that the mean amount of new information gained from a radial velocity
measurement of a single star is significant. This argues for complementary
radial velocity surveys to upcoming astrometric surveys
A peptide trivalent arsenical inhibits tumor angiogenesis by perturbing mitochondrial function in angiogenic endothelial cells
AbstractMitochondria are the powerhouse of the cell and their disruption leads to cell death. We have used a peptide trivalent arsenical, 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO), to inactivate the adenine nucleotide translocator (ANT) that exchanges matrix ATP for cytosolic ADP across the inner mitochondrial membrane and is the key component of the mitochondrial permeability transition pore (MPTP). GSAO triggered Ca2+-dependent MPTP opening by crosslinking Cys160 and Cys257 of ANT. GSAO treatment caused a concentration-dependent increase in superoxide levels, ATP depletion, mitochondrial depolarization, and apoptosis in proliferating, but not growth-quiescent, endothelial cells. Endothelial cell proliferation drives new blood vessel formation, or angiogenesis. GSAO inhibited angiogenesis in the chick chorioallantoic membrane and in solid tumors in mice. Consequently, GSAO inhibited tumor growth in mice with no apparent toxicity at efficacious doses
Distribution of Vulnerable Marine Ecosystems at the South Sandwich Islands: Results From the Blue Belt Discovery Expedition 99 Deep-Water Camera Surveys
The South Sandwich Islands (SSI) are a chain of volcanic islands located to the east of the Scotia Sea, approximately 700 km south-east of South Georgia. To date, knowledge of the SSI benthic environment remains limited. In this context, the Blue Belt Programme conducted a scientific survey in the SSI Marine Protected Area (MPA) during February/March 2019 to examine the biodiversity and distribution of benthic communities and their potential vulnerability to licensed longline research fisheries. Here we report results from analysis of multibeam echosounder (MBES) data and drop camera imagery data collected in selected locations around the SSI. A total of eight vulnerable marine ecosystem (VME) indicator morphotaxa were mapped along the slopes of the SSI, showing a substantial variation in taxon composition and frequency of occurrence, both along bathymetric and latitudinal gradients. Our results suggest that VME indicator taxa are mostly restricted to waters shallower than 700 m. As such, based on our present understanding of the regionâs benthic environment the MPA, as currently established, offers effective protection for the majority of the VME indicator taxa
Using longitudinal survival probabilities to test field vigour estimates in sugar maple (Acer saccharum Marsh.)
Tree mortality is a major force driving forest dynamics. To foresters, however, tree mortality is often considered a loss in productivity. To reduce tree mortality, silvicultural systems, such as selection cuts, aim at removing trees that are more likely to die. In order to identify trees with higher risks of mortality, field classifications are employed that assess vigour based on external characteristics of trees. We used a novel longitudinal approach for estimating survival probabilities based on ring-width measurements, initially developed by Bigler and Bugmann [Bigler, C., Bugmann, H., 2004. Predicting the time of tree death using dendrochronological data. Ecol. Appl. 14 (3), 902-914], to parameterize a survival probability model for sugar maple (Acer saccharum Marsh.) and to test whether field-assessed tree vigour classes are corroborated by survival probabilities determined from radial growth history. Data from 56 dead and 321 live sugar maples were collected in stands in western Quebec (Canada) that had undergone a selection cut â10 years prior to sampling. Our results showed that tree vigour established from external defects and pathological symptoms, using the classification of Boulet [Boulet, B., 2005. D
ImpZ: a new photometric redshift code for galaxies and quasars
We present a combined galaxy-quasar approach to template-fitting photometric
redshift techniques and show the method to be a powerful one. The code (ImpZ)
is presented, developed and applied to two spectroscopic redshift catalogues,
namely the Isaac Newton Telescope Wide Angle Survey ELAIS N1 and N2 fields and
the Chandra Deep Field North. In particular, optical size information is used
to improve the redshift determination. The success of the code is shown to be
very good with Delta z/(1+z) constrained to within 0.1 for 92 per cent of the
galaxies in our sample. The extension of template-fitting to quasars is found
to be reasonable with Delta z/(1+z) constrained to within 0.25 for 68 per cent
of the quasars in our sample. Various template extensions into the far-UV are
also tested.Comment: 21 pages. MNRAS in press. Minor alterations to match MNRAS final
proo
Optical and Infrared Diagnostics of SDSS galaxies in the SWIRE Survey
We present the rest-frame optical and infrared colours of a complete sample
of 1114 z<0.3 galaxies from the Spitzer Wide-area InfraRed Extragalactic Legacy
Survey (SWIRE) and the Sloan Digital Sky Survey (SDSS). We discuss the optical
and infrared colours of our sample and analyse in detail the contribution of
dusty star-forming galaxies and AGN to optically selected red sequence
galaxies.
We propose that the optical (g-r) colour and infrared log(L_{24}/L_{3.6})
colour of galaxies in our sample are determined primarily by a bulge-to-disk
ratio. The (g-r) colour is found to be sensitive to the bulge-to-disk ratio for
disk-dominated galaxies, whereas the log(L_{24}/L_{3.6}) colour is more
sensitive for bulge-dominated systems.
We identify ~18% (195 sources) of our sample as having red optical colours
and infrared excess. Typically, the infrared luminosities of these galaxies are
found to be at the high end of star-forming galaxies with blue optical colours.
Using emission line diagnostic diagrams, 78 are found to have an AGN
contribution, and 117 are identified as star-forming systems. The red (g-r)
colour of the star-forming galaxies could be explained by extinction. However,
their high optical luminosities cannot. We conclude that they have a
significant bulge component.
The number densities of optically red star-forming galaxies are found to
correspond to ~13% of the total number density of our sample. In addition,
these systems contribute ~13% of the total optical luminosity density, and 28%
of the total infrared luminosity density of our SWIRE/SDSS sample. These
objects may reduce the need for "dry-mergers".Comment: 14 pages, 8 figures, 4 tables. Accepted for publication in MNRA
Dependence of Star Formation Activity On Stellar Mass and Environment From the Redshift One LDSS-3 Emission Line Survey (ROLES)
Using the sample from the \it Redshift One LDSS3 Emission line Survey \rm
(ROLES), we probe the dependence of star formation rate (SFR) and specific star
formation rate (sSFR) as a function of stellar mass and environment as
defined by local galaxy density, in the CDFS field. Our spectroscopic sample
consists of 312 galaxies with , corresponding to stellar mass
\log(M_*/M_{\sun})>8.5, and with [OII] derived star-formation rates
SFR>0.3M_{\sun}/yr, at . The results have been
compared directly with the Sloan Digital Sky Survey Stripe 82 sample at
. For star-forming galaxies, we confirm that there is
little correlation between SFR and density at . However, for the
lowest mass galaxies in our sample, those with
\log(M_*/M_{\sun})<10, we find that both the median SFR and specific SFR {\it
increase} significantly with increasing local density. The "downsizing" trend
for low mass galaxies to be quenched progressively later in time appears to be
more pronounced in moderately overdense environments. Overall we find that the
evolution of star-formation in galaxies is most strongly driven by their
stellar mass, with local galaxy density playing a role that becomes
increasingly important for lower mass galaxies.Comment: MNRAS accepte
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