2,472 research outputs found
The ecology of seamounts: structure, function, and human impacts.
In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research
Solar cycle variation in solar f-mode frequencies and radius
Using data from the Global Oscillation Network Group (GONG) covering the
period from 1995 to 1998, we study the change with solar activity in solar
f-mode frequencies. The results are compared with similar changes detected from
the Michelson Doppler Imager (MDI) data. We find variations in f-mode
frequencies which are correlated with solar activity indices. If these changes
are due to variation in solar radius then the implications are that the solar
radius decreases by about 5 km from minimum to maximum activity.Comment: To appear in Solar Physic
Exceptional biodiversity of the cryptofaunal decapods in the Chagos Archipelago, central Indian Ocean
The Chagos Archipelago is geographically remote and isolated from most direct anthropogenic pressures. Here, we quantify the abundance and diversity of decapod crustaceans inhabiting dead coral colonies, representing a standardised microhabitat, across the Archipelago. Using morphological and molecular techniques we recorded 1868 decapods from 164 nominal species within 54 dead coral colonies, but total species estimates (Chao1 estimator) calculate at least 217 species. Galatheids were the most dominant taxa, though alpheids and hippolytids were also very abundant. 32% of species were rare, and 46% of species were found at only one atoll. This prevalence of rarer species has been reported in other cryptofauna studies, suggesting these assemblages maybe comprised of low-abundance species. This study provides the first estimate of diversity for reef cryptofauna in Chagos, which will serve as a useful baseline for global comparisons of coral reef biodiversity
Cold-water coral distributions in the Drake Passage area from towed camera observations – initial interpretations
This article is distributed under the terms of the Creative Commons Public Domain. The definitive version was published in PLoS One 6 (2011): e16153, doi:10.1371/journal.pone.0016153.Seamounts are unique deep-sea features that create habitats thought to have high levels of endemic fauna, productive fisheries and benthic communities vulnerable to anthropogenic impacts. Many seamounts are isolated features, occurring in the high seas, where access is limited and thus biological data scarce. There are numerous seamounts within the Drake Passage (Southern Ocean), yet high winds, frequent storms and strong currents make seafloor sampling particularly difficult. As a result, few attempts to collect biological data have been made, leading to a paucity of information on benthic habitats or fauna in this area, particularly those on primarily hard-bottom seamounts and ridges. During a research cruise in 2008 six locations were examined (two on the Antarctic margin, one on the Shackleton Fracture Zone, and three on seamounts within the Drake Passage), using a towed camera with onboard instruments to measure conductivity, temperature, depth and turbidity. Dominant fauna and bottom type were categorized from 200 randomized photos from each location. Cold-water corals were present in high numbers in habitats both on the Antarctic margin and on the current swept seamounts of the Drake Passage, though the diversity of orders varied. Though the Scleractinia (hard corals) were abundant on the sedimented margin, they were poorly represented in the primarily hard-bottom areas of the central Drake Passage. The two seamount sites and the Shackleton Fracture Zone showed high numbers of stylasterid (lace) and alcyonacean (soft) corals, as well as large numbers of sponges. Though data are preliminary, the geological and environmental variability (particularly in temperature) between sample sites may be influencing cold-water coral biogeography in this region. Each area observed also showed little similarity in faunal diversity with other sites examined for this study within all phyla counted. This manuscript highlights how little is understood of these isolated features, particularly in Polar regions.This work was funded by the National Science Foundation’s Antarctic Earth Sciences Program (ANT0636787 awarded to LFR and RGW) and a CenSeam
minigrant (awarded to RGW), and RGW is supported by a SOEST Young Investigator Fellowship from the University of Hawaii at Manoa
Genetic structure of the tall sea pen Funiculina quadrangularis in NW Scottish sea lochs
The tall sea pen Funiculina quadrangularis has a patchy distribution around the UK, being found in sheltered waters below 20 m depth on the northwest coast of Scotland and Ireland. The limited distribution and sensitivity to bottom fishing activities make F. quadrangularis vulnerable to reduction in population numbers that may lead to genetic isolation and reduced diversity. Because of this vulnerability and low resilience to physical disturbance, the tall sea pen is recognised as a Species of Principle Importance under the Natural Environment and Rural Communities Act, 2006, UK. (http://www.legislation.gov.uk/ukpga/2006/16/contents) and is also on the Biodiversity Action Plan list of Priority Species for the UK. In the Mediterranean it is recognised as a sensitive and essential fish habitat because it forms habitat for several commercially important crustaceans. The aim of this study was to understand the current state of the genetic structure and gene flow of F. quadrangularis in areas of NW Scotland. We developed 10 microsatellite markers and used them to genotype 176 samples from four populations. Overall, our results suggest that there is high genetic diversity and high gene flow between colonies of F. quadrangularis in and among locations in Loch Linnhe and Loch Duich. As a result of the high rates of gene flow, genetic differentiation between sites was low. This may provide resilience to human impacts if distant populations have a high connectivity. However, care must be taken, as small but significant isolation by distance was found between the most geographically distant sites and only a small part of the species range was examined in this study. The genetic tools developed here will provide a foundation for wider studies of this vulnerable species
Long term time variability of cosmic rays and possible relevance to the development of life on Earth
An analysis is made of the manner in which the cosmic ray intensity at Earth
has varied over its existence and its possible relevance to both the origin and
the evolution of life. Much of the analysis relates to the 'high energy' cosmic
rays () and their variability due to the changing
proximity of the solar system to supernova remnants which are generally
believed to be responsible for most cosmic rays up to PeV energies. It is
pointed out that, on a statistical basis, there will have been considerable
variations in the likely 100 My between the Earth's biosphere reaching
reasonable stability and the onset of very elementary life. Interestingly,
there is the increasingly strong possibility that PeV cosmic rays are
responsible for the initiation of terrestrial lightning strokes and the
possibility arises of considerable increases in the frequency of lightnings and
thereby the formation of some of the complex molecules which are the 'building
blocks of life'. Attention is also given to the well known generation of the
oxides of nitrogen by lightning strokes which are poisonous to animal life but
helpful to plant growth; here, too, the violent swings of cosmic ray
intensities may have had relevance to evolutionary changes. A particular
variant of the cosmic ray acceleration model, put forward by us, predicts an
increase in lightning rate in the past and this has been sought in Korean
historical records. Finally, the time dependence of the overall cosmic ray
intensity, which manifests itself mainly at sub-10 GeV energies, has been
examined. The relevance of cosmic rays to the 'global electrical circuit'
points to the importance of this concept.Comment: 18 pages, 5 figures, accepted by 'Surveys in Geophysics
Forty years of SNOMED: a literature review
BACKGROUND: Over a period of 40 years, SNOMED has developed from a pathology-specific nomenclature (SNOP) into a logic-based health care terminology. In spite of its long existence and continuous evolvement, it is yet unknown to what extent SNOMED is used in clinical practice, and what benefits were achieved. The aim of this paper is to investigate this by providing an overview of published studies in which a version of SNOMED was studied or applied. METHODS: This paper analyzes the use of SNOMED over time, as reflected in scientific publications, by means of Medline literature search in PubMed. The search included papers from 1966 until June 2006. For each selected paper the following characteristics were classified: version, medical domain, coding moment (during or after the care process), usage, and type of evaluation (e.g., does SNOMED work, does SNOMED help). RESULTS: 250 papers were included in this research. The number of annual publications has increased, as has the number of domains in which SNOMED is being used. Theoretical studies mainly concern comparison of SNOMED to other terminological systems and SNOMED as an illustration of a terminological systems' theory. Few studies are available on the usage of SNOMED in clinical practice, largely involving coding information and retrieval/aggregation based on SNOMED codes. CONCLUSION: The clinical application of SNOMED is broadening beyond pathology. The majority of studies concern proving the value of SNOMED in theory. Fewer studies are available on the usage of SNOMED in clinical practice. Literature gives no indication of the use of SNOMED for direct care purposes such as decision suppor
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