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| Titel |
The use of photo-mosaics, bathymetry and sensor data into geographic information system for site description and faunal distribution analysis at the Menez Gwen Hydrothermal vent field |
| VerfasserIn |
Y. Marcon, H. Sahling, G. Bohrmann |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061475
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| Zusammenfassung |
| The Menez Gwen hydrothermal vent is located on the Mid-Atlantic Ridge at a depth of about
800m. Although it has been the focus of several expeditions and studies, the sites of active
venting at Menez Gwen are still under described, and it is not possible to get a global picture
of the sites from the published data. Exploration of deep-sea environments is commonly
performed using remotely operated vehicles (ROV) equipped with sensors, cameras and
powerful lights. But strong attenuation of light in the deep-sea constrains visual surveys to be
carried out from a few meters only above the seafloor, thus limiting the extent of the field of
view. Moreover, ROV-mounted positioning systems usually lack accuracy and cannot
be relied on for accurate relative positioning of sensor measurements, samplings,
and features of interest. Such limitations are hindrances for many applications. In
particular, site description or mapping of deep-sea benthic fauna over an area of
study usually requires lengthy surveys, and reliability of navigation data becomes a
major issue. Also, studying small-scale spatial variations of a physicochemical
parameter needs positions of sensor measurements or samplings to be known precisely.
To overcome this problem, maps of the seafloor can be generated in the form of
geo-referenced video- or photo-mosaics. Mosaics are constructed by assembling overlapping
images together into a larger image of the scene. To reduce the effects of drift in
the navigation data, the construction of the mosaics uses robust feature detection
and mapping capabilities to precisely relate consecutive images together. After
geo-referencing in a Geographic Information System (GIS), points of measurements
and sampling can be accurately pinpointed onto the mosaics to allow for spatial
analyses.
During cruise M82/3 to the Menez Gwen hydrothermal vent system, high-resolution
photo-mosaics of several sites of hydrothermal activity were constructed and geo-referenced
into GIS systems. The mosaics, together with high-resolution ship-borne bathymetry, allowed
unravelling the layout and morphology of the system at different scales. Through
GIS analyses, the distribution of the faunal communities in relation to the fluid
emission points was mapped and sensor data were integrated to allow describing the
spatial variation of water temperature based on CTD measurements. Results include
calculation of mussel beds surfaces and inferred estimates of biomass of Bathymodiolus
azoricus.
Acknowledgements: This work is supported by the European Commission under the EU
Framework 7 funded Marie Curie Initial Training Network (ITN) SENSEnet (contract
nº237868), and funded through DFG Research Center / Excellence Cluster "The Ocean in the
Earth System". |
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