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TitleGeomorphic features and benthos in a deep glacial trough in Atlantic Canada
 
AuthorLacharité, M; Brown, C J; Normandeau, AORCID logo; Todd, B JORCID logo
SourceAnnual Conference, GEOHAB 2019, Marine Geological and Biological Habitat Mapping, abstracts; 2019 p. 115
Image
Year2019
Alt SeriesNatural Resources Canada, Contribution Series 20190076
MeetingAnnual Conference, GEOHAB 2019, Marine Geological and Biological Habitat Mapping; Saint Petersburg; RU; May 13-17, 2019
Documentbook
Lang.English
Mediadigital
File formatpdf
ProvinceEastern offshore region; Newfoundland and Labrador; Nova Scotia
NTS11C; 11D; 11E; 11F; 11K; 11L; 11M; 11N
AreaLaurentian Channel
Lat/Long WENS -60.0000 -56.0000 48.0000 44.0000
Subjectsmarine geology; surficial geology/geomorphology; environmental geology; geophysics; Nature and Environment; Science and Technology; submarine features; submarine troughs; continental margins; continental shelf; glacial history; glaciation; ice flow; glacial deposits; tills; moraines; glacial features; icebergs; glacial scours; pockmarks; pits; ecology; benthos; mapping techniques; seafloor topography; geophysical surveys; acoustic surveys, marine; Laurentide Ice Sheet; Laurentian Moraine; sea pens; Pennatula sp.; Anthoptilum grandiflorum; Laurentian Channel Area of Interest; Habitats; monitoring
Illustrationslocation maps; geoscientific sketch maps; photographs; geophysical profiles; geophysical images; plots
ProgramOffshore Geoscience
Released2019 01 01
AbstractThe Laurentian Channel is a deep glacial trough located in Atlantic Canada, extending >1500 km from the St. Lawrence Estuary to the shelf edge between Nova Scotia and Newfoundland. The channel acted as a major conduit of ice-stream flow underlying the Laurentide Ice Sheet during the last glaciation event in North America. The impact of glaciation on the seabed is suggested by the presence of iceberg scours and circular depressions (pockmarks and iceberg pits) attributed to disturbance caused by grounded moving icebergs. The outer Laurentian Channel close to its entrance at the shelf edge has been designated as an Area of Interest (AOI) for the establishment of a Marine Protected Area under Canada's Oceans Act. However, baseline information on the composition and distribution of benthic biota in relation to seabed features was lacking. Here, a benthoscape map of the outer Laurentian Channel along its eastern escarpment (51-497 m depth) was generated using geomorphic features mapped with multibeam sonar (density of iceberg scours and pockmarks/iceberg pits, depth and slope) and ground-truthed with surficial geology samples and underwater imagery. Individual surrogates and mapped patterns were compared to faunal patterns (infauna and epifauna) derived from the ground-truthing. Maximal infauna richness and abundance occurred along the escarpment of the Channel, generally decreasing with increasing depth. Both depth and density of pockmarks/iceberg pits influenced community composition. Some benthoscape classes had close associations with distinct infauna, but diff use patterns were mostly observed. Epifauna - namely sea pens - were most abundant at the confluence of multiple benthoscape classes. This study provided a contextual overview of the composition of the benthoscape and associated fauna in the Laurentian Channel AOI, which is necessary to establish a sound monitoring program in this potential marine closure.
Summary(Plain Language Summary, not published)
The Laurentian Channel is a deep glacial trough located in Atlantic Canada, extending >1500 km from the St. Lawrence Estuary to the shelf edge between Nova Scotia and Newfoundland. The outer Laurentian Channel close to its entrance at the shelf edge has been designated as an Area of Interest (AOI) for the establishment of a Marine Protected Area under Canada¿s Oceans Act. A seabed map of the outer Laurentian Channel was generated. Individual surrogates and mapped patterns were compared to faunal patterns (infauna and epifauna) derived from the ground-truthing. This study provided a contextual overview of the composition of the seabed and associated fauna in the Laurentian Channel AOI, which is necessary to establish a sound monitoring program in this potential marine closure.
GEOSCAN ID314710

 
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