Dredged gravel beds (circalittoral)
Biotope description :
Typically with a reduced faunal abundance and diversity compared to surrounding undredged gravel areas. The infaunal community is more typical of a sandy gravel/gravely sand than of a gravel substrate. The following characterised dredged areas of the Hastings shingle bank (SE England): Balanus crenatus, Lagis koreni, Spiophanes bombyx, Urothoe elegans, Ampelisca spinipes, Lanice conchilega, Cerianthus lloydii (compare with species listed under the record for ‘undredged gravel’). Few sessile and attached epifauna in comparison to undredged gravel.
Biotope description :
Typically with a reduced faunal abundance and diversity compared to surrounding undredged gravel areas. The infaunal community is more typical of a sandy gravel/gravely sand than of a gravel substrate. The following characterised dredged areas of the Hastings shingle bank (SE England): Balanus crenatus, Lagis koreni, Spiophanes bombyx, Urothoe elegans, Ampelisca spinipes, Lanice conchilega, Cerianthus lloydii (compare with species listed under the record for ‘undredged gravel’). Few sessile and attached epifauna in comparison to undredged gravel.
Key-words :
gravel, dredging, dredged, aggregate
Habitat description :
Gravel sediments, exposed at the seabed surface, worked for aggregate extraction, usually laying within an area of extensive gravel deposit. Typically has a reduced gravel content (so elevated sand content) resulting from selective removal of gravel particles.
Habitat description :
Gravel sediments, exposed at the seabed surface, worked for aggregate extraction, usually laying within an area of extensive gravel deposit. Typically has a reduced gravel content (so elevated sand content) resulting from selective removal of gravel particles.
Place : Baie de Saint-Brieuc (Côtes d'Armor, France)
Mesh regional Sea : Western Channel
Comments : AREVAL 2005 Cruise (Ifremer/DEL)
Mesh regional Sea : Western Channel
Comments : AREVAL 2005 Cruise (Ifremer/DEL)
Lat :
48.620050
48.620050
Lon :
-2.543483
-2.543483
Description :
Numerous furrows due to the suction tool of suction dredgers
Comments :
Overall, this acoustic imagery shows a sector with medium sands (s-m) intensely colonized by a dense Crepidula fornicata biocenosis around a rocky sunken reef (r). Recently, industrial use was made of this area to collect slipper limpets for soil enrichment. The bottoms impacted by numerous furrows due to the suction tool of suction dredgers show a maze of sub-parallel indentations which affect the underlying soft sedimentary cover. Four cages (c) used for scientific rearing of Pecten maximus, are seen at the top left of the sonogram.
Technique(s) :
Backscatter images
- Type
sidescan
- Make & Model
Edgetech – DF1000
- Operating frequency (kHz)
105
- Total swathe width (m)
100
- Approximate water depth (m)
12
- Gray level (positive or negative image)
negative image
Numerous furrows due to the suction tool of suction dredgers
Comments :
Overall, this acoustic imagery shows a sector with medium sands (s-m) intensely colonized by a dense Crepidula fornicata biocenosis around a rocky sunken reef (r). Recently, industrial use was made of this area to collect slipper limpets for soil enrichment. The bottoms impacted by numerous furrows due to the suction tool of suction dredgers show a maze of sub-parallel indentations which affect the underlying soft sedimentary cover. Four cages (c) used for scientific rearing of Pecten maximus, are seen at the top left of the sonogram.
Technique(s) :
Backscatter images
- Type
sidescan
- Make & Model
Edgetech – DF1000
- Operating frequency (kHz)
105
- Total swathe width (m)
100
- Approximate water depth (m)
12
- Gray level (positive or negative image)
negative image
Date : 14/05/2005
Date accuracy : Day
From : Houlgatte, 2006 ; Blanchard et Hamon, 2006
Contact email : Axel.Ehrhold@ifremer.fr
Data owner : Ifremer
Date accuracy : Day
From : Houlgatte, 2006 ; Blanchard et Hamon, 2006
Contact email : Axel.Ehrhold@ifremer.fr
Data owner : Ifremer
Habitats signatures website copyright MESH 2005-2006. All content copyright respective owners.