19°0'0"E 18°E 17°E 16°E 15°E 14°E 13°E 45°N 44°N 43°N 42°N 41°N 40°N 0 100 200 50 km A B -200 -1200 -500 (m) A B Slope section ADW NAdDW LIW -0 A NAdDW production area NAdDW LIW ADW Ionian Sea Tyrrhenian Sea Italy Adriatic Sea Hotspot Ecosystem Research and Man's Impact On European Seas Annual meeting 2011 Malaga, 11-15 April 2011 CONSIGLIO NAZIONALE DELLE RICERCHE Istituto di Scienze Marine Submarine slides Canyons Gondola deformation belt Seamount Mooring stations 0 10 20 30 40 5 Km - 35 m -1205 water depth A 0 10 20 30 40 5 Km Giant grooves Barchan crest Furrows Mud waves ridge Scour Mud waves area Furrows area Giant sediment drift area Moat area Comet mark area Complex area N 3 km 50 m 1200 m AR89 D AR89 0 45 90 135 180 225 270 315 0 4 8 12 (cm/sec) 0 45 90 135 180 225 270 315 0 5 10 15 20 25 (cm/sec) 2 4 3 5 6 1 2 3 4 5 6 1 12 Km N 6 km N SE120 SE151 SE151 600 575 625 550 msec 1200 m -850 -900 -950 -1000 m 1 km The reshaping of the South West Adriatic Margin by pervasive dense shelf water cascading Foglini F., Trincardi F., Campiani E. & Langone L. Istituto di Scienze Marine ISMAR – CNR, Bologna, Italy Simplified intermediate- and deep-water circulation in the Adriatic Sea: NAdDW=North Adriatic Dense Water; LIW=Levantine Intermediate Water; ADW=Adriatic Dense Water. Cascading NAdDW impact the seafloor of the SW Adriatic margin, eroding and depositing large amounts of fine-grained sediment below a markedly erosional upper slope. By cascading across the slope over a prolonged interval (several weeks each year), the dense NAdDW impinges the seafloor and interacts with the margin morphology, generating: patchy fields of large-scale mud waves; a variety of erosional bed forms, such as moats, furrows and comet marks; an area of widespread sea floor erosion. The Southwest Adriatic Margin includes a steep and morphologically complex continental slope stretching about 400 km from the Pelagosa sill to the Otranto strait. The area has been investigated through multibeam surveys accompanied by high-resolution seismic stratigraphic surveys investigating glacial and post-glacial deposits. The margin is dissected by submarine slides, with head scars up to 10 km along the shelf edge and run-out distances of tens of km, an active fault system (the Gondola deformation belt), Bari Canyon and a set of shallowly incised and relatively straight canyons located further south. After the end of the last glacial sea level low stand the North Adriatic shallow shelf became progressively drowned as a consequence of the eustatic rise. Through its progressive drowning, this region became a shallow shelf and one of the Mediterranean key sites for the formation of dense shelf waters through wind-forced winter cooling. The dense waters formed through this process move to the south, along the western side of the Adriatic, and reach the South Adriatic slope across which they cascade hugging the sea floor and generating a myriad of depositional and erosional effects such as: giant sediment drifts down to 1200m water depth, muddy and sandy sediment waves, comet marks against pre-existing slide blocks, furrow fields, large scours at the shelf edge and large erosional moats against major morphological barriers. CONCLUSION -The cascadings of dense shelf watersconcur to a thorough “restyling” of the margin morphology interacting with the pre-existing and markedly differentiated morphologies and sediment distribution. -Mapping the active bedforms and the areas of dominant seafloor erosion allows quantification of the extent to which bottom-hugging currents are effective in reshaping the margin morphology. -The seasonal impact of cascadings water has also a major effect on benthic fauna distribution. Furrow fields at the base of the southern slope with an area of 71.69km2 in water depth between 753 and 960m. The field emanates from the mouth of a slope gulley oriented roughly N-S and appear to expand and diverge eastward. The typical depth of the furrow is 0.5m and