dense shelf water cascading in the northwestern mediterranean during the cold winter 2005 quantification of the export through the gulf of lion and the catalan margin dense shelf water cascading in the northwestern mediterranean sea during winter 2005 which was shown to cause large erosion in the canyons and to influence deep benthic ecosystem was investigated using numerical modeling validated with temperature and current observations intense dense water formation took place on the gulf of lion and catalan shelves dense shelf water was transferred to the deep basin through three pathways the cap de creus canyon in the western gulf of lion already identified as a huge pathway was shown to export about 1000 km3 of dense water during two months the palamos and blanes canyons located on the catalan margin were shown to be important pathways for water formed locally and for water transiting from the gulf of lion after the cascading period dense shelf water was transported mostly toward the balearic sea

unexpected characteristics of the 150 km echoes observed over gadanki and their implications recent discovery of two distinct types of 150 km echoes namely type a and type b and subsequent progress in the large scale kinetic simulation of photoelectron induced plasma waves have begun a new era in resolving the five decades long 150 km echoing riddle in this paper we present hitherto unrevealed three important and unexpected findings on the two distinct types of 150 km echoes based on gadanki radar observations our observations show unexpected predominance of type a echoes strong seasonal dependence of both type a and type b echoes and a surprising connection of the type b echoes to the unusually deep solar minimum of 2008 2009 we discuss how these results provide important new clues in tethering the competing processes involved in the daytime 150 km echoes and have significance in the recently proposed photoelectron induced plasma fluctuations as a potential mechanism for the 150 km echoes

particle transport in the bari canyon southern adriatic sea to define the sediment transport pathways along the southern adriatic shelf and slope two oceanographic cruises were carried out in the southern adriatic in july 2004 and in march april 2005 to study the role of the bari canyon system on sediment dispersal three moorings including sediment traps and current meters have been deployed near the bottom at depths of 600 m for one year march 2004 march 2005 two moorings were deployed within the canyon station b in the northern branch and station c in the southern branch and one on the adjacent open slope north of the canyon system station a total mass fluxes tmfs measured by sediment traps were always higher in the canyon than on the adjacent slope the highest values were measured at station c average 8 07 g m 2 d 1 roughly double those of station b 3 07 g m 2 d 1 and the lowest outside the canyon at station a 1 69 g m 2 d 1 the highest tmf were recorded in spring 2004 a period characterized by the lowest water temperatures and the highest current speeds up to 72 cm 1 which were associated with the highest across slope current component along the canyon axes the simultaneous variations of fluxes occurring at the three stations imply that similar processes are active along the entire southern adriatic margin and that they are amplified inside the canyon in spring a vein of southward flowing north adriatic dense water naddw was observed along the adriatic shelf this was related to an enhanced across slope current component which was responsible for the higher particle fluxes both on the open slope and at the canyon stations these data suggest that the bari canyon is an efficient conduit for sediment from the adriatic continental shelf to the deep basin downcore profiles of 210 pb in sediments collected below the traps have been used to estimate sediment mass accumulation rates mars on a century scale on the open slope the annual trap flux recorded in 2004 2005 was lower than mar on the contrary in the bari canyon the annual trap flux was higher than mar indicating that the lateral advection of particles becomes predominant and that a fraction of the particles intercepted by sediment traps was only in transit through the canyon 2007 elsevier b v all rights reserved

descending ion layer property in the gadanki radar observations of 150 km echoes and its implication to the echoing phenomenon 1 gadanki radar observations of the daytime 150 km echoes displaying descending features resembling the descending ion layer behavior are presented the descending pattern is intriguing since it indicates the possible role of density gradient associated with the ion layer in generating the irregularities responsible for 150 km radar echoes not envisioned before unusually strong snr and narrow spectral features of these echoes clearly indicate the role of sharp density gradients in the echoing process given the fact that gadanki is located at magnetically low latitude it is argued that these descending echoing layers are produced by interchange instability on the gradient of daytime descending ion layer formed by meridional wind shear associated with tidal gravity waves quite similar to that observed during nighttime the observations reported here are first of its kind illustrating the role of density gradient layers and are important in furthering our understanding on the puzzling 150 km echoing phenomenon

reprint of on and off the beaten track megafaunal sessile life and adriatic cascading processes abstract valuable megafaunal sessile assemblages in the southern adriatic basin present a western eastern asymmetric distribution this is particularly evident when considering cold water coral cwc communities with most diverse and abundant live corals to be found along the western side on the contrary only spotty occurrences are documented in the eastern side and at times only in a sub fossil state we hypothesize that this asymmetry might derive from differential exposure of the adriatic floor to polarized hydrological processes in such a perspective vigorous albeit a periodical flushing of deep sea bottoms at times of cascading processes could be beneficial to sessile deep sea benthic communities by reinforcing the north adriatic dense water naddw contrasting excess silting and by enhancing the trophic web although no experimental evidence has been yet produced to test this hypothesis it gains some support by the observation that cwc are flourishing in the general area of the bari canyon and adjacent bottoms flushed by dense shelf water dsw cascading while they are much less developed on the basin s opposite side unaffected by this phenomenon

high resolution observations of 150 km echoes at jicamarca high resolution soundings of equatorial upper e region echoes at jicamarca exhibit gravity wave modulated signal intensity distributions and doppler velocities corresponding to vertical plasma drifts a gravity wave wind driven interchange instability is suggested as a possible generation mechanism of the field aligned plasma irregularities responsible for the echoes the echoes may be utilized in gravity wave studies and in zonal electric field measurements by radars with modest sensitivities

dense water bottom currents in the southern adriatic sea in spring 2012 abstract in february 2012 a severe cold spell in the european region triggered a massive production of very dense water on the northern mediterranean sea shelves the spreading phase of the newly formed dense water was extensively studied in the adriatic sea by means of 2 ship surveys and 5 moorings fully equipped to monitor the flow of the bottom layer for the adriatic sea opposite to the gulf of lions the area of cascading is far from the source area and this implies substantial modifications adjustments and dilution of the source water mass along its path with a spreading phase lasting several months indeed all the moorings detected events although weaker than in the preceding months until june 2012 the surveys detected 2 branches of naddw on the shelf the first branch not denser than 29 7 kg m3 and the second branch not denser than 29 5 kg m3 despite the extremely dense water generated in the northern adriatic during events of dense water flow moorings recorded temperatures generally between 12 5 and 13 c seldom less temperatures along the shelf break also did not fall below 13 c at depths greater than 400 m turbulent mixing therefore heavily modified the cascading plumes which left the shelf with thicknesses between 10 and 30 m mooring data in the lowermost 100 mab suggest that the thickness of the cascading layer increased by several tens of meters downslope as a consequence of entrainment detraining frictional layers as well as locations of active cascading were identified mostly by isolated casts highlighting the submesoscale domain of the downsloping plumes the use of ladcp data allowed identification of very energetic bottom flow 40 50 cm s in many locations with otherwise little signature in tracers not previously observed the bari canyon system bcs was so far recognized as a hot spot for cascading in the southern adriatic however during the 2012 event this is not the only preferred site for cascading significant dense flow was detected in other locations the northernmost mooring site closer to the inception of the cascading process in particular showed active cascading and several dynamical differences from the bcs denser water with thinner boundary layer events organized in multiple pulses with sub inertial periodicity and with very short duration 12 h to 1 day that is generally not seen in other locations

benthic habitat characterization and distribution from two representative sites of the deep water sml coral province mediterranean abstract two sites ms04 and ms06 from the santa maria di leuca sml coral province were analyzed by a video and acoustic survey during the national italian project apulian plateau bank ecosystem study aplabes site ms04 atlantis mound is characterized by a sub conical mound 500 m wide and 25 m high located at a water depth of about 650 m site ms06 yellow chain comprises several elongated reliefs nnw sse oriented up to 25 m high and 500 m in maximum lateral extent located at a depth of between 490 and 540 m at both sites two main mesohabitats mound and intermound containing several coral bearing and barren macrohabitats were observed in recorded videos and detected in side scan sonographs the coral rich macrohabitats characterized by densely packed colonies of the scleractinians madrepora oculata and secondarily lophelia pertusa m l are typically restricted to the mound areas the mud dominated ones almost devoid of m l colonies are more common within the intermound mesohabitat however on the most extensive mounds both macrohabitat typologies exist they are heterogeneously distributed on the mound surface often showing a clear differentiation along two opposite flanks of the same topographic feature m l rich macrohabitats are preferentially located on top and along the mound northeastern flank showing a typical step like distribution probably reflecting the arrangement of hard substrate outcrops along this flank fan shaped madrepora colonies and sponges are often oriented nnw sse implying together with other evidence a primary southwestern current flow the hard bottom macrohabitats of the southwestern mound flank are generally restricted to sparse exposed subvertical to overhanging scarps as well as to heterometric boulders located at the scarp base their fauna is mainly characterized by small sized organisms such as sponges and solitary scleractinians although m sized boulders may locally host very large antipatharian colonies leiopathes glaberrima the heterogeneous distribution of the observed benthic macrohabitats seems to be strictly related to the local topography the main current flow and consequently larvae food supply per unit of time and the substrate typology hard vs soft bottom

on a summer maximum in the occurrence frequency of 150 km f1 radar echoes over pohnpei 1 using three and a half years of 50 mhz radar data collected from pohnpei federated states of micronesia 6 96 n 158 19 e geographic 0 3 magnetic dip latitude we show for the first time that the occurrence frequency of 150 km or f1 echoes has a broad but conspicuous maximum during northern summer in this longitude sector with minimal activity in other months given a seasonal similarity to sporadic e es we suggest that an es layer instability cosgrove and tsunoda 2002 generates a polarization electric field which maps along geomagnetic field lines to the f1 region there forms thin plasma sheets that provide gradients to excite 3 m scale plasma waves via an interchange process

proliferation and demise of deep sea corals in the mediterranean during the younger dryas abstract uranium series and radiocarbon ages are reported for deep sea corals madrepora oculata desmophyllum dianthus lophelia pertusa and caryophyllia smithii from the mediterranean sea u series dating indicates that deep sea corals have persisted in the mediterranean for over 480 000 years especially during cool interstadial periods the most prolific period of growth however appears to have occurred within the younger dryas yd period from 12 900 to 11 700 years bp followed by a short 330 years phase of post yd coral growth from 11 230 to 10 900 years bp this indicates that deep sea corals were prolific in the mediterranean not only during the return to the more glacial like conditions of the yd but also following the rapid deglaciation and transition to warmer conditions that followed the end of the yd surprisingly there is a paucity last glacial maximum lgm coral ages implying they were largely absent during this period when cold water conditions were more prevalent radiocarbon ages show that the intermediate depth waters of the mediterranean generally had 14 c compositions similar to surface waters indicating that these waters were extremely well ventilated the only exception is a narrow period in the yd 12 500 100 years bp when several samples of lophelia pertusa from the ionian sea had 14 c values falling significantly below the marine curve using a refined approach isolation ages isol of 300 years to 500 years are estimated for these intermediate 800 1000 m depth waters relative to surface marine waters indicating a reduction or absence of deep water formation in the ionian and adjacent adriatic seas during the yd contrary to previous findings we find no evidence for widespread intrusion of low 14 c atlantic waters into the mediterranean prolific growth of deep sea corals in the mediterranean ended abruptly at 10 900 years bp with many of the coral bearing mounds on the continental slopes being draped in a thin veneer of mud their demise is attributed to a number of factors including the direct loss of habitat due to high sedimentation that accompanied glacial meltwater pulses together with rising temperatures that would have finally pervaded the deeper water of the mediterranean following the onset of holocene warming

the reshaping of the south west adriatic margin by cascading of dense shelf waters abstract the south west adriatic margin sam includes a steep and morphologically complex continental slope stretching about 600 km from the pelagosa sill to the otranto strait the margin is clearly dissected by submarine slides active fault systems e g the gondola deformation belt numerous shallowly incised and relatively straight canyons located south of bari canyon and a variety of large scale erosional and depositional features this area is seasonally impacted by dense shelf water forming in the north adriatic through wind forced winter cooling moving south along the western side of the basin and cascading across the south adriatic slope the area has been investigated through multibeam surveys integrated by high resolution seismic stratigraphic data resolving glacial and post glacial deposits this paper gives a detailed and comprehensive description of the sam seafloor morphology to document how the process of dense shelf water cascading concurs to a thorough restyling of the submarine landscape by interacting with the pre existing and markedly differentiated morphologies and sediment distribution we focus on depositional and erosional features such as giant sediment drifts down to 1200 m water depth muddy and sandy sediment waves comet marks against pre existing slide blocks furrow fields against steep slopes large scours at the shelf edge and large erosional moats adjacent to major morphological barriers the analysis of the bedform orientation and spatial distribution indicates that the downslope cascading bottom currents dominantly directed to the se encounter a straight upper slope oriented north south in the north and progressively more east west proceeding to the south as the slope orientation becomes more e w it also appears more dissected by small scale canyons active during glacial times in the latter area therefore the dense shelf waters follow a slope parallel direction almost perpendicular to the pre existing slope canyons as a consequence erosional furrows develop perpendicular to the canyon flanks and some of the canyon heads become disconnected from the main canyon downslope

cascades of dense water around the world ocean dense water overflow off continental shelves cascading is one of the contributing processes of shelf deep ocean exchange and of topical interest to climate studies and nutrient fluxes dense water originating from cooling evaporation freezing and salinization on a shallow shelf spills over the shelf edge and may develop as near bottom gravity current or an intermediate depth intrusion it is difficult to observe in nature due to its intermittent character this paper provides an extensive inventory of observed cases of water cascades around the world ocean summarises their locations and individual properties and provides statistics of the identified cases the search for cascading was carried out using oceanographic databases and a literature review this study identified 61 confirmed cases world wide including 25 cases in the arctic seas 12 at mid latitudes seven in sub tropical and tropical regions and 17 off the antarctic shelves eighteen cascades had not been reported before we analyze a set of numerical parameters of dense water cascades allowing us to quantify compare and contrast the properties of water cascades the overall average density contrast between the confirmed cascades and ambient water is 0 37 kg m3 it can be as much as 2 kg m3 on some arctic shelves frequently initiated by strong cooling at the surface cascades often remain colder through the descent thus supplying the deep ocean with colder and fresher water in non dimensional variables the data from all climate zones fit well to a unique curve which represents a relationship between a cascade s internal structure and the parameters describing its forcing on average the down slope volumetric flux provided by dense water cascades is estimated as 0 05 to 0 08 sv per 100 km of shelf edge regional terms arctic antarctic north atlantic ocean barents sea mediterranean sea skagerrak tasman sea sea of okhotsk

stratigraphic framework of the apulian deep water coral province ionian sea abstract shallow sediment lithology and stratigraphy were investigated at selected areas off santa maria di leuca sml on the apulian margin between 350 and 1200 m water depth in order to define the sea bottom character on which coral mounds have developed according to existing geophysical data and in situ observations deep coral growth in the sml area creates patches of colonies typically settled on hard substrates on the upper flanks and or near the top of mound like structures and elongated ridges the sedimentary stratigraphy is strongly influenced by the local topography which is modeled by tectonic and geomorphological forcing large scale erosional features slope failure and sediment mass accumulation are evident from seismic investigations additionally sites of preferential sediment accumulation due to the action of bottom currents are identified as a result a complex sedimentary pattern characterizes this part of the apulian margin with strong lateral variability in sediment type and age although hemipelagic silty clay constitutes the main lithology there are sites characterized by periodic accumulation of silt and fine sand and local re deposition of coarse biogenic sand from the surrounding areas and from shallower depths excluding one site where mid pleistocene sediments are brought very close to the bottom surface due to wide scale erosion all collected sediments are late pleistocene to holocene in age and fall biostratigraphically within the emiliania huxleyi acme nannofossil zone reworking detected through nannofossil analysis is common in most cores excluding the ones taken from topographic highs and is variable in extent from site to site and within the sediment column it includes cretaceous to early pleistocene species suggesting provenance from extended successions or various stratigraphic levels outcropping on the submerged apulian margin or in adjacent land sections reworking is often associated with a high content of lithogenic particles and an increase in the coarser silt fraction coral debris was collected at many stations both at the sediment surface and within the stratigraphic sequence with varying abundance in relation to proximity to the coral colonies radiometric dating and micropaleontological analyses at some sites allow us to propose a sequence of coral colonization phases

further investigations on 150 km echoing riddle using simultaneous observations of 150 km and e region echoes from off electrojet location gadanki 1 in this paper we present a detailed study of the off electrojet daytime 150 km echoes based on simultaneous observations of daytime 150 km and e region echoes made on a few days per month during july 2005 to august 2006 using the gadanki radar daytime 150 km echoes are found to occur in all seasons over gadanki although echo occurrence is found to be maximum in equinoxes and minimum in summer no clear seasonal preference over gadanki has been observed in contrast e region echo occurrence made simultaneously shows a strong seasonal dependence with remarkably low occurrence in winter as compared to other seasons interestingly the 150 km echoes show a distinctly different morphology in winter as compared to other seasons echoes are observed in two distinct height regions in winter as compared to one broad region in other seasons also the strongest echo and the lowest altitude of echo occurrence are found to be associated with winter further a significant share of doppler velocities is found to be downward in winter as compared to predominantly upward velocities observed in other seasons no seasonal dependence in the spectral width of 150 km echoes however has been observed seasonally averaged doppler velocities are quite similar to those of the f region drifts reported from jicamarca again seasonally averaged drifts are found to be downward in winter afternoon as compared to upward velocities observed in other seasons notwithstanding the seasonal differences observed in the 150 km echoes echo occurrence is found to have a common feature of strong forenoon afternoon asymmetry with forenoon occurrence being greater these observations are discussed in the light of present understanding on the daytime 150 km echoing phenomenon

the impact of cascading currents on the bari canyon system sw adriatic margin central mediterranean abstract the bari canyon system bcs is a peculiar erosional depositional feature characterised by two main almost parallel conduits emanating from a broad crescent shaped upper slope region when viewed in cross sections parallel to the margin bcs appears markedly asymmetric with a right hand southern side that is higher and steeper about 800 m in relief and more than 30 steep the left hand side of the canyon is instead much smoother as a consequence bottom currents flowing along the slope from the north enter the canyon and interact with its complex topography leading to preferential deposition on the up current side of pre existing morphological relief where mass failure deposits generate morphologic relief outside the canyon sediment is preferentially deposited up current n ward bcs includes three main ew oriented sediment conduits canyon c to the south channel b in the central area and moat a in the north channel b shows a well developed levee deposit on its right hand side and appears markedly straight and erosional on the upper slope the deepest portion of channel b is substantially abandoned and draped but still shows a subdued thickening of the draped unit north and up current of pre existing morphologic relief confirming the impact of along slope flowing currents canyon c is flanked by erosional walls all the way to the basin floor where deep sea furrows develop with a nw se orientation today dense water formation in the adriatic is seasonally modulated and displays a significant variability on inter decadal scales dense water formation during glacial intervals was likely different from the modern because most of the north adriatic shelf was subaerially exposed and the deep water mixing in the south was likely reduced as suggested by paleoceanographic reconstructions the growth patterns of bcs since the lgm are characterised by concurrent erosion of the upper portion of channel b and of the lower portion of canyon c it is possible that flows through the straight narrow and steep upper segment of channel b spill over its right hand levee in ca 600 m water depth where the relief of levee b on the channel floor is minimal and enter canyon c where substantial erosion takes place in this view the upper portion of canyon c where hard grounds and corals are encountered is flushed by currents characterised by reduced turbidity while the lower part of canyon c collects additional flows from upper channel b

equatorial 150 km irregularities observed at pohnpei first observations of meter scale equatorial 150 km plasma irregularities outside the american longitude sector are reported the observations conducted at pohnpei western pacific with a wind profiling st radar demonstrate the feasibility of making ionospheric electric field measurements with low cost instruments and also reveal a potentially important anisotropy in the angular distribution of 150 km vhf radar echoes

on the linkage of daytime 150 km echoes and abnormal intermediate layer traces over sanya 1 the daytime 150 km echoes which are associated with the upper e region field aligned irregularities have been observed around the equatorial electrojet region but never before at magnetic latitudes near the northern anomaly crest region we present first results of daytime 150 km echo over sanya china a station located far away from the dip equator in the northern hemisphere a layer of weak radar echoes with spectral width less than 10 m s 1 was seen in the height range from 145 km at 12 15 lt to 152 km at 13 45 lt on 21 july 2010 the interesting aspect is that the rare observation of daytime 150 km echoes with the small sanya vhf radar was preceded by the occurrence of an unusual intermediate layer which is identified as abnormal traces at the upper e region in corresponding ionograms the abnormal intermediate layer associated with possible gravity wave activity that implicates the presence of upper e region density gradients could make a significant contribution to the growth of irregularities responsible for the rarely detected daytime 150 km echoes over sanya

a study of thermally induced convection near a high level nuclear waste repository in partially saturated fractured tuff we present simple estimates for velocities of buoyancy driven flow of liquid and gas phases near a hypothetical high level nuclear waste repository in partially saturated fractured tuff these estimates indicate that gas phase convection could take place with appreciable velocity of the order of 20 m year while liquid convection is expected to be very slow of the order of 0 1 mm year detailed numerical simulations using an effective continuum approximation to represent fracture effects confirm these estimates and demonstrate a sensitivity of gas convection to the strength of binary diffusion

on the sheet like nature of 150 km f1 radar echoes 1 the so called 150 km or f1 echoes are shown to arise from field aligned irregularities fai that are embedded in a sheet like region using a 49 92 mhz radar on christmas island which has an antenna beam directed toward geographic east at a zenith angle of 29 5 high resolution doppler velocity variations within the radar scattering volume are used to infer that the sheet like region could have both tilt and curvature this finding is used to infer that plasma density n must be enhanced within the sheet like region and that fai could be generated by an interchange instability driven by a vertical electric field or a zonal neutral wind that acts on the horizontal component of the gradient in n how tilted sheet like structures could form in the f1 region is discussed

daytime 150 km echoes observed with the equatorial atmosphere radar in indonesia first results 1 results of the daytime 150 km echoes from 10 36 s magnetic latitude observed using the equatorial atmosphere radar ear which are first of its kind from magnetic southern hemisphere are presented the echoing region of 145 165 km shows forenoon descent and afternoon ascent with signal intensity modulation with time resembling a necklace and the doppler spectra are narrow which are quite similar to those reported earlier from other locations westward and upward southward irregularity drifts are found to be consistent with daytime background electric fields providing a tool to investigate low latitude daytime electrodynamics detectability of these echoes suggests the absence of strong latitudinal dependence in contrast to the earlier belief suggesting a possibility of their detection at mid latitudes also the echoes show zonal anisotropy that is opposite to that observed over pohnpei the implications of these observations are discussed in the light of present understanding of 150 km echoing phenomenon

geochemical variations in quaternary hardgrounds from the hellenic trench region and possible relationship to their tectonic setting abstract the progressive lithification of quaternary hardgrounds forming in the hellenic trench region of the eastern mediterranean is documented by increasing 18o values and high magnesium calcite contents which reflect cold penesaline waters the presence of aragonite and dolomite in hardgrounds from the strabo trench which are also enriched in 12c indicates that the diagenetic solutions vary locally the origin of this unusual mineralogy and carbon isotopic content could be explained by the upward migration of brines from the underlying messinian evaporites and the subsurface oxidation of 12c enriched organic material shallow burial of the evaporites in the strabo trench a region dominated by transcurrent motion as opposed to deeper burial in the matapan and poseidon trench regions dominated by subduction and thrusting motion could be responsible for geochemical variations in the diagenetic solutions

high resolution bathymetry and acoustic geophysical data from santa maria di leuca cold water coral province northern ionian sea apulian continental slope abstract a total of 800 km 2 of multibeam echo sounder coverage roughly 800 km of chirp sonar data and 18 km of side scan sonar profiles 100 500 khz were acquired a few km offshore santa maria di leuca south eastern italy from 200 m to 1300 m water depth the explored area belongs to the upper slope of the gently south eastward dipping apulian continental margin northern ionian sea acoustic datasets were collected by three different oceanographic expeditions where evidence of living cold water coral cwc colonies were documented by previous surveys and samples high resolution multibeam bathymetry indicated an extensive rough seafloor with an irregular faulted upper surface to the west reflecting large scale tectonic control on the margin and a highly disrupted upper slope formed by prominent downslope mass movements to the north a broad area in the east was influenced by mass transport deposition which resulted in a very complex hummocky seafloor mainly shaped by detached block like features and failure related bedforms i e low scarps downslope lineations and compressional ridges from the shallow seismic stratigraphic data failure events appeared to be multiple and recurrent and chaotic reflectors both buried and exposed at the seafloor affected most of the investigated area drift sedimentation was also recognised along a central large ridge resulting in an interplay between contour currents and downslope turbidity currents the spatial distribution of the cwc reefs was inferred from the acoustic facies interpretation based on video images and ground truthed by sediment samples it appeared that 1 within the investigated area living coral frameworks were located along large topographic highs facing the main flow of the bottom currents where hard and firm substrata and or failure related sediment bedforms occurred 2 cwc mainly settled on clustered and isolated mound like features tens to a few hundreds of metres long and no more than 25 m high and were located between 600 and 900 m water depth within the broad area affected by downslope mass transport deposits such mound like morphologies could thus be interpreted as a result of sediment accreted by coral growth with the consequent sediment trapping on small scale positive seafloor irregularities formed by different types of pleistocene exposed mass transport deposits their burial prevented by bottom currents

dynamics of particles along the western margin of the southern adriatic processes involved in transferring particulate matter to the deep basin abstract the southern adriatic is an area of dense shelf water dsw cascading and open ocean convection the impact of dsw cascading events in transferring organic matter to the deep benthic community and in producing a wide range of bedforms along the continental margin has been highlighted in recent years in order to improve our knowledge on the interannual variability of the dsw cascading with the ultimate goal to understand timing of dsw formation and transport as well as the cascading process its variability in intensity and duration and the ultimate impact of the dense water on the deep sea in march 2009 we deployed an instrumented mooring in a field of sediment waves 860 m depth located down current to the bari canyon in march 2010 a second mooring was installed in the northern channel of the canyon winters 2009 2010 and 2011 were mild and particularly wet and the po river discharge remained relatively high throughout the whole winter hence we expected weak dense shelf water formation associated with a shallow shelf water overflowing off the adriatic shelf by contrast in winter 2012 the north adriatic experienced a severe cold wave with ne bora winds and reduced fresh water input these weather conditions allowed the formation of extremely dense shelf water three additional moorings were quickly deployed during this cold event in the southern adriatic sea to investigate the spatial variability of particle and organic matter fluxes exiting from the adriatic continental shelf under the influence of a strong dsw cascading event slow near bottom currents never exceeding 40 cm s 1 were recorded between march 2009 and february 2012 water temperatures depicted minor negative shifts total mass fluxes tmfs were low annual avg 1 7 2 8 g m 2 d 1 and 0 3 0 6 g m 2 d 1 in the canyon and in the sediment wave field respectively and peak values 6 8 g m 2 d 1 but showed significant seasonal and interannual variability fluxes in the canyon were higher than those measured in the sediment wave field at deeper water depth mass flux peaks during the 2112 dsw cascading were up to 5 times higher than the peaks of previous years up to 18 70 g m 2 d 1 with a spatial variability mainly driven by the localized pathways of dsw cascading in the canyon near bottom currents exceeded 70 cm s 1 and temperature dropped to 12 2 c while current speeds were high also at 1200 m depth 60 cm s 1 in the moat surrounding the dauno seamount surprisingly mass flux peaks occurred from the 16th february to the 1st of march 3 4 weeks ahead of the usual dsw occurrence suggesting an early arrival of the dsw the deep dsw cascading was the main process driving the particle transfer across the southern adriatic margin during late winter spring 2012 mooring data showed a nw se gradient of temperature and kinetic energy from upslope to basin floor indicating slope transverse flow modulated by local obstruction caused by the rugged seafloor topography bari canyon is one of the sites of dsw flow and in this area we have the possibility to extend observations back in time using continuous mooring data since 2009 and previous published materials this approach allowed evaluation of additional mechanisms of particle transport e g open ocean convection storm driven downward transport shallow dense water cascading that are particularly relevant in years when the dsw formation is less vigorous and cascading processes are sluggish the small amplitude of total mass flux peaks the weak currents and the relatively high and constant temperatures recorded during 2009 2010 and 2011 springs are consistent with an enhanced vertical particle rain from a mid water nepheloid layer triggered in turn by a shallow cascading of not particularly dense shelf water detaching from the seafloor when reaches its neutral buoyancy thus the intensity of dsw cascading shallow vs deep plays a first order control on the particulate fluxes through the western margin of the southern adriatic while storm induced sediment transport can occasionally be relevant too