Role of Dense Shelf Water Cascading in the Transfer of Organochlorine Compounds to Open Marine Waters

9 pages, 4 figures, 2 tablesSettling particles were collected by an array of sediment trap moorings deployed along the Cap de Creus (CCC) and Lacaze-Duthiers (LDC) submarine canyons and on the adjacent southern open slope (SOS) between October 2005 and October 2006. This array collected particles during common settling processes and particles transferred to deep waters by dense shelf water cascading (DSWC). Polychlorobiphenyls (PCBs), dichlorodiphenyltrichloroethane and its metabolites (DDTs), chlorobenzenes (CBzs)—pentachlorobenzene and hexachlorobenzene—and hexachlorocyclohexanes were analyzed in all samples. The results show much higher settling fluxes of these compounds during DSWC than during common sedimentation processes. The area of highest deposition was located between 1000 and 1500 m depth and extended along the canyons and outside them showing their channelling effects but also overflows of dense shelf water from these canyons. Higher fluxes were observed near the bottom (30 m above bottom; mab) than at intermediate waters (500 mab) which is consistent with the formation and sinking of dense water close to the continental shelf and main displacement through the slope by the bottom. DSWC involved the highest settling fluxes of these compounds ever described in marine continental slopes and pelagic areas, e.g., peak values of PCBs (960 ng·m–2·d–1), DDTs (2900 ng·m–2·d–1), CBzs (340 ng·m–2·d–1) and lindane (180 ng·m–2·d–1)We thank all participants and crews of R/V Garcia del Cid and R/V Universitatis for their help and dedication. We are deeply indepted to Nicole Delsaut (CEFREM) for the prepatation of the trap samples for analysis. This research was supported by the HERMES (GOCE-CT-2005-511234-1) and HERMIONE (FP7-ENV-2008-1-226354) research projects. Financial support from the GRACCIE consolider project (CSD2007-00067) is acknowledged. This work was also sponsored by research groups 2009SGR1178 and 2009SGR1305 from Generalitat de CatalunyaPeer reviewe

Sediment transport to the deep canyons and open-slope of the western Gulf of Lions during the 2006 intense cascading and open-sea convection period

An array of mooring lines deployed between 300 and 1900 m depth along the Lacaze-Duthiers and Cap de Creus canyons and in the adjacent southern open slope was used to study the water and sediment transport on the western Gulf of Lions margin during the 2006 intense cascading period. Deep-reaching cascading pulses occurred in early January, in late January and from early March to mid-April. Dense water and sediment transport to the deep environments occurred not only through submarine canyons, but also along the southern open slope. During the deep cascading pulses, temporary upper and mid-canyon and open slope deposits were an important source of sediment to the deep margin. Significant sediment transport events at the canyon head only occurred in early January because of higher sediment availability on the shelf after the stratified and calm season, and in late February because of the interaction of dense shelf water cascading with a strong E-SE storm. During the January deep cascading pulses, increases in suspended sediment concentration within the canyon were greater and earlier at 1000 m depth than at 300 m depth, whereas during the March-April deep cascading pulses sediment concentration only increased below 300 m depth, indicating resuspension and redistribution of sediments previously deposited at upper and mid-canyon depths. Deeper than 1000 m depth, net fluxes show that most of the suspended sediment left the canyon and flowed along the southern open slope towards the Catalan margin, whereas a small part flowed down-canyon and was exported basinward. Additionally, on the mid- and lower-continental slope there was an increase in the near-bottom currents induced by deep open-sea convection processes and the propagation of eddies. This, combined with the arrival of deep cascading pulses, also generated moderate suspended sediment transport events in the deeper slope regions

Why long term trawled red algae beds off Balearic Islands (western Mediterranean) still persist?

The bottom morphology, the surface sediments and the epibenthic community of two adjacent areas within the fishing ground traditionally known as Pesquera Rica (Balearic Islands) were characterized using multibeam echosounder, van Veen dredge and beam trawl. Red algae beds predominate in both areas, but one has been exploited by trawling since at least 90 years ago, whereas the presence of natural barriers prevents this fishing activity in the other one. Comparisons between the two areas showed a biomass reduction of 46.8 and 39.3% of dominant red algae taxonomic groups Peyssonneliaceae and Corallinophycidae, respectively, in the trawled area (TA). Similarly, both mean abundance and biomass of most groups of fauna were higher in the not trawled area (NTA). N90 biodiversity index showed higher mean values of algae species in NTA than in TA (7.0 and 4.9, respectively), whereas no differences were detected neither for sessile nor for mobile fauna. SIMPER analysis showed that large species of both sessile and mobile epibenthic fauna (e.g. the ascidia Polycarpa mamillaris and the echinoderm Spatangus purpureus, respectively) presented higher abundance and contribution to within area similarity in NTA than in TA. In coincidence, these are the most abundant epibenthic species in the commercial hauls from the Pesquera Rica. The relatively low fishing effort and the gears used, addressed to avoid large catches of algae allowing longer hauls, may explain the subsistence of red algae beds in the Balearic Islands trawl fishing grounds. However, the detrimental effects shown here claim for urgent management measures aiming to preserve these bedsVersión del edito

Knowledge Graphs Evolution and Preservation -- A Technical Report from ISWS 2019

One of the grand challenges discussed during the Dagstuhl Seminar "Knowledge Graphs: New Directions for Knowledge Representation on the Semantic Web" and described in its report is that of a: "Public FAIR Knowledge Graph of Everything: We increasingly see the creation of knowledge graphs that capture information about the entirety of a class of entities. [...] This grand challenge extends this further by asking if we can create a knowledge graph of "everything" ranging from common sense concepts to location based entities. This knowledge graph should be "open to the public" in a FAIR manner democratizing this mass amount of knowledge." Although linked open data (LOD) is one knowledge graph, it is the closest realisation (and probably the only one) to a public FAIR Knowledge Graph (KG) of everything. Surely, LOD provides a unique testbed for experimenting and evaluating research hypotheses on open and FAIR KG. One of the most neglected FAIR issues about KGs is their ongoing evolution and long term preservation. We want to investigate this problem, that is to understand what preserving and supporting the evolution of KGs means and how these problems can be addressed. Clearly, the problem can be approached from different perspectives and may require the development of different approaches, including new theories, ontologies, metrics, strategies, procedures, etc. This document reports a collaborative effort performed by 9 teams of students, each guided by a senior researcher as their mentor, attending the International Semantic Web Research School (ISWS 2019). Each team provides a different perspective to the problem of knowledge graph evolution substantiated by a set of research questions as the main subject of their investigation. In addition, they provide their working definition for KG preservation and evolution

Biogeoquímica dels fluxos de partícules en canyons submarins de la Mediterrània nord-occidental: els efectes de les cascades d'aigües denses de plataforma

[cat] L‘estudi dels fluxos de partícules té per objectiu quantificar el carboni que s‘exporta cap a l‘oceà profund, el qual controla el segrest de CO2 atmosfèric a llarg termini. Els marges continentals juguen un paper important en aquest cicle oceànic, ja que són una bomba de carboni i nutrients entre l‘ecosistema terrestre i l'interior de l'oceà. En aquest treball s‘ha investigat la transferència de material al llarg del marge continental del golf de Lleó. Aquest mar-ge, situat al nord-oest de la Mediterrània occidental, està format per una ampla plataforma que s‘estén fins a un talús solcat per un gran nombre de canyons submarins. La major part dels sediments que entren al golf de Lleó provinents dels rius o resuspesos de la plataforma, circulen cap al sud-oest empesos per la circulació ciclònica de la massa d‘aigua i són deflectits majoritàriament a través dels canyons submarins més occidentals (canyons de Cap de Creus i Lacaze-Duthiers) cap a l‘interior de la conca. Aquest procés té lloc sobretot durant les tempestes marines d‘hivern i durant els esdeveniments de cascades submarines. L‘objectiu d‘aquest treball és estudiar la variabilitat temporal i espacial dels fluxos de partícules així com l‘origen i el grau de degradació de la matèria orgànica dins els canyons de Lacaze-Duthiers i Cap de Creus i al talús de la zona més meridional del golf de Lleó. La mesura directa dels fluxos ha estat possible gràcies al fondeig de línies instrumentades dotades amb trampes de sediments i correntímetres al llarg de tres transsectes. Les dades obtingudes indiquen que hi ha una ràpida resposta del sistema als forçaments físics. Així, es detecta una forta relació entre els condicionants atmosfèrics (que desencadenen la cascada d‘aigua densa, les onades i les aportacions fluvials i atmosfèriques), la producció primària, i la quantitat i qualitat del material que sedimenta al llarg del marge continental. La cascada d‘aigua densa de plataforma continental (DSWC) enregistrada durant els mesos de gener, febrer i març de 2006, esdevé el principal factor que controla la sedimentació de partícules a la zona estudiada. Les aigües de la cascada que s‘enfonsen canyó avall, escapen de la constricció que suposa el canyó a la zona baixa, continuen el seu camí paral•leles a les isòbates, i afecten el talús superior. Aquest fet denota la capacitat de la cascada per conduir el material erosionat de la plataforma continental cap als canyons i dispersar-lo cap al talús sud. Per tant, la DSWC pot esdevenir un factor important en la sedimentació en els canyons, el talús i el fons de la conca de la Mediterrània nord-occidental. Independentment dels esdeveniments de DSWC, les parts altes dels canyons estan afectades per un continu intercanvi de material amb la plataforma. Per contra, la zona d‘oceà obert (les zones baixes dels canyons i el talús) rep l‘arribada de material de la plataforma només com a conseqüència directa de la DSWC, mentre que durant la resta de l‘any hi imperen condicions de calma amb el predomini de fluxos pelàgics. La DSWC va ser el principal factor que controlà l‘arriba de matèria orgànica tant marina com terrestre al sistema, amb la transferència de grans quantitats de matèria orgànica d‘orígen terrestre durant el gener de 2006 (provinent de dipòsits de la plataforma), i matèria orgànica d‘orígen marí durant març i abril de 2006 (provinent del bloom fitoplanctònic). Per tant, la dispersió del material orgànic marí i terrestre va ser controlat per les condicions energètiques que afavoriren la resuspensió i el transport mar endins del material de la plataforma. La matèria orgànica es degradà no només durant el seu transport al llarg dels canyons, sinó també a través de la columna d'aigua, abans d'arribar a la zona de convergència dels canyons i al talús obert. Tot i que les aportacions laterals de matèria orgànica de la plataforma adjacent predominaren durant els esdeveniments de DSWC, les aportacions provinents d‘esdeveniments esporàdics de producció primària i la constant advecció de material marí varen ser evidents durant períodes de condicions energètiques i fluxos baixos.[eng] Particle flux studies aim at quantifying the amount of carbon and other components that are exported into deep ocean, which controls the long term atmospheric CO2 sequestration. Continental margins play an important role in this oceanic cycle as they pump carbon and nutrients from aerial ecosystems to the interior of the ocean. This work analyzes the transference of material along the continental margin of the Gulf of Lion. This margin, located in the northwestern Mediterranean, is a broad platform that extends to a slope cut by a large number of submarine canyons. Most of the sediments entering the system by rivers or resuspension in the shelf travel to the southwest due to the cyclonic circulation where are deflected mainly through the Cap de Creus and Lacaze-Duthiers submarine canyons to the deep basin. This process occurs mainly during winter sea storms and dense shelf water cascading events. The pourpose of this study is to analyze the temporal and spatial variability of particle fluxes and the source and degree of degradation of the organic matter within the Lacaze-Duthiers and Cap de Creus submarine canyons and the southern slope, in the Gulf of Lion. Direct flux measurements has been carried out by the deployment of 9 in-strumented lines equipped with sediment traps and currentmeters along three transects along the axis of the Lacaze-Duthiers and Cap de Creus canyons and the southern slope. Data indicate that there is a quick response of the system to physical forcings, with a close relation among atmospheric drivers (that trigger the dense water cascade, waving and river and atmospheric inputs), primary production, and the quantity and quality of settling material across the continental margin. The severe dense shelf water cascading (DSWC) event observed during January-March 2006 was the main factor controlling the sedimentation in the studied area. The dense waters escaped the lower canyon where it widens to flow along the isobaths and impacted the southern open slope. This denotes the capacity of such events to funnel and spread southwardly shelf eroded material through canyons. Therefore DSWC may become an important factor for the sedimentation in the middle and lower slope of the northwestern Mediterranean. Upper and middle canyon was primarily affected by continuous cross-slope exchanges with the shelf. The deeper ones were less affected by horizontal transferences and shelf material arrived only associated to the DSWC event, whereas outside the DSWC period pelagic fluxes become a significant part of the total mass flux. The severe DSWC event controlled also the arrival of organic matter to the sea floor, with the transfer of large quantities of land derived organic matter in January 2006 (from shelf deposits), and marine derived organic matter in March-April 2006 (from the concomitant spring bloom). Therefore, the timing of the dispersion of both terrigenous and marine derived organic material was controlled by the energetic conditions that enhance the resuspension and offshore transport of material in the shelf. In addition, this organic matter was degraded not only during its transport along the canyons but also in the water column before reaching the canyon mouth and open slope, as indicated by trends in amino acid and chloropigment concentrations and compositions. Furthermore, although lateral input of organic matter from the adjacent shelf predominated during DSWC events, sporadic primary production events and constant advection of land derived material were also evident during low energy and low flux periods

Biogeoquímica dels fluxos de partícules en canyons submarins de la Mediterrània nord-occidental: Els efectes de les cascades d'aigües denses de plataforma

L‘estudi dels fluxos de partícules té per objectiu quantificar el carboni que s‘exporta cap a l‘oceà profund, el qual controla el segrest de CO2 atmosfèric a llarg termini. Els marges continentals juguen un paper important en aquest cicle oceànic, ja que són una bomba de carboni i nutrients entre l‘ecosistema terrestre i l'interior de l'oceà. En aquest treball s‘ha investigat la transferència de material al llarg del marge continental del golf de Lleó. Aquest mar-ge, situat al nord-oest de la Mediterrània occidental, està format per una ampla plataforma que s‘estén fins a un talús solcat per un gran nombre de canyons submarins. La major part dels sediments que entren al golf de Lleó provinents dels rius o resuspesos de la plataforma, circulen cap al sud-oest empesos per la circulació ciclònica de la massa d‘aigua i són deflectits majoritàriament a través dels canyons submarins més occidentals (canyons de Cap de Creus i Lacaze-Duthiers) cap a l‘interior de la conca. Aquest procés té lloc sobretot durant les tempestes marines d‘hivern i durant els esdeveniments de cascades submarines. L‘objectiu d‘aquest treball és estudiar la variabilitat temporal i espacial dels fluxos de partícules així com l‘origen i el grau de degradació de la matèria orgànica dins els canyons de Lacaze-Duthiers i Cap de Creus i al talús de la zona més meridional del golf de Lleó. La mesura directa dels fluxos ha estat possible gràcies al fondeig de línies instrumentades dotades amb trampes de sediments i correntímetres al llarg de tres transsectes. Les dades obtingudes indiquen que hi ha una ràpida resposta del sistema als forçaments físics. Així, es detecta una forta relació entre els condicionants atmosfèrics (que desencadenen la cascada d‘aigua densa, les onades i les aportacions fluvials i atmosfèriques), la producció primària, i la quantitat i qualitat del material que sedimenta al llarg del marge continental. La cascada d‘aigua densa de plataforma continental (DSWC) enregistrada durant els mesos de gener, febrer i març de 2006, esdevé el principal factor que controla la sedimentació de partícules a la zona estudiada. Les aigües de la cascada que s‘enfonsen canyó avall, escapen de la constricció que suposa el canyó a la zona baixa, continuen el seu camí paral•leles a les isòbates, i afecten el talús superior. Aquest fet denota la capacitat de la cascada per conduir el material erosionat de la plataforma continental cap als canyons i dispersar-lo cap al talús sud. Per tant, la DSWC pot esdevenir un factor important en la sedimentació en els canyons, el talús i el fons de la conca de la Mediterrània nord-occidental. Independentment dels esdeveniments de DSWC, les parts altes dels canyons estan afectades per un continu intercanvi de material amb la plataforma. Per contra, la zona d‘oceà obert (les zones baixes dels canyons i el talús) rep l‘arribada de material de la plataforma només com a conseqüència directa de la DSWC, mentre que durant la resta de l‘any hi imperen condicions de calma amb el predomini de fluxos pelàgics. La DSWC va ser el principal factor que controlà l‘arriba de matèria orgànica tant marina com terrestre al sistema, amb la transferència de grans quantitats de matèria orgànica d‘orígen terrestre durant el gener de 2006 (provinent de dipòsits de la plataforma), i matèria orgànica d‘orígen marí durant març i abril de 2006 (provinent del bloom fitoplanctònic). Per tant, la dispersió del material orgànic marí i terrestre va ser controlat per les condicions energètiques que afavoriren la resuspensió i el transport mar endins del material de la plataforma. La matèria orgànica es degradà no només durant el seu transport al llarg dels canyons, sinó també a través de la columna d'aigua, abans d'arribar a la zona de convergència dels canyons i al talús obert. Tot i que les aportacions laterals de matèria orgànica de la plataforma adjacent predominaren durant els esdeveniments de DSWC, les aportacions provinents d‘esdeveniments esporàdics de producció primària i la constant advecció de material marí varen ser evidents durant períodes de condicions energètiques i fluxos baixos.Particle flux studies aim at quantifying the amount of carbon and other components that are exported into deep ocean, which controls the long term atmospheric CO2 sequestration. Continental margins play an important role in this oceanic cycle as they pump carbon and nutrients from aerial ecosystems to the interior of the ocean. This work analyzes the transference of material along the continental margin of the Gulf of Lion. This margin, located in the northwestern Mediterranean, is a broad platform that extends to a slope cut by a large number of submarine canyons. Most of the sediments entering the system by rivers or resuspension in the shelf travel to the southwest due to the cyclonic circulation where are deflected mainly through the Cap de Creus and Lacaze-Duthiers submarine canyons to the deep basin. This process occurs mainly during winter sea storms and dense shelf water cascading events. The pourpose of this study is to analyze the temporal and spatial variability of particle fluxes and the source and degree of degradation of the organic matter within the Lacaze-Duthiers and Cap de Creus submarine canyons and the southern slope, in the Gulf of Lion. Direct flux measurements has been carried out by the deployment of 9 in-strumented lines equipped with sediment traps and currentmeters along three transects along the axis of the Lacaze-Duthiers and Cap de Creus canyons and the southern slope. Data indicate that there is a quick response of the system to physical forcings, with a close relation among atmospheric drivers (that trigger the dense water cascade, waving and river and atmospheric inputs), primary production, and the quantity and quality of settling material across the continental margin. The severe dense shelf water cascading (DSWC) event observed during January-March 2006 was the main factor controlling the sedimentation in the studied area. The dense waters escaped the lower canyon where it widens to flow along the isobaths and impacted the southern open slope. This denotes the capacity of such events to funnel and spread southwardly shelf eroded material through canyons. Therefore DSWC may become an important factor for the sedimentation in the middle and lower slope of the northwestern Mediterranean. Upper and middle canyon was primarily affected by continuous cross-slope exchanges with the shelf. The deeper ones were less affected by horizontal transferences and shelf material arrived only associated to the DSWC event, whereas outside the DSWC period pelagic fluxes become a significant part of the total mass flux. The severe DSWC event controlled also the arrival of organic matter to the sea floor, with the transfer of large quantities of land derived organic matter in January 2006 (from shelf deposits), and marine derived organic matter in March-April 2006 (from the concomitant spring bloom). Therefore, the timing of the dispersion of both terrigenous and marine derived organic material was controlled by the energetic conditions that enhance the resuspension and offshore transport of material in the shelf. In addition, this organic matter was degraded not only during its transport along the canyons but also in the water column before reaching the canyon mouth and open slope, as indicated by trends in amino acid and chloropigment concentrations and compositions. Furthermore, although lateral input of organic matter from the adjacent shelf predominated during DSWC events, sporadic primary production events and constant advection of land derived material were also evident during low energy and low flux periods

Influence of the hydrodynamic conditions on the accessibility of Aristeus antennatus and other demersal species to the deep water trawl fishery off the Balearic Islands (western Mediterranean)

Monthly catches per unit of effort (CPUE) of adult red shrimp (. Aristeus antennatus), reported in the deep water bottom trawl fishery developed on the Sóller fishing ground off northern Mallorca (Western Mediterranean), and the mean ocean surface vorticity in the surrounding areas are compared between 2000 and 2010. A good correlation is found between the rises in the surrounding surface vorticity and the drops in the CPUE of the adult red shrimp. This correlation could be explained by assuming that most of the surface vorticity episodes could reach the bottom, increasing the seabed velocities and producing sediment resuspension, which could affect the near bottom water turbidity. A. antennatus would respond to this increased turbidity disappearing from the fishing grounds, probably moving downwards to the deeper waters. This massive displacement of red shrimp specimens away from the fishing grounds would consequently decrease their accessibility to fishing exploitation. Similar although more intense responses have been observed during the downslope shelf dense water current episodes that occurred in a submarine canyon, northeast of the Iberian peninsula. The proposed mechanism suggesting how the surface vorticity observed can affect the bottom sediments is investigated using a year-long moored near-bottom current meter and a sediment trap moored near the fishing grounds.The relationship between vorticity and catches is also explored for fish species (. Galeus melastomus, Micromesistius poutassou, Phycis blennoides) and other crustacean (. Geryon longipes and Nephrops norvegicus), considered as by-catch of the deep water fishery in the area. Results appear to support the suggestion that the water turbidity generated by the vorticity episodes is significant enough to affect the dynamics of the demersal species. © 2013 Elsevier B.V.This research has been partially sponsored by the IDEADOS project (CMT2008-04489-C03-01 and 03). The work of A. Amores has been funded by a JAE-PreDoc grant from Consejo Superior de Investigaciones Científicas (CSIC) and co-funded by Programa Operativo FSE 2007– 2013Peer reviewe

Organic carbon inputs to the sea bottom of the Mallorca continental slope

To assess the origin and degradation state of the organic particles sinking towards the sea bottom of the Mallorca continental slope, the major inorganic and organic components of the total mass flux and its biochemical compo- sition (in terms of protein, carbohydrate, lipid and phytopigment contents) have been analysed. Two instrument- ed lines were deployed at the western (Sóller station, Balearic sub-basin) and southern (Cabrera station, Algerian sub-basin) slopes of Mallorca Island, 900 m depth from November 2009 to January 2011. The two locations are characterized by putatively different environmental settings. Settled material at Sóller station has higher lithogenic contents when compared with the Cabrera one. Such difference can be explained by the synergistic presence in the Sóller station of large inputs of resuspended material due to the mesoscale variability of the Balearic current and the impact of bottom trapped waves. On the other hand, at the Cabrera station sinking particles are characterized by OM and opal percentages higher than those recorded at the Sóller station. This result points out that organic particles reaching the sea floor at the Cabrera station have a pre-eminent pelagic origin. Based on analyses of the C and N stable isotopes of the sinking material, our results also highlight that, overall, the OM reaching the sea floor at the Mallorca slope is mostly of marine origin. In general, the OM settled at the Sóller station has a higher nutritional value than that at the Cabrera one. Such a difference, occurring across a relatively reduced spatial scale, let us hypothesizing that the nutritionally richer particles descending in the Cabrera station are exposed to a less energetic environment than that in the Sóller setting. This would lead to higher settling velocity of particles in the Sóller setting which in turn would result in lower degradation rates of particles during their descent towards the sea bottom

Structure and dynamics of food webs along the water column in the western Mediterranean elucidated by stable nitrogen and carbon isotope data

Final workshop IDEADOS: The wrapping up of the IDEADOS project, International Workshop on Environment, Ecosystems and Demersal Resources and fisheries, 14-16 November 2012, Palma de Mallorca, SpainPeer reviewe