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22 pages, 12 figures, 2 tables.-- Dataset https://doi.org/10.20350/digitalCSIC/13748, Increases of water turbidity and suspended sediment transport in submarine canyons have been associated with high-energy events such as storms, river floods and dense shelf water cascading (DSWC), and occasionally with bottom trawling along canyon flanks and rims. To assess the variations on the water column turbidity and sediment transport in the Palamós Canyon linked to both natural and trawling-induced processes, an autonomous hydrographic profiler, as well as a near-bottom current meter and a turbidimeter were deployed in the canyon axis (929 m depth) from February to June 2017, covering a trawling closure (February) and trawling activities (March-June). Periods of enhanced water turbidity during the trawling closure were mostly associated with storms and DSWC events, transporting turbid dense waters into the canyon. In absence of such events, the water column displayed low suspended sediment concentrations (~ 0.3 mg L− 1) until the trawling season began, when particulate matter detachments, ranging between > 1 mg L− 1 and 3.8 mg L− 1, were observed at the water depths where the trawling grounds are found. During the trawling closure, high near-bottom suspended sediment fluxes (35–44 g m− 2 s− 1) were sporadically registered at ~ 920 m depth associated with a major storm and DSWC event. Smaller but more frequent increases of near-bottom suspended sediment fluxes (0.1–1.4 g m− 2 s− 1) were recorded during trawling activities. Despite these smaller trawling-induced suspended sediment fluxes, 30 days of continuous bottom trawling activity transported a total amount of 40 kg m− 2, of similar magnitude to that generated by a major DSWC event (50 kg m− 2). Since bottom trawling in Palamós Canyon is practiced on a daily basis throughout the year, a much larger contribution of anthropogenically derived water turbidity and suspended sediment transport can be expected, This work has been supported by the ABIDES (CTM2015-65142) Spanish Project and by the autonomous government of Catalonia grants 2017 SGR 863 and 2017 SGR 1241, as well as by the TrawledSeas Project receiving funding from the European Union’s Horizon 2020 Research and Innovation programme under a MSCA grant agreement (No. 867471). M. Arjona-Camas is supported by a predoctoral FPI grant from the Spanish Ministry of Economy, Industry and Competitiveness, With the institutional support of the ‘Severo OchoaCentre of Excellence’ accreditation (CEX2019-000928-S)

6 pages, 5 figures, In order to study sediment accumulation rates in the Palamós submarine canyon (Northwestern Mediterranean) during the last century, three sediment cores were extracted from the canyon axis at depths of 450, 1200 and 1750 m respectively, where instrumented moorings were previously located. Estimated sedimentation rates based on 210Pb and 137Cs profiles suggest that the contemporary trends of sediment transfer and accumulation in the canyon may be different from secular trends. During the seventies, a two-fold increase of the sediment accumulation rate took place at the 1750 m depth site. This change has been associated to trawling activities and is attributed to the rapid technical development that the local trawling fleet underwent during the seventies. The surroundings and rims of submarine canyons are frequently targeted by commercial trawling fisheries, an activity that may enhance the input of resuspended particles into canyons, and eventually trigger sediment gravity flows. Our results suggest that the effects of trawling over the dynamics of the seafloor may extend further and deeper from the fishing grounds, eventually extending to bathyal depths. Hence the anthropogenic influence on the sedimentary budget of some deep submarine environments may be more important than previously thought, This study was conducted within the CANYONS project, funded by “Dirección General de Enseñanza Superior e Investigación Científica” (MAR99-1060-CO3-01, 02 and 03). J. Martín was funded by the Spanish Ministry of Education and Science (MEC) through a FPI scholarship and later by the HERMES Project (Contract no.: 511234-2, EU Sixth Framework Programme: Global Change and Ecosystems). 210Pb analysis of sediment samples was conducted at the School of Oceanography (University of Washington) by kind invitation of C.A. Nittrouer. C. Bas, J.B. Company and F. Maynou from ICM-CSIC provided important clues in the quest for fisheries data

26 pages, 14 figures, From March to November 2001, six current meters equipped with turbidimeters were moored 12 meters above the bottom inside the Palamós submarine canyon and on the adjacent slope. Horizontal particle fluxes were calculated from current and suspended sediment concentration data. This work aims to evaluate the advective sediment fluxes taking place in the Palamós canyon region, and to discern the nature and time-scales of the processes involved in the across-margin transfer of particles over the study period. Near-bottom currents inside the canyon were constrained by the local topography and displayed a high spatio-temporal variability. The net near-bottom transport of suspended matter in the canyon was largely driven by sharp increases of sediment load and current speed, most of them attributed to sediment gravity flows. These energetic events dominated over the current-driven sediment transport, which was relatively weak due to periodical up-canyon/downcanyon inversions along the canyon axis, and to complex current patterns and the presence of low sediment loads for most of the time at the other sites. During this 8-month experiment, the mid-canyon (>1200 m depth) acted as a by-pass zone, while at the canyon head, net sediment transport was directed persistently up-canyon. These patterns were further heightened during a major storm in November 2001. However, in this particular submarine canyon, substantial sedimentary activity and offshore export of particulate matter also occur in the absence of significant external forcings (storms, river floods). Human activities (deep trawling) induced sediment gravity flows during the dry and calm season (spring-summer) and enhanced the offshore transfer of particles during this time period, This work was carried out in the framework of the CANYONS project funded by the Spanish National R+D Plan. The first author was funded during this study by an FPI fellowship from the Spanish Ministry of Science and Technology (MCYT)

23 pages, 5 tables, 11 figures, To study the temporal and spatial variability of downward particle fluxes in the Palamós submarine canyon, seven sediment traps were moored inside and in the vicinity of the canyon from March to November 2001. Total mass fluxes, major constituent (organic carbon, opal, calcium carbonate and lithogenics) contents and fluxes, and 210Pb activity of particulate matter were obtained from two consecutive deployments at intervals of 10 and 12 days, respectively. Downward particle fluxes measured at the Palamós canyon head were 2 to 9 times higher than those measured in other northwestern Mediterranean canyons, and this relation increased drastically at 1200 m depth, where observed particle fluxes were 1 to 2 orders of magnitude higher than those reported in other surrounding canyons at similar depths. The highest near-bottom downward particle fluxes were not recorded in the canyon head but in the mid-canyon axis during late spring/summer, as a result of sediment gravity flows triggered by trawling activities at the canyon rims. In comparison to the adjacent open slope, Palamós Canyon is a prime site for the focusing and across-margin transference of total and organic matter. Off-shelf sediment transport was enhanced during a severe storm in November 2001, when a sharp increase in downward particulate fluxes was observed in the whole canyon both near the bottom and at intermediate waters. Despite the dominance of lithogenic particles all year round, a siliceous bloom affected the whole study area in March–April. An asymmetrical pattern was observed between the north and south canyon walls, with higher mean downward fluxes in the latter case, a fact related to the flow regime inside the canyon. The spatial–temporal distribution of total mass fluxes and major constituents defined two domains in the Palamós Canyon: an “inner” domain (up to 1200 m depth) constricted by the canyon topography and mainly influenced by a lateral transport of particles resuspended from the adjoining shelf and upper slope, and an “outer” domain, where slope dynamics and seasonal trends are more important in determining the composition and amount of downward particulate fluxes, This work was carried out in the framework of the CANYONS project, funded by the “Dirección General de Enseñanza Superior e Investigación Científica” (MAR99-1060-CO3-01, 02 and 03). 210Pb analysis of sediment trap samples was conducted in the laboratories at the School of Oceanography (University of Washington) by courtesy of Dr. C.A. Nittrouer. We thank to the officers and crew of R/V Garcia del Cid, for their help during the deployment operations