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Simon Jennings - One of the best experts on this subject based on the ideXlab platform.
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Article Modelling potential impacts of bottom trawl fisheries on soft sediment biogeochemistry in the North Sea{
2020Co-Authors: Daniel E Duplisea, Simon Jennings, S J Malcolm, Ruth Parker, D B SivyerAbstract:Bottom Trawling causes physical disturbance to sediments particularly in shelf areas. The disturbance due to Trawling is most significant in deeper areas with softer sediments where levels of natural disturbance due to wave and tidal action are low. In heavily fished areas, trawls may impact the same area of seabed more than four times per year. A single pass of a beam trawl, the heaviest gear routinely used in shelf sea fisheries, can kill 5-65% of the resident fauna and mix the top few cm of sediment. We expect that sediment community function, carbon mineralisation and biogeochemical fluxes will be strongly affected by Trawling activity because the physical effects of Trawling are equivalent to those of an extreme bioturbator, and yet, unlike bioturbating macrofauna, Trawling does not directly contribute to community metabolism. We used an existing box-model of a generalised soft sediment system to examine the effects of Trawling disturbance on carbon mineralisation and chemical concentrations. We contrasted the effects of a natural scenario, where bioturbation is a function of macrobenthos biomass, with an anthropogenic impact scenario where physical disturbance results from Trawling rather than the action of bioturbating macrofauna. Simulation results suggest that the effects of low levels of Trawling disturbance will be similar to those of natural bioturbators but that high levels of Trawling disturbance prevent the modelled system from reaching equilibrium due to large carbon fluxes between oxic and anoxic carbon compartments. The presence of macrobenthos in the natural disturbance scenario allowed sediment chemical storage and fluxes to reach equilibrium. This is because the macrobenthos are important carbon consumers in the system whose presence reduces the magnitude of available carbon fluxes. In soft sediment systems, where the level physical disturbance due to waves and tides is low, model results suggest that intensive Trawling disturbance could cause large fluctuations in benthic chemical fluxes and storage
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Assessing bottom Trawling impacts based on the longevity of benthic invertebrates
Journal of Applied Ecology, 2018Co-Authors: Jan G. Hiddink, Simon Jennings, Stefan G. Bolam, Ray Hilborn, Marija Sciberras, Giulia Cambiè, Robert A. Mcconnaughey, Tessa Mazor, Jeremy S. Collie, C. Roland PitcherAbstract:Bottom Trawling is the most widespread human activity directly affecting seabed habitats. Assessment and effective management of the effects of bottom Trawling at the scale of fisheries requires an understanding of differences in sensitivity of biota to Trawling. Responses to disturbance are expected to depend on the intrinsic rate of increase in populations (r), which is expected to be linearly related to the reciprocal of longevity. We examine the relationship between the longevity of benthic invertebrates and their response to bottom Trawling; both in terms of the immediate mortality following a trawl pass and their subsequent rates of recovery. We collate all available data from experimental and comparative Trawling studies, and test how longevity influences these aspects of sensitivity. The shortest lived organisms ( 1 year decreased by ~9% immediately following a trawl pass. The effect of bottom Trawling in comparative studies increased with longevity, with a 2–3× larger effect on biota living >10 years than on biota living 1–3 years. We attribute this difference to the slower recovery rates of the long-lived biota. The observed relationship between the intrinsic rate of population increase (r, our metric of recovery rate) and the reciprocal of longevity matches theoretical expectation and predicts that the sensitivity of habitats to bottom Trawling is higher in habitats with higher proportions of long-lived organisms. Synthesis and applications. Where the longevity of a species or the longevity distribution of a community is known or can be inferred, our estimates of depletion and intrinsic rate of increase can be combined with high-resolution maps of Trawling intensity to assess Trawling impacts at the scale of the fishery or other defined unit of assessment. Our estimates of r may also be used to estimate recovery times following other forms of seabed disturbance.
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global analysis of depletion and recovery of seabed biota after bottom Trawling disturbance
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Jan G. Hiddink, Adriaan D. Rijnsdorp, Simon Jennings, Marija Sciberras, Robert A. Mcconnaughey, Tessa Mazor, Claire L Szostek, Kathryn M Hughes, Nick Ellis, Ray HilbornAbstract:Bottom Trawling is the most widespread human activity affecting seabed habitats. Here, we collate all available data for experimental and comparative studies of Trawling impacts on whole communities of seabed macroinvertebrates on sedimentary habitats and develop widely applicable methods to estimate depletion and recovery rates of biota after Trawling. Depletion of biota and trawl penetration into the seabed are highly correlated. Otter trawls caused the least depletion, removing 6% of biota per pass and penetrating the seabed on average down to 2.4 cm, whereas hydraulic dredges caused the most depletion, removing 41% of biota and penetrating the seabed on average 16.1 cm. Median recovery times postTrawling (from 50 to 95% of unimpacted biomass) ranged between 1.9 and 6.4 y. By accounting for the effects of penetration depth, environmental variation, and uncertainty, the models explained much of the variability of depletion and recovery estimates from single studies. Coupled with large-scale, high-resolution maps of Trawling frequency and habitat, our estimates of depletion and recovery rates enable the assessment of Trawling impacts on unprecedented spatial scales.
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estimating high resolution trawl fishing effort from satellite based vessel monitoring system data
Ices Journal of Marine Science, 2007Co-Authors: Craig Mills, Simon Jennings, Sunny E Townsend, Paul D Eastwood, Carla A HoughtonAbstract:High resolution estimates of Trawling effort are needed to underpin studies of Trawling impacts on species, habitats, and ecosystem processes, and to monitor responses to area closure and other management actions. Satellite-based vessel monitoring systems (VMS) were designed for fishery control and enforcement, but they provide potentially valuable source information on spatial and temporal patterns of Trawling activity at multiple scales. Based on an analysis of VMS data for UK beam trawlers in the North Sea, a method is described for identifying Trawling activity and estimating fishing intensity based on the minimum and maximum potential spatial extent of Trawling effort from VMS data. The optimal method for identifying Trawling and steaming behaviour combined speed and directionality rules and correctly identified Trawling and steaming in 99% and 95% of cases, respectively. Using speed- and directionality-filtered VMS data, Trawling effort can be reported as area impacted per unit time per unit area at a range of grid scales from 1 km to 100 km (10 000 km2). Trawling effort is accurately represented at a grid cell resolution of 3 km or less.
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chronic bottom Trawling alters the functional composition of benthic invertebrate communities on a sea basin scale
Marine Ecology Progress Series, 2006Co-Authors: Simon Jennings, Jan G. Hiddink, H M Tillin, Michel J. KaiserAbstract:Bottom Trawling causes widespread physical disturbance of sediments in seas and oceans and affects benthic communities by removing target and non-target species and altering habitats. One aspiration of the ecosystem approach to management is to conserve function as well as biodiversity, but Trawling impacts on benthic community function need to be understood before they can be managed. Here we present the large scale and long term impact of chronic Trawling on the functional composition of benthic invertebrate communities using a comprehensive set of functional traits. The effects of chronic Trawling disturbance on the functional composition of faunal benthic invertebrate communities, as sampled with a small beam trawl, were investigated at 6 to 13 sites in each of 4 contrasting regions of the North Sea. Each site was subject to known levels of Trawling disturbance. Information on the life history and ecological function traits of the taxa sampled was translated into fuzzy coding and used to analyse the relationship between life history and functional roles within the ecosystem. Multivariate analyses were used to examine changes in the distribution of traits over gradients of Trawling intensity. Changes in the functional structure of the community due to the effects of long-term Trawling were identified in 3 of the 4 areas sampled. Filter-feeding, attached and larger animals were relatively more abundant in lightly trawled areas, while areas with higher levels of Trawling were characterised by a higher relative biomass of mobile animals and infaunal and scavenging invertebrates. Univariate analysis of selected traits confirmed the patterns observed in multivariate analysis. These results demonstrate that chronic bottom Trawling can lead to large scale shifts in the functional composition of benthic communities, with likely effects on the functioning of coastal ecosystems.
Jacobo Martín - One of the best experts on this subject based on the ideXlab platform.
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numerical modeling of bottom Trawling induced sediment transport and accumulation in la fonera submarine canyon northwestern mediterranean sea
Marine Geology, 2017Co-Authors: Jacobo Martín, Pere Puig, Miquel Canals, Marta Payopayo, Ricardo Silva Jacinto, Galderic Lastras, Marina Rabineau, Nabil SultanAbstract:Bottom Trawling leads to recurrent sediment resuspension events over fishing grounds. Recent studies have shown how bottom Trawling can drive seascape reshaping at large spatial scales and enhance sediment transport in submarine canyons, which subsequently impacts deep-sea ecosystems. Present knowledge on the transfer and accumulation of sediment flows triggered by bottom Trawling is based on localized and infrequent measurements whilst a more complete picture of the process is needed. The present work focuses on the modeling of sediment transport and accumulation resulting from Trawling activities in La Fonera submarine canyon, northwestern Mediterranean Sea, thus contributing to an improved assessment of Trawling impacts. Based on mooring data within a canyon gully, we use an inverse model to retrieve the unknown time series of resuspension due to Trawling over the fishing grounds. This resuspension is later used as forcing for the direct problem: we simulate Trawling-induced flows through the canyon and provide a 3D visualization of potential Trawling impacts on sediment dynamics, including the identification of the propagation patterns of sediments resuspended by Trawling. Flows coming from shallower fishing grounds are funneled through canyon flank gullies towards the canyon axis, with part of the resuspended sediment reaching the continental rise out of the canyon across the open continental slope. Trawling-induced sediment flows promote sediment accumulation beyond the canyon mouth. Given the wide geographical distribution of bottom Trawling, our results have far-reaching implications that go much beyond La Fonera submarine canyon. Our study represents a starting point for the assessment of the sedimentary impact of bottom Trawling in deep continental margins.
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chronic and intensive bottom Trawling impairs deep sea biodiversity and ecosystem functioning
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Antonio Pusceddu, Jacobo Martín, Pere Puig, Albert Palanques, Pere Masqué, Silvia Bianchelli, R DanovaroAbstract:Bottom Trawling has many impacts on marine ecosystems, including seafood stock impoverishment, benthos mortality, and sediment resuspension. Historical records of this fishing practice date back to the mid-1300s. Trawling became a widespread practice in the late 19th century, and it is now progressively expanding to greater depths, with the concerns about its sustainability that emerged during the first half of the 20th century now increasing. We show here that compared with untrawled areas, chronically trawled sediments along the continental slope of the north-western Mediterranean Sea are characterized by significant decreases in organic matter content (up to 52%), slower organic carbon turnover (ca. 37%), and reduced meiofauna abundance (80%), biodiversity (50%), and nematode species richness (25%). We estimate that the organic carbon removed daily by Trawling in the region under scrutiny represents as much as 60–100% of the input flux. We anticipate that such an impact is causing the degradation of deep-sea sedimentary habitats and an infaunal depauperation. With deep-sea Trawling currently conducted along most continental margins, we conclude that Trawling represents a major threat to the deep seafloor ecosystem at the global scale.
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Trawling induced daily sediment resuspension in the flank of a mediterranean submarine canyon
Deep-sea Research Part Ii-topical Studies in Oceanography, 2014Co-Authors: Jacobo Martín, Pere Puig, Albert Palanques, Marta RiboAbstract:Abstract Commercial bottom Trawling is one of the anthropogenic activities causing the biggest impact on the seafloor due to its recurrence and global distribution. In particular, Trawling has been proposed as a major driver of sediment dynamics at depths below the reach of storm waves, but the issue is at present poorly documented with direct observations. This paper analyses changes in water turbidity in a tributary valley of the La Fonera (=Palamos) submarine canyon, whose flanks are routinely exploited by a local Trawling fleet down to depths of 800 m. A string of turbidimeters was deployed at 980 m water depth inside the tributary for two consecutive years, 2010–2011. The second year, an ADCP profiled the currents 80 m above the seafloor. The results illustrate that near-bottom water turbidity at the study site is heavily dominated, both in its magnitude and temporal patterns, by Trawling-induced sediment resuspension at the fishing ground. Resuspended sediments are channelised along the tributary in the form of sediment gravity flows, being recorded only during working days and working hours of the Trawling fleet. These sediment gravity flows generate turbid plumes that extend to at least 100 m above the bottom, reaching suspended sediment concentrations up to 236 mg l−1 close to the seafloor (5 m above bottom). A few hours after the end of daily Trawling activities, water turbidity progressively decreases but resuspended particles remain in suspension for several hours, developing bottom and intermediate nepheloid layers that reach background levels ∼2 mg l−1 before Trawling activities resume. The presence of these nepheloid layers was recorded in a CTD+turbidimeter transect conducted across the fishing ground a few hours after the end of a working day. These results highlight that deep bottom Trawling can effectively replace natural processes as the main driving force of sediment resuspension on continental slope regions and generate increased near-bottom water turbidity that propagates from fishing grounds to wider and deeper areas via sediment gravity flows and nepheloid layer development.
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Effects of bottom Trawling on the Ebro continental shelf sedimentary system (NW Mediterranean)
Continental Shelf Research, 2014Co-Authors: Albert Palanques, Montserrat Demestre, Pere Puig, Jorge Guillén, Jacobo MartínAbstract:Abstract A monitoring effort to address the physical effects of bottom Trawling was conducted on the Ebro prodeltaic mud belt during the RESPONSE project. The monitoring was carried out for 14 months covering periods of different Trawling intensities and a close season for the Trawling fleet. The seabed morphology was studied by side-scan sonar and sediment texture and organic carbon content were analysed. Suspended sediment vertical distribution was recorded by CTD+turbidity hydrographic profiles and sediment transport was computed using time series from moored turbidimeters and current meters. The results show that the seabed of the fishing ground is strongly affected by scraping and ploughing induced by bottom Trawling. Part of the finer fraction of the prodeltaic mud resuspended by Trawling is winnowed, increasing the silt content of the settling sediment and also near-bottom turbidity. Sediment resuspended by Trawling is incorporated in the bottom nepheloid layer and transported across- and along-shelf, increasing sediment fluxes. Trawling also induces an increase in the organic carbon content in the bottom sediment. All these effects induced by Trawling have occurred during the last few decades, changing natural conditions in the fishing ground.
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organic biomarkers in deep sea regions affected by bottom Trawling pigments fatty acids amino acids and carbohydrates in surface sediments from the la fonera palamos canyon nw mediterranean sea
Biogeosciences, 2012Co-Authors: Elisabet Sane, Jacobo Martín, Pere Puig, Albert PalanquesAbstract:Deep-sea ecosystems are in general adapted to a limited variability of physical conditions, resulting in high vulnerability and slow recovery rates from anthropogenic perturbations such as bottom Trawling. Commercial Trawling is the most recurrent and pervasive of human impacts on the deep-sea floor, but studies on its consequences on the biogeochemistry of deep-sea sediments are still scarce. Pigments, fatty acids, amino acids and carbohydrates were analysed in sediments from the flanks of the La Fonera (Palamos) submarine canyon (NW Mediterranean Sea), where a commercial bottom Trawling fishery has been active for more than 70 yr. More specifically, we investigated how Trawling-induced sediment reworking affects the quality of sedimentary organic matter which reaches the seafloor and accumulates in the sediment column, which is fundamental for the development of benthic communities. Sediment samples were collected during two oceanographic cruises in spring and autumn 2011. The sampled sites included trawl fishing grounds as well as pristine (control) areas. We report that bottom Trawling in the flanks of the La Fonera Canyon has caused an alteration of the quality of the organic matter accumulated in the upper 5 cm of the seafloor. The use of a wide pool of biochemical tracers characterized by different reactivity to degradation allowed for us to discriminate the long-term effects of trawl-induced sediment reworking from the natural variability caused by the seasonal cycle of production and sinking of biogenic particles. Differences between untrawled and trawled areas were evidenced by labile amino acids, while differences between spring and autumn samples were detected only by the more labile indicators chlorophyll a and monounsaturated fatty acids. These results suggest that changes in the biochemical composition of the sedimentary organic matter caused by bottom Trawling can be more relevant than those associated with natural seasonality and pose serious concerns about the ecological sustainability of deep-sea Trawling activities.
Jan G. Hiddink - One of the best experts on this subject based on the ideXlab platform.
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Selection of indicators for assessing and managing the impacts of bottom Trawling on seabed habitats
Journal of Applied Ecology, 2020Co-Authors: Jan G. Hiddink, Ray Hilborn, Marija Sciberras, Robert A. Mcconnaughey, Tessa Mazor, Jeremy S. Collie, C. Roland Pitcher, Michel J. Kaiser, Ana M. Parma, Petri SuuronenAbstract:Bottom trawl fisheries are the most widespread source of anthropogenic physical disturbance to seabed habitats. Development of fisheries-, conservation- and ecosystem-based management strategies requires the selection of indicators of the impact of bottom Trawling on the state of benthic biota. Many indicators have been proposed, but no rigorous test of a range of candidate indicators against nine commonly agreed criteria (concreteness, theoretical basis, public awareness, cost, measurement, historical data, sensitivity, responsiveness, specificity) has been performed. Here, we collated data from 41 studies that compared the benthic biota in trawled areas with those in control locations (that were either not trawled or trawled infrequently), examining seven potential indicators (numbers and biomass for individual taxa and whole communities, evenness, Shannon–Wiener diversity and species richness) to assess their performance against the set of nine criteria. The effects of Trawling were stronger on whole-community numbers and biomass than for individual taxa. Species richness was also negatively affected by Trawling but other measures of diversity were not. Community numbers and biomass met all criteria, taxa numbers and biomass and species richness satisfied most criteria, but evenness and Shannon–Wiener diversity did not respond to Trawling and only met few criteria, and hence are not suitable state indicators of the effect of bottom Trawling. Synthesis and applications. An evaluation of each candidate indicator against a commonly agreed suite of desirable properties coupled with the outputs of our meta-analysis showed that whole-community numbers of individuals and biomass are the most suitable indicators of bottom Trawling impacts as they performed well on all criteria. Strengths of these indicators are that they respond strongly to Trawling, relate directly to ecosystem functioning and are straightforward to measure. Evenness and Shannon–Wiener diversity are not responsive to Trawling and unsuitable for the monitoring and assessment of bottom trawl impacts.
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Assessing bottom Trawling impacts based on the longevity of benthic invertebrates
Journal of Applied Ecology, 2018Co-Authors: Jan G. Hiddink, Simon Jennings, Stefan G. Bolam, Ray Hilborn, Marija Sciberras, Giulia Cambiè, Robert A. Mcconnaughey, Tessa Mazor, Jeremy S. Collie, C. Roland PitcherAbstract:Bottom Trawling is the most widespread human activity directly affecting seabed habitats. Assessment and effective management of the effects of bottom Trawling at the scale of fisheries requires an understanding of differences in sensitivity of biota to Trawling. Responses to disturbance are expected to depend on the intrinsic rate of increase in populations (r), which is expected to be linearly related to the reciprocal of longevity. We examine the relationship between the longevity of benthic invertebrates and their response to bottom Trawling; both in terms of the immediate mortality following a trawl pass and their subsequent rates of recovery. We collate all available data from experimental and comparative Trawling studies, and test how longevity influences these aspects of sensitivity. The shortest lived organisms ( 1 year decreased by ~9% immediately following a trawl pass. The effect of bottom Trawling in comparative studies increased with longevity, with a 2–3× larger effect on biota living >10 years than on biota living 1–3 years. We attribute this difference to the slower recovery rates of the long-lived biota. The observed relationship between the intrinsic rate of population increase (r, our metric of recovery rate) and the reciprocal of longevity matches theoretical expectation and predicts that the sensitivity of habitats to bottom Trawling is higher in habitats with higher proportions of long-lived organisms. Synthesis and applications. Where the longevity of a species or the longevity distribution of a community is known or can be inferred, our estimates of depletion and intrinsic rate of increase can be combined with high-resolution maps of Trawling intensity to assess Trawling impacts at the scale of the fishery or other defined unit of assessment. Our estimates of r may also be used to estimate recovery times following other forms of seabed disturbance.
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Estimating sensitivity of seabed habitats to disturbance by bottom Trawling based on the longevity of benthic fauna
Ecological Applications, 2018Co-Authors: Adriaan D. Rijnsdorp, Niels T Hintzen, Stefan G. Bolam, Clement Garcia, Jan G. Hiddink, P. Daniël Van Denderen, Tobias Van KootenAbstract:Bottom fishing such as Trawling and dredging may pose serious risks to the seabed and benthic habitats, calling for a quantitative assessment method to evaluate the impact and guide management to develop mitigation measures. We provide a method to estimate the sensitivity of benthic habitats based on the longevity composition of the invertebrate community. We hypothesize that long-lived species are more sensitive to Trawling mortality due to their lower pace of life (i.e. slower growth, late maturation). We analyse data from box-core and grab samples taken from 401 stations in the English Channel and southern North Sea to estimate the habitat-specific longevity composition of the benthic invertebrate community and of specific functional groups (i.e. suspension feeders and bioturbators), and examine how bottom Trawling affects the longevity biomass composition. The longevity biomass composition differed between habitats governed by differences in sediment composition (gravel and mud content) and tidal bed-shear stress. The biomass proportion of long-lived species increased with gravel content and decreased with mud content and shear stress. Bioturbators had a higher median longevity than suspension feeders. Trawling, in particular by gears that penetrate the seabed >2cm, shifted the community towards shorter-lived species. Changes from bottom Trawling were highest in habitats with many long-lived species (hence increasing with gravel content, decreasing with mud content). Benthic communities in high shear stress habitats were less affected by bottom Trawling. Using these relationships, we predicted the sensitivity of the benthic community from bottom Trawling impact at large spatial scale (the North Sea). We derived different benthic sensitivity metrics that provide a basis to estimate indicators of Trawling impact on a continuous scale for the total community and specific functional groups. In combination with high resolution data of Trawling pressure, our approach can be used to monitor and assess Trawling impact and seabed status at the scale of the region or broadscale habitat and to compare the environmental impact of bottom-contacting fishing gears across fisheries.
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global analysis of depletion and recovery of seabed biota after bottom Trawling disturbance
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Jan G. Hiddink, Adriaan D. Rijnsdorp, Simon Jennings, Marija Sciberras, Robert A. Mcconnaughey, Tessa Mazor, Claire L Szostek, Kathryn M Hughes, Nick Ellis, Ray HilbornAbstract:Bottom Trawling is the most widespread human activity affecting seabed habitats. Here, we collate all available data for experimental and comparative studies of Trawling impacts on whole communities of seabed macroinvertebrates on sedimentary habitats and develop widely applicable methods to estimate depletion and recovery rates of biota after Trawling. Depletion of biota and trawl penetration into the seabed are highly correlated. Otter trawls caused the least depletion, removing 6% of biota per pass and penetrating the seabed on average down to 2.4 cm, whereas hydraulic dredges caused the most depletion, removing 41% of biota and penetrating the seabed on average 16.1 cm. Median recovery times postTrawling (from 50 to 95% of unimpacted biomass) ranged between 1.9 and 6.4 y. By accounting for the effects of penetration depth, environmental variation, and uncertainty, the models explained much of the variability of depletion and recovery estimates from single studies. Coupled with large-scale, high-resolution maps of Trawling frequency and habitat, our estimates of depletion and recovery rates enable the assessment of Trawling impacts on unprecedented spatial scales.
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impacts of bottom fishing on the sediment infaunal community and biogeochemistry of cohesive and non cohesive sediments
Limnology and Oceanography, 2016Co-Authors: Marija Sciberras, Stefan G. Bolam, Ruth Parker, Claire Powell, Craig Robertson, Silke Kroger, Jan G. HiddinkAbstract:Bottom-trawl fisheries are wide-spread and have large effects on benthic ecosystems.We investigate the effect of scallop dredging on sand and otter Trawling on mud by measuring changes in the infaunal community and the biogeochemical processes which they mediate. We hypothesize that changes in biogeochemistry due to fishing will be larger in mud where macrofauna-mediated processes are expected to play a greater role, than in sand where hydrodynamics mediate the redox system. We sampled benthic infauna, sediment pore-water nutrients, oxygen, chlorophyll a (Chl a), apparent redox potential discontinuity layer, organic carbon and nitrogen content over a gradient of fishing intensity in sand and mud. The effects of fishing on biogeochemistry were stronger on mud than on sand, where biogeochemistry appeared to be more strongly influenced by tidal currents and waves. On mud, Trawling increased sediment-surface Chl a and ammonium concentration beyond 5 cm depth, but decreased ammonium and silicate concentration in the upper sediment layers. The effects of fauna and bioturbation potential on biogeochemistry were very limited in both mud and sand habitats. Our results suggests that otter Trawling may be affecting organic-matter remineralization and nutrient cycling through sediment resuspension and burial of organic matter to depth rather than through the loss of bioturbation potential of the benthic community. In conclusion, our hypothesis that the effects of Trawling on biogeochemistry are larger in mud is supported, but the hypothesis that these effects are mediated by changes in the infauna is not supported. These results imply that management of Trawling on muddy sediments should have higher priority.
Pere Puig - One of the best experts on this subject based on the ideXlab platform.
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numerical modeling of bottom Trawling induced sediment transport and accumulation in la fonera submarine canyon northwestern mediterranean sea
Marine Geology, 2017Co-Authors: Jacobo Martín, Pere Puig, Miquel Canals, Marta Payopayo, Ricardo Silva Jacinto, Galderic Lastras, Marina Rabineau, Nabil SultanAbstract:Bottom Trawling leads to recurrent sediment resuspension events over fishing grounds. Recent studies have shown how bottom Trawling can drive seascape reshaping at large spatial scales and enhance sediment transport in submarine canyons, which subsequently impacts deep-sea ecosystems. Present knowledge on the transfer and accumulation of sediment flows triggered by bottom Trawling is based on localized and infrequent measurements whilst a more complete picture of the process is needed. The present work focuses on the modeling of sediment transport and accumulation resulting from Trawling activities in La Fonera submarine canyon, northwestern Mediterranean Sea, thus contributing to an improved assessment of Trawling impacts. Based on mooring data within a canyon gully, we use an inverse model to retrieve the unknown time series of resuspension due to Trawling over the fishing grounds. This resuspension is later used as forcing for the direct problem: we simulate Trawling-induced flows through the canyon and provide a 3D visualization of potential Trawling impacts on sediment dynamics, including the identification of the propagation patterns of sediments resuspended by Trawling. Flows coming from shallower fishing grounds are funneled through canyon flank gullies towards the canyon axis, with part of the resuspended sediment reaching the continental rise out of the canyon across the open continental slope. Trawling-induced sediment flows promote sediment accumulation beyond the canyon mouth. Given the wide geographical distribution of bottom Trawling, our results have far-reaching implications that go much beyond La Fonera submarine canyon. Our study represents a starting point for the assessment of the sedimentary impact of bottom Trawling in deep continental margins.
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chronic and intensive bottom Trawling impairs deep sea biodiversity and ecosystem functioning
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Antonio Pusceddu, Jacobo Martín, Pere Puig, Albert Palanques, Pere Masqué, Silvia Bianchelli, R DanovaroAbstract:Bottom Trawling has many impacts on marine ecosystems, including seafood stock impoverishment, benthos mortality, and sediment resuspension. Historical records of this fishing practice date back to the mid-1300s. Trawling became a widespread practice in the late 19th century, and it is now progressively expanding to greater depths, with the concerns about its sustainability that emerged during the first half of the 20th century now increasing. We show here that compared with untrawled areas, chronically trawled sediments along the continental slope of the north-western Mediterranean Sea are characterized by significant decreases in organic matter content (up to 52%), slower organic carbon turnover (ca. 37%), and reduced meiofauna abundance (80%), biodiversity (50%), and nematode species richness (25%). We estimate that the organic carbon removed daily by Trawling in the region under scrutiny represents as much as 60–100% of the input flux. We anticipate that such an impact is causing the degradation of deep-sea sedimentary habitats and an infaunal depauperation. With deep-sea Trawling currently conducted along most continental margins, we conclude that Trawling represents a major threat to the deep seafloor ecosystem at the global scale.
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Trawling induced daily sediment resuspension in the flank of a mediterranean submarine canyon
Deep-sea Research Part Ii-topical Studies in Oceanography, 2014Co-Authors: Jacobo Martín, Pere Puig, Albert Palanques, Marta RiboAbstract:Abstract Commercial bottom Trawling is one of the anthropogenic activities causing the biggest impact on the seafloor due to its recurrence and global distribution. In particular, Trawling has been proposed as a major driver of sediment dynamics at depths below the reach of storm waves, but the issue is at present poorly documented with direct observations. This paper analyses changes in water turbidity in a tributary valley of the La Fonera (=Palamos) submarine canyon, whose flanks are routinely exploited by a local Trawling fleet down to depths of 800 m. A string of turbidimeters was deployed at 980 m water depth inside the tributary for two consecutive years, 2010–2011. The second year, an ADCP profiled the currents 80 m above the seafloor. The results illustrate that near-bottom water turbidity at the study site is heavily dominated, both in its magnitude and temporal patterns, by Trawling-induced sediment resuspension at the fishing ground. Resuspended sediments are channelised along the tributary in the form of sediment gravity flows, being recorded only during working days and working hours of the Trawling fleet. These sediment gravity flows generate turbid plumes that extend to at least 100 m above the bottom, reaching suspended sediment concentrations up to 236 mg l−1 close to the seafloor (5 m above bottom). A few hours after the end of daily Trawling activities, water turbidity progressively decreases but resuspended particles remain in suspension for several hours, developing bottom and intermediate nepheloid layers that reach background levels ∼2 mg l−1 before Trawling activities resume. The presence of these nepheloid layers was recorded in a CTD+turbidimeter transect conducted across the fishing ground a few hours after the end of a working day. These results highlight that deep bottom Trawling can effectively replace natural processes as the main driving force of sediment resuspension on continental slope regions and generate increased near-bottom water turbidity that propagates from fishing grounds to wider and deeper areas via sediment gravity flows and nepheloid layer development.
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Effects of bottom Trawling on the Ebro continental shelf sedimentary system (NW Mediterranean)
Continental Shelf Research, 2014Co-Authors: Albert Palanques, Montserrat Demestre, Pere Puig, Jorge Guillén, Jacobo MartínAbstract:Abstract A monitoring effort to address the physical effects of bottom Trawling was conducted on the Ebro prodeltaic mud belt during the RESPONSE project. The monitoring was carried out for 14 months covering periods of different Trawling intensities and a close season for the Trawling fleet. The seabed morphology was studied by side-scan sonar and sediment texture and organic carbon content were analysed. Suspended sediment vertical distribution was recorded by CTD+turbidity hydrographic profiles and sediment transport was computed using time series from moored turbidimeters and current meters. The results show that the seabed of the fishing ground is strongly affected by scraping and ploughing induced by bottom Trawling. Part of the finer fraction of the prodeltaic mud resuspended by Trawling is winnowed, increasing the silt content of the settling sediment and also near-bottom turbidity. Sediment resuspended by Trawling is incorporated in the bottom nepheloid layer and transported across- and along-shelf, increasing sediment fluxes. Trawling also induces an increase in the organic carbon content in the bottom sediment. All these effects induced by Trawling have occurred during the last few decades, changing natural conditions in the fishing ground.
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organic biomarkers in deep sea regions affected by bottom Trawling pigments fatty acids amino acids and carbohydrates in surface sediments from the la fonera palamos canyon nw mediterranean sea
Biogeosciences, 2012Co-Authors: Elisabet Sane, Jacobo Martín, Pere Puig, Albert PalanquesAbstract:Deep-sea ecosystems are in general adapted to a limited variability of physical conditions, resulting in high vulnerability and slow recovery rates from anthropogenic perturbations such as bottom Trawling. Commercial Trawling is the most recurrent and pervasive of human impacts on the deep-sea floor, but studies on its consequences on the biogeochemistry of deep-sea sediments are still scarce. Pigments, fatty acids, amino acids and carbohydrates were analysed in sediments from the flanks of the La Fonera (Palamos) submarine canyon (NW Mediterranean Sea), where a commercial bottom Trawling fishery has been active for more than 70 yr. More specifically, we investigated how Trawling-induced sediment reworking affects the quality of sedimentary organic matter which reaches the seafloor and accumulates in the sediment column, which is fundamental for the development of benthic communities. Sediment samples were collected during two oceanographic cruises in spring and autumn 2011. The sampled sites included trawl fishing grounds as well as pristine (control) areas. We report that bottom Trawling in the flanks of the La Fonera Canyon has caused an alteration of the quality of the organic matter accumulated in the upper 5 cm of the seafloor. The use of a wide pool of biochemical tracers characterized by different reactivity to degradation allowed for us to discriminate the long-term effects of trawl-induced sediment reworking from the natural variability caused by the seasonal cycle of production and sinking of biogenic particles. Differences between untrawled and trawled areas were evidenced by labile amino acids, while differences between spring and autumn samples were detected only by the more labile indicators chlorophyll a and monounsaturated fatty acids. These results suggest that changes in the biochemical composition of the sedimentary organic matter caused by bottom Trawling can be more relevant than those associated with natural seasonality and pose serious concerns about the ecological sustainability of deep-sea Trawling activities.
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chronic and intensive bottom Trawling impairs deep sea biodiversity and ecosystem functioning
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: Antonio Pusceddu, Jacobo Martín, Pere Puig, Albert Palanques, Pere Masqué, Silvia Bianchelli, R DanovaroAbstract:Bottom Trawling has many impacts on marine ecosystems, including seafood stock impoverishment, benthos mortality, and sediment resuspension. Historical records of this fishing practice date back to the mid-1300s. Trawling became a widespread practice in the late 19th century, and it is now progressively expanding to greater depths, with the concerns about its sustainability that emerged during the first half of the 20th century now increasing. We show here that compared with untrawled areas, chronically trawled sediments along the continental slope of the north-western Mediterranean Sea are characterized by significant decreases in organic matter content (up to 52%), slower organic carbon turnover (ca. 37%), and reduced meiofauna abundance (80%), biodiversity (50%), and nematode species richness (25%). We estimate that the organic carbon removed daily by Trawling in the region under scrutiny represents as much as 60–100% of the input flux. We anticipate that such an impact is causing the degradation of deep-sea sedimentary habitats and an infaunal depauperation. With deep-sea Trawling currently conducted along most continental margins, we conclude that Trawling represents a major threat to the deep seafloor ecosystem at the global scale.
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Trawling induced daily sediment resuspension in the flank of a mediterranean submarine canyon
Deep-sea Research Part Ii-topical Studies in Oceanography, 2014Co-Authors: Jacobo Martín, Pere Puig, Albert Palanques, Marta RiboAbstract:Abstract Commercial bottom Trawling is one of the anthropogenic activities causing the biggest impact on the seafloor due to its recurrence and global distribution. In particular, Trawling has been proposed as a major driver of sediment dynamics at depths below the reach of storm waves, but the issue is at present poorly documented with direct observations. This paper analyses changes in water turbidity in a tributary valley of the La Fonera (=Palamos) submarine canyon, whose flanks are routinely exploited by a local Trawling fleet down to depths of 800 m. A string of turbidimeters was deployed at 980 m water depth inside the tributary for two consecutive years, 2010–2011. The second year, an ADCP profiled the currents 80 m above the seafloor. The results illustrate that near-bottom water turbidity at the study site is heavily dominated, both in its magnitude and temporal patterns, by Trawling-induced sediment resuspension at the fishing ground. Resuspended sediments are channelised along the tributary in the form of sediment gravity flows, being recorded only during working days and working hours of the Trawling fleet. These sediment gravity flows generate turbid plumes that extend to at least 100 m above the bottom, reaching suspended sediment concentrations up to 236 mg l−1 close to the seafloor (5 m above bottom). A few hours after the end of daily Trawling activities, water turbidity progressively decreases but resuspended particles remain in suspension for several hours, developing bottom and intermediate nepheloid layers that reach background levels ∼2 mg l−1 before Trawling activities resume. The presence of these nepheloid layers was recorded in a CTD+turbidimeter transect conducted across the fishing ground a few hours after the end of a working day. These results highlight that deep bottom Trawling can effectively replace natural processes as the main driving force of sediment resuspension on continental slope regions and generate increased near-bottom water turbidity that propagates from fishing grounds to wider and deeper areas via sediment gravity flows and nepheloid layer development.
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Effects of bottom Trawling on the Ebro continental shelf sedimentary system (NW Mediterranean)
Continental Shelf Research, 2014Co-Authors: Albert Palanques, Montserrat Demestre, Pere Puig, Jorge Guillén, Jacobo MartínAbstract:Abstract A monitoring effort to address the physical effects of bottom Trawling was conducted on the Ebro prodeltaic mud belt during the RESPONSE project. The monitoring was carried out for 14 months covering periods of different Trawling intensities and a close season for the Trawling fleet. The seabed morphology was studied by side-scan sonar and sediment texture and organic carbon content were analysed. Suspended sediment vertical distribution was recorded by CTD+turbidity hydrographic profiles and sediment transport was computed using time series from moored turbidimeters and current meters. The results show that the seabed of the fishing ground is strongly affected by scraping and ploughing induced by bottom Trawling. Part of the finer fraction of the prodeltaic mud resuspended by Trawling is winnowed, increasing the silt content of the settling sediment and also near-bottom turbidity. Sediment resuspended by Trawling is incorporated in the bottom nepheloid layer and transported across- and along-shelf, increasing sediment fluxes. Trawling also induces an increase in the organic carbon content in the bottom sediment. All these effects induced by Trawling have occurred during the last few decades, changing natural conditions in the fishing ground.
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organic biomarkers in deep sea regions affected by bottom Trawling pigments fatty acids amino acids and carbohydrates in surface sediments from the la fonera palamos canyon nw mediterranean sea
Biogeosciences, 2012Co-Authors: Elisabet Sane, Jacobo Martín, Pere Puig, Albert PalanquesAbstract:Deep-sea ecosystems are in general adapted to a limited variability of physical conditions, resulting in high vulnerability and slow recovery rates from anthropogenic perturbations such as bottom Trawling. Commercial Trawling is the most recurrent and pervasive of human impacts on the deep-sea floor, but studies on its consequences on the biogeochemistry of deep-sea sediments are still scarce. Pigments, fatty acids, amino acids and carbohydrates were analysed in sediments from the flanks of the La Fonera (Palamos) submarine canyon (NW Mediterranean Sea), where a commercial bottom Trawling fishery has been active for more than 70 yr. More specifically, we investigated how Trawling-induced sediment reworking affects the quality of sedimentary organic matter which reaches the seafloor and accumulates in the sediment column, which is fundamental for the development of benthic communities. Sediment samples were collected during two oceanographic cruises in spring and autumn 2011. The sampled sites included trawl fishing grounds as well as pristine (control) areas. We report that bottom Trawling in the flanks of the La Fonera Canyon has caused an alteration of the quality of the organic matter accumulated in the upper 5 cm of the seafloor. The use of a wide pool of biochemical tracers characterized by different reactivity to degradation allowed for us to discriminate the long-term effects of trawl-induced sediment reworking from the natural variability caused by the seasonal cycle of production and sinking of biogenic particles. Differences between untrawled and trawled areas were evidenced by labile amino acids, while differences between spring and autumn samples were detected only by the more labile indicators chlorophyll a and monounsaturated fatty acids. These results suggest that changes in the biochemical composition of the sedimentary organic matter caused by bottom Trawling can be more relevant than those associated with natural seasonality and pose serious concerns about the ecological sustainability of deep-sea Trawling activities.
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effect of commercial Trawling on the deep sedimentation in a mediterranean submarine canyon
Marine Geology, 2008Co-Authors: Jacobo Martín, Pere Puig, Albert Palanques, Pere Masqué, Jordi GarciaorellanaAbstract:Abstract In order to study sediment accumulation rates in the Palamos 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 210 Pb and 137 Cs 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.
