Evidence of sediment gravity flows induced by trawling in the Palamós (Fonera) submarine canyon (northwestern Mediterranean)

Palanqués, Albert; Martín, Jacobo; Puig, Pere; Guillén, Jorge; Company, Joan B.; Sardà, Francisco

doi:10.1016/j.dsr.2005.10.003

Cited by 98 publications

(81 citation statements)

References 32 publications

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“…When these flows reach the main canyon axis, they are redirected seaward and further down-canyon, without affecting the southern canyons' flank, and accumulate the sediment load in the lower canyon reaches at depths of ≥1,800 m (17)(18)(19)30). Combined with the concurrent impoverishment of the benthic trophic resources in the upper slope sediments, this mechanism contributes to explain why also the composition of the meiofaunal assemblages in trawled sediments at 500 m in depth tends to resemble those recorded at much deeper depths along the canyon axis (i.e., at 2,000 m) (Table S5 and Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Recent investigations carried out in the north-western Mediterranean Sea have revealed that the continuous stirring, mixing, and resuspension of surface sediments by intensive and chronic trawling activities has caused changes to the present-day sediment dynamics and has permanently smoothed the seafloor morphology of the continental slope over large spatial scales (17)(18)(19). In this region, deep-sea trawled grounds are subjected to levels of sediment disturbance whose effects are larger than the changes in sediment properties associated with seasonal variability (20).…”

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confidence: 99%

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Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Pusceddu

Bianchelli

Martín

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

282

228

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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 deepsea 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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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Pusceddu

Bianchelli

Martín

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

282

228

View full text Add to dashboard Cite

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“…12). Current meter and turbidimeter data (Palanques et al, 2005b) proved that these anomalous fluxes were associated with short-lived episodes of high turbidity and high current speed that were identifiable as sediment gravity flows. These episodes were not detected at any of the other mooring sites.…”

Section: Sediment Gravity Flows In the Canyonmentioning

confidence: 99%

Composition and variability of downward particulate matter fluxes in the Palamós submarine canyon (NW Mediterranean)

Martín

Palanqués

Puig

2006

Journal of Marine Systems

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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 210 Pb 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 increases drastically at 1200 m depth, where observed particle fluxes are 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.

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“…through nepheloid layers, trawling (e.g. Palanques et al 2006) or DSWC (see below). Also, several studies point out that surface particulate organic matter in the NW Mediterranean Sea is N-rich (e.g.…”

Section: Concentration Depth Profilesmentioning

confidence: 99%

The biogeochemistry of nutrients, dissolved oxygen and chlorophyll <em>a</em> in the Catalan Sea (NW Mediterranean Sea)

Segura-Noguera

Cruzado

Blasco³

2016

Sci. Mar.

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Summary:Reference depth profiles of dissolved inorganic nutrients, dissolved oxygen and chlorophyll a are described for the Catalan Sea using quality controlled data. Phosphate, nitrate and silicate show typical nutrient profiles, with nutriclines at different depths. Maximums of nitrite, dissolved oxygen and occasionally ammonium are found within the photic zone, close to the deep chlorophyll maximum. In intermediate waters we found a minimum of dissolved oxygen coincident with maximum concentrations of phosphate and nitrate. Ammonium concentration is unexpectedly high in the mesopelagic zone, where there are still measurable nitrite concentrations. The origin of such high ammonium and nitrite concentrations remains unclear. We also identify and describe anomalous data and profiles resulting from eutrophication, western Mediterranean Deep Water formation and dense shelf water cascading. The N:P ratio in deep waters is 22.4, which indicates P limitation relative to the Redfield ratio. However, the N:P ratio above the deep chlorophyll maximum in stratified surface waters is <4 (<8 including ammonium). The depth profiles of key biogeochemical variables described in this study will be a useful reference for future studies in the Catalan Sea (NW Mediterranean Sea) in order to validate data sampled in this area, to identify anomalous processes, and to study the evolution of the ecosystem following the undergoing global change.Keywords: dissolved inorganic nutrients; dissolved oxygen; chlorophyll a; stoichiometry; P limitation; NW Mediterranean Sea; Catalan Sea Biogeoquímica de los nutrientes, oxígeno disuelto y clorofila a en el mar catalán (mar Mediterráneo noroccidental).Resumen: En este artículo se describen perfiles de profundidad de referencia para nutrientes inorgánicos disueltos, oxígeno disuelto y clorofila a en el Mar Catalán. Estos perfiles se han creado usando datos que han superado un control de calidad. Los perfiles de fosfato, nitrato y silicato son típicos de nutrientes, pero las nutriclinas se encuentran en diferentes profundidades. En la zona fótica, cerca del máximo profundo de clorofila, hay concentraciones máximas de nitrito, oxígeno disuelto y, ocasionalmente, amonio. En aguas intermedias se han detectado concentraciones mínimas de oxígeno disuelto coincidentes con concentraciones máximas de fosfato y nitrato. En la zona mesopelágica se encuentran concentraciones inesperadamente altas de amonio, así como concentraciones de nitrito por encima del límite de detección, cuyo origen se desconoce. En el presente estudio también se identifican y describen datos y perfiles anómalos resultantes de procesos de eutrofización, de formación de agua mediterránea profunda (WMDW), o de cascadas de agua densa (DSWC). La relación N:P en aguas profundas es 22.4, indicando limitación por fósforo relativo a la relación de Redfield. No obstante, la relación N:P por encima del máximo profundo de clorofila en aguas estratificadas es menor que 4 (menor que 8 si el amonio se incluye en la relación). Los perfiles de profun...

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Evidence of sediment gravity flows induced by trawling in the Palamós (Fonera) submarine canyon (northwestern Mediterranean)

Cited by 98 publications

References 32 publications

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Chronic and intensive bottom trawling impairs deep-sea biodiversity and ecosystem functioning

Composition and variability of downward particulate matter fluxes in the Palamós submarine canyon (NW Mediterranean)

The biogeochemistry of nutrients, dissolved oxygen and chlorophyll <em>a</em> in the Catalan Sea (NW Mediterranean Sea)

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