Impact of bottom trawling on water turbidity and muddy sediment of an unfished continental shelf
TLDR
In this article, two experiments were carried out to study the effects of trawling in the muddy prodeltaic deposit of the Llobregat River in the northwestern Mediterranean.Abstract:
Two experiments were carried out to study the effects of trawling in the muddy prodeltaic deposit of the Llobregat River in the northwestern Mediterranean. Trawling was conducted in two experimental lines, and bottom morphology, sediment texture, and water turbidity were analyzed before trawling and at different time intervals afterward. The tracks of the trawl gears were still observed in sonographs of the bottom 1 yr after the first experiment. The vertical grain size distribution of bottom deposits indicated that the thickness of the sediment removed by the net between the gears was about 2–3 cm on average, though the erosion produced by the gears was deeper. Resuspended aggregates with a high silt content settled during the first hour after trawling, generating a temporary increase in the silt content of the surface sediment. One day after trawling, the surface sediment was mixed and already had a similar grain size distribution to that before trawling. After the beginning of trawling, water turbidity increased first near the bottom for a few hours and later also at shallower levels of the water column within a period of 2–5 d after trawling. At the end of the experiment, about 10% of the sediment affected by trawling was diffused in the water column and the remaining 90% had settled on the bottom. Average turbidity in the water column increased by a factor of up to three for 4–5 d after trawling. This experiment shows that intense and continued trawling on continental shelves has a noticeable effect on water turbidity, which must be considered in addition to natural processes.read more
Citations
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Long-term decline of the populations of Fucales (Cystoseira spp. and Sargassum spp.) in the Albères coast (France, North-western Mediterranean).
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References
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Journal ArticleDOI
The impacts of mobile fishing gear on seafloor habitats in the gulf of Maine (Northwest Atlantic): Implications for conservation of fish populations
Peter J. Auster,Richard J. Malatesta,Richard W. Langton,Les Watting,Page C. Valentine,Carol Lee S. Donaldson,Elizabeth W. Langton,Andrew N. Shepard,War G. Babb +8 more
TL;DR: In this paper, the physical structure of benthic habitats was reduced by direct removal of biogenic (e.g., sponges, hydrozoans, bryozoans, amphipod tubes, holothurians, shell aggregates) and sedimentary (i.e., sand waves, depressions).
Journal ArticleDOI
The effects of beam-trawl disturbance on infaunal communities in different habitats
Michel J. Kaiser,B. E. Spencer +1 more
TL;DR: This study investigated its local impact on an infaunal community in the north-eastern Irish Sea and found no difference between fished and unfished areas, which suggests that the effects of fishing disturbance are consistent between replicate samples.
The effects of fishing on non-target species and habitats: biological, conservation and socio-economic issues
Michel J. Kaiser,S.J. De Groot +1 more
TL;DR: In this article, the authors investigated the impact of trawling on benthic habitats and fishes in the North Sea and found that trawlers were responsible for the regression of Posidonia oceanica meadows in the Mediterranean Sea (G.C. Ardizzone, P.T. Tucci, A.S. van Santbrink).
Journal ArticleDOI
Effects of physical trawling disturbance in a previously unfished sheltered Scottish sea loch
TL;DR: The effects of trawling disturbance on a benthic community were investigated with a manipulative field experiment in a fine muddy habitat that has been closed to fishing for over 25 yr and physical effects were identifiable immediately after disturbance, but were almost indistinguishable after 18 mo of recovery.
Journal ArticleDOI
The effect of commercial trawling on sediment resuspension and transport over the Middle Atlantic Bight continental shelf
TL;DR: In this article, time-averaged concentrations of sediment resuspended by trawls from various areas of the Middle Atlantic Bight continental shelf were estimated using a simple mathematical model and National Marine Fisheries Service records of commercial trawling activity.
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