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Meeuwen
Image: ©Dutch Fishermen’s Association

Effects on the ecosystem

Bottom trawls impact the structure and functioning of the benthic ecosystem (Jennings and Kaiser, 1998). The impact is related to the mechanical effects of the gear components that either sweep or penetrate into the seafloor (Eigaard et al. 2016). Bottom trawls may homogenise the texture of the seafloor, disturb the sorting of the sediments and bring sediment into resuspension in the wake of the gear (O’Neill et al., 2016). Mechanical disturbance will also kill benthic invertebrates and may destroy biogenic structures (Kaiser et al., 2006). In addition to the mechanical impact, electrical stimuli may affect the ecological functioning of the benthos and may influence chemistry of the seabed.

Hypothesis on chemical reactions

It is hypothesised that the electrical field may affect chemical reactions which might release pollutants that are bound to sediment particles (Soetaert et al., 2015). To our knowledge, no studies have addressed this question.

Unknown effects on functioning of benthic invertebrates

It is unknown how chronic sub-lethal exposure will affect the functioning of the benthic invertebrates. Although the few experiments with benthic invertebrates seems to suggest that the exposed organisms resumed their normal behaviour soon after the pulse treatment, further studies are required.

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