Benthic assemblages from a disturbed region by bottom-trawling fisheries off the SW Portuguese Margin
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1
University of Aveiro, Departamento de Biologia & CESAM, Portugal
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2
Ghent University, Department of Biology, Marine Biology Research Group, Belgium
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3
Hellenic Centre for Marine Research, Institute of Oceanography, Greece
Bottom trawlers in operation off the SW Portuguese margin target predominantly deep-sea muddy-sediment areas bellow 200m water depth. To better understand the effects caused by this practice on the deep-sea benthic habitats biodiversity, three areas of interest along a continental slope area off the SW Portuguese margin were selected, using Vessel Monitoring Systems (VMS) data and in-situ observations obtained from Remotely Operated Vehicle (ROV) video surveys. These areas included a not trawled area, the main fishing ground and an area adjacent to the main fishing ground. In addition to video surveys, which allowed characterizing mega-epibenthic assemblages, replicate sediment samples across these areas were obtained for the study of macrobenthic assemblages, in terms of total standing stocks (abundance and biomass), total respiration, composition and both taxonomic and trophic diversity. Results showed that, in addition to the habitat heterogeneity associated with the study area, trawling pressure represents an important component of variation of the observed communities. Both fishing grounds that are recurrently impacted by trawling, and the adjacent areas that may be indirectly impacted by the re-suspended sediments and sporadically affected by trawl passages, showed a depletion of both mega-epibenthic and macro-infaunal abundances, lower taxonomic and trophic richness in comparison to undisturbed sites. Moreover, a lower functional redundancy resulting from the loss of species within most feeding guilds was observed in the macrofaunal core assemblage (i.e. characteristic, dominant or frequent taxa) of the areas under trawling disturbance. These results highlight the vulnerability of the deep-sea benthic ecosystems off the SW Portuguese margin to further increases in natural and anthropogenic disturbance or their synergistic effects.
Acknowledgements
This work was supported by CESAM (UID/AMB/50017) funds, granted by Fundação para a Ciência e a Tecnologia (FCT)/MEC through national funds, and co-funded by FEDER, within the PT2020 Partnership Agreement and Compete 2020. SPR work was funded through a MARES Grant, under Erasmus Mundus programme coordinated by Ghent University (FPA 2011-0016). CFR, PE, AR and LG were supported by the FCT grants SFRH/ BPD/107805/2015, SFRH/BPD/94985/2013, SFRH/BPD/112408/2015 and SFRH/BPD/96142/2013, respectively.
Keywords:
Mega-epifauna,
macrofauna,
Upper continental slope,
trophic and structural biodiversity; disturbance,
bottom-trawling fisheries,
West Iberian Margin
Conference:
IMMR'18 | International Meeting on Marine Research 2018, Peniche, Portugal, 5 Jul - 6 Jul, 2018.
Presentation Type:
Oral Presentation
Topic:
Fisheries and Management
Citation:
Ramalho
SP,
Rodrigues
CF,
Almeida
M,
Esquete
P,
Génio
L,
Ravara
A,
Lampadariou
N,
Vanreusel
A and
Cunha
MR
(2019). Benthic assemblages from a disturbed region by bottom-trawling fisheries off the SW Portuguese Margin.
Front. Mar. Sci.
Conference Abstract:
IMMR'18 | International Meeting on Marine Research 2018.
doi: 10.3389/conf.FMARS.2018.06.00143
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Received:
28 Apr 2018;
Published Online:
07 Jan 2019.
*
Correspondence:
PhD. Sofia P Ramalho, University of Aveiro, Departamento de Biologia & CESAM, Aveiro, Portugal, Portugal, sofia.pinto.ramalho@gmail.com