title: Spatial variability of soft-bottom macrobenthic communities in northern Sicily (Western Mediterranean): Contrasting trawled vs. untrawled areas.
abstract: This study examines the impact of bottom trawl fishing on the macrobenthic communities inhabiting the coastal terrigenous mud off the northern coast of Sicily (Western Mediterranean). Two intensely trawled gulfs were compared with two gulfs from which trawling has been excluded for 15 years. The results show a significant effect of trawling on the faunal assemblage and when comparing the mean biomass and the whole isotopic composition of the benthic communities. A similar pattern, although not significant, was found for total abundance, biomass, production/biomass ratio and diversity. Higher abundance and lower biomass were found in the untrawled areas, attributable to the presence of more numerous yet smaller individuals, possibly a consequence of more abundant larger predators that are not removed by trawling, and consequent higher predatory pressure on the benthic macrofauna. The SIMPER analysis evidenced a dominance of burrowing deposit feeding worms (Paraonidae and Cossuridae) in trawled areas, as a result of increased mechanical alteration and hence more organic matter available as food. In contrast, the response to trawling as drawn by the use of trophic markers (i.e., stable isotopes) was less clear. While δ15N of benthic taxa did not vary significantly between untrawled and trawled areas, δ13C was higher in trawled areas possibly due to high sediment resuspension and consequent intense microbial activity. Mixing models confirmed higher reliance to a detritus-based food web for benthic organisms in the trawled areas. Standard Ellipse Areas (SEAc) as a measure of community niche width were slightly larger in trawled areas, likely due to higher generalism triggered by alteration/removal of the original benthic community.
authors: Centre d'Estudis Avançats de Blanes (CEAB-CSIC) Carrer d'acces a la Cala Sant Francesc 14, 17300, Blanes (Girona), Catalunya, Spain; Marine Invertebrate Phylogenetics Lab., Scripps Institution of Oceanography, 8750 Biological Grade Hubbs Hall, La Jolla, CA, 92037, USA.
authors: C
authors: C
authors: Romano
authors: Marine Environment Research Centre ENEA - Santa Teresa Pozzuolo di Lerici, 19100, SP, Italy. Electronic address: emanuela.fanelli@enea.it.
authors: E
authors: E
authors: Fanelli
authors: CNR-IAMC, Sede di Castellammare del Golfo, via Giovanni da Verrazzano 17, 91014 Castellammare del Golfo, Italy.
authors: G
authors: G
authors: D'Anna
authors: CNR-IAMC, Sede di Castellammare del Golfo, via Giovanni da Verrazzano 17, 91014 Castellammare del Golfo, Italy.
authors: C
authors: C
authors: Pipitone
authors: Dipartimento di Scienze della Terra e del Mare, CoNISMa, Via Archirafi 18, 90123 Palermo, Italy.
authors: S
authors: S
authors: Vizzini
authors: Dipartimento di Scienze della Terra e del Mare, CoNISMa, Via Archirafi 18, 90123 Palermo, Italy.
authors: A
authors: A
authors: Mazzola
authors: CNR-IAMC, Sede di Castellammare del Golfo, via Giovanni da Verrazzano 17, 91014 Castellammare del Golfo, Italy.
authors: F
authors: F
authors: Badalamenti
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000502:physiology*; D044822:Biodiversity; D017753:Ecosystem; D004784:Environmental Monitoring; D005398:Fisheries / Q000706:statistics & numerical data*; D007448:Invertebrates / Q000502:physiology*; D012802:Sicily
keywords: Benthic communities; Continental shelf; Fishery exclusion zones; Spatial closures; Stable isotope analysis; Trawling impact