Recovery Signals of Rhodoliths Beds since Bottom Trawling Ban in the SCI Menorca Channel (Western Mediterranean)

Sandra Mallol,Juan-Tomás Vázquez,Sergio Ramírez-Amaro,Ulla Fernandez-Arcaya,Francesc Ordines,Gabriel Jordà,Enric Massutí,Elena Marco-Herrero,Camille Irlinger,Maria Teresa Farriols,Javier Soto-Navarro,Nuria R. de la Ballina,Natalia Martínez-Carreño,Desirée Palomino,Julio A. Díaz,David Díaz,Sergi Joher

doi:10.3390/d14010020

Sandra Mallol, Juan-Tomás Vázquez + Show 15 more

Open Access

https://doi.org/10.3390/d14010020

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Abstract

One of the objectives of the LIFE IP INTEMARES project is to assess the impact of bottom trawling on the vulnerable benthic habitats of the circalittoral bottoms of the Menorca Channel (western Mediterranean), designated a Site of Community Importance (SCI) within the Natura 2000 network. The present study compares the epibenthic communities of four areas, subjected to different bottom trawl fishing intensity levels. The assignment of fishing effort levels was based on the fishing effort distribution in the area calculated from Vessel Monitoring System (VMS) data and the existence of two Fishing Protected Zones in the Menorca Channel. Biological samples were collected from 39 beam trawl stations, sampled during a scientific survey on April 2019. We compare the diversity, composition, and density of the epibenthic flora and fauna, together with the rhodoliths coverage and the morphology of the main species of rhodoliths of four areas subjected to different levels of bottom trawl fishing effort, including one that has never been impacted by trawling. Our results have shown negative impacts of bottom trawling on rhodoliths beds and the first signals of their recovery in areas recently closed to this fishery, which indicate that this is an effective measure for the conservation of this habitat of special interest and must be included in the management plan required to declare the Menorca Channel as a Special Area of Conservation.

Highlights

Rhodoliths beds are bottoms characterized by the accumulation of calcareous red algae, mainly belonging to the orders Corallinales and Hapalidiales, some Peyssonneliales can form rhodoliths [1]
Sediments showed a higher proportion of gravel in Medium effort history and High effort areas than in Non-impacted and Low effort history areas, while the proportion of sand was lower in Medium effort history and High effort areas than in Non-impacted and
The results have shown clear differences in the composition and diversity of epibenthic communities, as well as in the size and morphology of the rhodolith species analyzed, due to the impact of bottom trawl fishing activity

Summary

Introduction

Rhodoliths beds are bottoms characterized by the accumulation of calcareous red algae, mainly belonging to the orders Corallinales and Hapalidiales, some Peyssonneliales can form rhodoliths [1]. Rhodoliths prefer sedimentary bottoms subject to moderate water currents, allowing a rolling movement that eases their growth, prevents burial by sediment, and hinders overgrowth by other algae [7,8,9]. Rhodoliths-forming species are considered bioengineers [2,10,11,12], as they increase the structural complexity of the sedimentary bottoms, creating habitats that provide the refuge needed for a wide variety of marine species during key vital stages such as settlement and nursing [12,13,14,15,16]. Different impacts, such as rhodoliths extraction, fishing, aquaculture, pollution, invasive species, and the combined pressures of ocean warming and acidification, endanger this habitat and its important biological and physico-chemical role [2,10,16,18,19]

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