COVID-19 Pandemic Lockdown: An Excellent Opportunity to Study the Effects of Trawling Disturbance on Macrobenthic Fauna in the Shallow Waters of the Gulf of Gabès (Tunisia, Central Mediterranean Sea).

Nawfel Mosbahi,Jean-Claude Dauvin,Jean-Philippe Pezy,Lassad Neifar

doi:10.3390/ijerph19031282

Abstract

This study describes for the first time in the central Mediterranean Sea the effects of bottom trawling on macrobenthic fauna in tidal channels of the Kneiss Islands in the Gulf of Gabès, Tunisia. Following a BACI protocol, two control stations (protected by artificial reefs) and two trawled stations (impacted stations) were sampled during a period with the absence of bottom trawling activity (the COVID-19 pandemic lockdown period from March to May 2020) and during a trawled period. Although bottom trawling had no impact on sediment composition, this anthropogenic activity reduced the concentration of dissolved oxygen and had a noticeable effect on water column turbidity. The absence of trawling led to a significant increase in biomass, number of species, and abundance of total macrofauna. This illustrated the negative effect of trawling activity in shallow waters and the high resilience of macrobenthic communities of the tidal ecosystem of the Kneiss Islands. In the future, it would be very important to control the use of this destructive fishing gear due to its negative impact on the marine habitat and macrofauna, which represents essential prey for fishes and birds living in this protected area.

Highlights

Bottom trawling is one of the most harmful anthropogenic activities on both shallow and deep marine ecosystems [1,2,3]
The organic matter content varied between 2.6% (C2)
The present study shows the negative effects of bottom trawling on macrobenthic fauna in the tidal channels of the Kneiss Islands

Summary

Introduction

Bottom trawling is one of the most harmful anthropogenic activities on both shallow and deep marine ecosystems [1,2,3]. Bottom trawling provokes sediment re-suspension; decreases macrofaunal bioturbation processes; and removes, injures, or kills a wide range of sedentary organisms It induces changes in the population demography and can have dire consequences on ecosystem structures and functions [7,8,9,10]. The Gulf of Gabès, located in the central part of the Mediterranean, covers the secondwidest continental shelf area (35,900 km2 ) and is characterized by unique geomorphological, climatic, and oceanographic conditions. This gulf has an extensive network of tidal channels and very gentle slopes [11]. The Gulf of Gabès is an important nursery for several fish species and represents one of the main target areas for fishing activities in Tunisia; it is among the most highly productive zones in the

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