Baseline study of the distribution of marine debris on soft-bottom habitats associated with trawling grounds in the northern Mediterranean

Pilar Sánchez,Montserrat Demestre,Alba Muntadas,Raquel Sáez,Silvia De Juan,Mercedes Masó

doi:10.3989/scimar03702.10a

Abstract

The present study aims to analyse the local and regional variability in the density and typology of marine debris on fishing grounds on the northern Mediterranean continental shelf, and to test relationships between marine litter and trawl fishing activity. Moreover, the colonization of plastics was examined in order to study the importance of plastics as a source of impact on marine communities and their further environmental implications. This study surveyed 11 sites, associated with trawling grounds and subjected to different levels of fishing intensity, located in four areas of the Mediterranean: one in Italy, the Central Tyrrhenian coast, one in Greece, the eastern Ionian coast, and two in Spain, the Murcian and Catalan coasts. Samples were collected during an oceanographic cruise undertaken from the 21 May to the 24 June 2009. Results showed geographical variation in the density of marine debris which ranged from 0 to 405 pieces per hectare in the surveyed areas, plastics being the dominant components. Variability within sites was higher than between areas, indicating small-scale patchiness in the distribution of the debris over the seafloor. Though the study areas were within trawling grounds, the density of debris was not significantly correlated with fishing effort. More than 30% of plastics were between 10 and 20 cm width/length, and more than 40% of the plastics were colonized by a biofilm of microorganisms, suggesting indirect effects on benthic communities.

Highlights

The noxious effect of plastic pollution on marine populations has been known since the 1960s
The list of their potential harms has increased considerably and plastic pollution is considered a real threat to marine populations and biodiversity
The accumulation of floating microplastics in convergence zones and its negative impact on marine populations through their incorporation into the food web have recently called the attention of the scientific community (Boerger et al 2010, Aloy et al 2011, Graham 2011)

Summary

Introduction

The noxious effect of plastic pollution on marine populations has been known since the 1960s. The accumulation of floating microplastics in convergence zones and its negative impact on marine populations through their incorporation into the food web have recently called the attention of the scientific community (Boerger et al 2010, Aloy et al 2011, Graham 2011). These indirect consequences are still poorly known. A recent review (Barnes et al 2009) illustrates how plastic pollution on the seabed is currently extended worldwide. Data on the distribution and abundance of plastic accumulation on the seabed are still scarce (Galgani et al 2010) and even less is known regarding the long-term dynamics of plastic in the oceans

Objectives

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Discussion

Conclusion