Opportunistically collected data from aerial surveys reveal spatio-temporal distribution patterns of marine debris in German waters

Bianca Unger,Helena Herr,Patricia Burkhardt-Holm,Ursula Siebert,Sacha Viquerat,Anita Gilles

doi:10.1007/s11356-020-10610-9

Abstract

Marine debris is known for its ubiquitousness and harmful effects on marine life. This study is the first analysis to provide information on the distribution of floating marine debris in German waters using aerial survey data collected between 2002 and 2016. During regular harbour porpoise monitoring flights, 191,167 km were covered and 26,512 floating debris items recorded (average encounter rate 0.1387 items/km). Debris was encountered more often in the North Sea than in the Baltic Sea (0.16 items/km; 0.08 items/km). The average encounter rate was higher in offshore waters than in coastal areas. Overlaps of marine debris distribution with ‘Special Areas of Conservation’ are a particular reason for concern. Moreover, the spring months (March–May) were identified to be the time of the year with the highest average encounter rates for marine debris. Fishing-related debris was shown to contribute up to 25% of the total number of all observed items. This study shows that opportunistically collected data on marine debris from aerial surveys are valuable for identifying distribution patterns of floating debris without additional survey effort and costs. These data can be used as baseline information to inform management schemes such as the Marine Strategy Framework Directive.

Highlights

Marine debris is a growing problem in all the world’s oceans (Barnes et al 2009; Galgani 2015; Pham et al 2014).While a large proportion of marine debris sinks to the sea floor (70% of all marine debris), 15% of marine debris is found on beaches, and 15% is floating on the surface (UNEP 2005)
This study shows that opportunistically collected data on marine debris from aerial surveys are valuable for identifying distribution patterns of floating debris without additional survey effort and costs
Marine debris was observed in varying quantities in all areas of the German North Sea and Baltic Sea

Summary

Introduction

Marine debris is a growing problem in all the world’s oceans (Barnes et al 2009; Galgani 2015; Pham et al 2014). While a large proportion of marine debris sinks to the sea floor (70% of all marine debris), 15% of marine debris is found on beaches, and 15% is floating on the surface (UNEP 2005). Winds and currents transport floating marine debris over large distances, causing local aggregations as well. Besides deteriorating the quality of marine habitats It is estimated that approximately 5 trillion plastic items with a total weight of > 250,000 t are currently floating in the world’s oceans (Eriksen et al 2014).

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