Beach wrack on Baltic and Mediterranean Sea Beaches: litter pollution and management perspectives

Abstract

Beach wrack can accumulate in large quantities on beaches and is often regarded as a nuisance by beach managers, which is removed for the sake of tourists. The litter entangled in beach wrack can prevent further use of this natural resource. However, not much is known about the litter quantities in beach wrack nor their input paths. We applied an easy-to-use method for beach wrack monitoring in two case studies, in the southern Mediterranean Sea and the eastern German Baltic Sea. Our objective was to investigate whether litter found in beach wrack provides an indication for the input path “sea to beach” and whether there is a correlation between beach wrack and litter quantities, allowing an extrapolation of litter quantities to longer stretches of coastline based on beach wrack cover. The results of 14 surveys in Germany and 6 surveys in North Africa do not provide sufficient evidence for the input path “sea to beach” for litter in beach wrack nor for a correlation between beach wrack and litter quantities. However, we show that litter quantities in beach wrack at the waterline can be 3–13 times higher than what is found on bare sand and that old, scattered beach wrack may entrap 181 times more litter, evidencing that it serves as a sink of litter on beaches. We recommend further large-scale studies, targeting freshly deposited wrack, to gain more information on beach wrack litter quantities and input paths, and to support better decision-making on beach wrack management.