Modelling the fate of marine debris along a complex shoreline: Lessons from the Great Barrier Reef

Abstract

The accumulation of floating anthropogenic debris in marine and coastal areas has environmental, economic, aesthetic, and human health impacts. Until now, modelling the transport of such debris has largely been restricted to the large-scales of open seas. We used oceanographic modelling to identify potential sites of debris accumulation along a rugged coastline with headlands, islands, rocky coasts and beaches. Our study site was the Great Barrier Reef World Heritage Area that has an emerging problem with debris accumulation. We found that the classical techniques of modelling the transport of floating debris models are only moderately successful due to a number of unknowns or assumptions, such as the value of the wind drift coefficient, the variability of the oceanic forcing and of the wind, the resuspension of some floating debris by waves, and the poorly known relative contribution of floating debris from urban rivers and commercial and recreational shipping. Nevertheless the model was successful in reproducing a number of observations such as the existence of hot spots of accumulation. The orientation of beaches to the prevailing wind direction affected the accumulation rate of debris. The wind drift coefficient and the exact timing of the release of the debris at sea affected little the movement of debris originating from rivers but it affected measurably that of debris originating from ships. It was thus possible to produce local hotspot maps for floating debris, especially those originating from rivers. Such modelling can be used to inform local management decisions, and it also identifies likely priority research areas to more reliably predict the trajectory and landing points of floating debris.

Changes in the Floating Plastic Pollution of the Mediterranean Sea in Relation to the Distance to Land

“…Plastic fragments’s abundances (lower graph) includes measurements made during this study in the western Mediterranean (green circles) and data reported by Lucia et al (blue circles; [17]) and Cózar et al (red circles; [15]).…”

Microplastic ingestion ubiquitous in marine turtles

“…Firstly, the presence of synthetic particles in marine turtles could be due to environmental exposure to areas of contaminated sea water or sediments. Numerous studies have now identified microplastics in seawater worldwide creating potential exposure during foraging, nesting and migration (Critchell et al, ; Gago et al, ; van Sebille et al, ). Microplastics have also been shown to move from source to sediments (Gago et al, ), with low‐density plastics eventually reaching the seafloor though density‐modification, as a result of biofouling or integration into zooplankton faecal matter (Alomar, Estarellas, & Deudero, ; Andrady, ; Cole et al, ; Coppock, Cole, Lindeque, Queirós, & Galloway, ; Cózar et al, ; Van Cauwenberghe, Devriese, Galgani, Robbens, & Janssen, ).…”

“…Firstly, the presence of synthetic particles in marine turtles could be due to environmental exposure to areas of contaminated sea water or sediments. Numerous studies have now identified microplastics in seawater worldwide creating potential exposure during foraging, nesting and migration (Critchell et al, 2015;Gago et al, 2018;van Sebille et al, 2015).…”

Combining Litter Observations with a Regional Ocean Model to Identify Sources and Sinks of Floating Debris in a Semi-enclosed Basin: The Adriatic Sea

“…Identifying sources and sinks of AMD can assist resource managers maximize the effectiveness of prevention and response efforts by providing scientific support to the implementation of public policies. While progress has been made, most relevant studies either relied on observations of beached AMD (Yoon et al, 2010;Kako et al, 2011Kako et al, , 2014Neumann et al, 2014), made assumptions about the amount of AMD as well as its temporal and/or spatial distributions (Lebreton et al, 2012;Critchell et al, 2015;Mansui et al, 2015;Liubartseva et al, 2016), or used coarse resolution velocity data and/or idealized surface currents (Aliani and Molcard, 2003;Maximenko et al, 2012;van Sebille et al, 2012;Reisser et al, 2013;Isobe et al, 2014). Such studies have identified the physical processes relevant to the transport and accumulation of debris, however, the efficacy of models in aiding management efforts depends strongly on the assumptions applied in the particle tracking scheme (Critchell and Lambrechts, 2016) as well as the resolution and accuracy of the underlying velocity field (Putman and He, 2013).…”