Impacts of Discarded Plastic Bags on Marine Assemblages and Ecosystem Functioning

The accumulation of plastic debris is a global environmental problem due to its durability, persistence, and abundance. Although effects of plastic debris on individual marine organisms, particularly mammals and birds, have been extensively documented (e.g., entanglement and choking), very little is known about effects on assemblages and consequences for ecosystem functioning. In Europe, around 40% of the plastic items produced are utilized as single-use packaging, which rapidly accumulate in waste management facilities and as litter in the environment. A range of biodegradable plastics have been developed with the aspiration of reducing the persistence of litter; however, their impacts on marine assemblages or ecosystem functioning have never been evaluated. A field experiment was conducted to assess the impact of conventional and biodegradable plastic carrier bags as litter on benthic macro- and meio-faunal assemblages and biogeochemical processes (primary productivity, redox condition, organic matter content, and pore-water nutrients) on an intertidal shore near Dublin, Ireland. After 9 weeks, the presence of either type of bag created anoxic conditions within the sediment along with reduced primary productivity and organic matter and significantly lower abundances of infaunal invertebrates. This indicates that both conventional and biodegradable bags can rapidly alter marine assemblages and the ecosystem services they provide

River inputs of nitrate and chlorophyll.

<p>River inputs of nitrate and chlorophyll.</p

Observed and modeled (in black) sea surface temperature (a, c and e) and chlorophyll (b, d and f) at latitude 42°N and longitudes 9°W, 9.75°W and 10.5°W (locations indicated as triangles in Figure 2.

<p>The satellite observations are distributed by OSISAF and by IFREMER. Note the different vertical scales for chlorophyll. Each data points is the average of the data inside a circle of radius 7 km. Error bars are the corresponding standard deviations.</p

Model bias of sea surface temperature (a) and chlorophyll (b) for the period 10^th June 2011 to 10^th October 2011.

<p>Model bias of sea surface temperature (a) and chlorophyll (b) for the period 10^th June 2011 to 10^th October 2011.</p

Study region with nested grids configuration of the atmospheric model (ATM) and ocean model (OCEAN-0 and target domain OCEAN-1).

<p>Study region with nested grids configuration of the atmospheric model (ATM) and ocean model (OCEAN-0 and target domain OCEAN-1).</p

Sea surface temperature from model (upper panel) and from satellite observations provided by OSISAF (lower panel, processed by Meteo-France/CMS-Lannion in the framework of the OSISAF project).

<p>Snapshots between 13^th and 26^th July 2011 are depicted, illustrating one episode of upwelling intensification and coastal bloom (next Figure).</p

Observed and modeled surface currents at three locations along the latitude 42°N at the longitudes 9°W (a and b), 9.75°W (c and d) and 10.5°W (e and f).

<p>These locations are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037343#pone-0037343-g002" target="_blank">Figure 2</a> as triangles.</p

Parameter values of the NPZD model.

<p>Parameter values of the NPZD model.</p

Same as previous figure but showing the chlorophyll coastal bloom.

<p>Chlorophyll observations are provided by IFREMER and obtained from OC5 optimised interpolation of MODIS, SeaWiFS and MERIS observations.</p

Same as <b>Figure 7</b> but for the latitude 38

<p>°<b>N.</b></p