, Mendoza Amaia, Osa Juan Luis, C. Basurko Oihane, Rubio Anna, Santos María, Gago Jesús, Galgani François, Peña-Rodríguez Cristina.

Some studies identify the Bay of Biscay as a marine litter accumulation area (Galgani et al., 1995; Lebreton et al., 2012). In order to verify if this is also the case with microplastics (MPs), an overview of the research studies performed on the abundance of MPs in this marine region is presented, with the aim of addressing the general situation in the different marine compartments, highlighting limitations and knowledge gaps. Eighteen studies were located to date on waters, sediments and biota. The comparative assessment on each compartment reflects high spatial and temporal variability in the distribution of MPs, suggesting seasonal and short term influencing factors. MPs appear in all sampled compartments in a wide range of abundances, presenting in at least 50% of the samples in surface waters and sediments, with 100% occurrence in some studies. Polypropylene, polyethylene, polyester and polystyrene are found most frequently, in agreement with the main polymers reported in worldwide studies, as well as with the main polymers consumed worldwide (GESAMP, 2015). The predominance of fragments and fibres over other kind of shapes of MPs in all sampled compartments (surface water, sediments and biota) suggests that the MP source in the Bay of Biscay is more related to the decomposition of larger plastic waste rather than to direct primary inputs such as pellets or microspheres. Studies show the ubiquitous distribution of fibres in the deep marine environment in the BoB, while studies of beach sediments more frequently report MPs in the shape of fragments. The Bay of Biscay can be considered as medium MPs concentration region. However, monitoring programs are needed to compile data over time to make evaluation of trends possible. The present work highlights difficulties encountered comparing studies due to their differing methodologies. Hence, an urgent consensus is needed to standardise procedures.

View online