Júlia Reisser - Academia.edu (original) (raw)

Júlia Reisser

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Papers by Júlia Reisser

Millimetre-sized plastics are numerically abundant and widespread across the world’s ocean surfac... more Millimetre-sized plastics are numerically abundant and widespread across the world’s ocean surface. These
buoyant macroscopic particles can be mixed within the up-
per water column by turbulent transport. Models indicate that
the largest decrease in their concentration occurs within the
first few metres of water, where in situ observations are very
scarce. In order to investigate the depth profile and physical
properties of buoyant plastic debris, we used a new type of
multi-level trawl at 12 sites within the North Atlantic sub-
tropical gyre to sample from the air–seawater interface to a
depth of 5 m, at 0.5 m intervals. Our results show that plastic
concentrations drop exponentially with water depth, and decay rates decrease with increasing Beaufort number. Furthermore, smaller pieces presented lower rise velocities and were
more susceptible to vertical transport. This resulted in higher depth decays of plastic mass concentration (milligrams m−3) than numerical concentration (pieces m−3 ). Further multi-level sampling of plastics will improve our ability to predict at-sea plastic load, size distribution, drifting pattern, and impact on marine species and habitats.

Marine microplastics (<5 mm in length) can contain high loads of additives and adsorbed pollutant... more Marine microplastics (<5 mm in length) can contain high loads of additives and adsorbed pollutants, and may be a threat to marine food webs due to their ingestion by organisms at the base of the food chain (http://www.unep.org/yearbook/). Most of our knowledge on plastic ingestion by zooplankton has been obtained through experiments assuming that plastic parti- cles have to be smaller than the organism’s feeding apparatus for this type of interac- tion to occur (Cole et al., 2013). However, we propose that this is not a rule.

Plastic pollution is ubiquitous throughout the marine environment, yet estimates of the global ab... more Plastic pollution is ubiquitous throughout the marine environment, yet estimates of the global abundance and weight of floating plastics have lacked data, particularly from the Southern Hemisphere and remote regions. Here we report an estimate of the total number of plastic particles and their weight floating in the world’s oceans from 24 expeditions (2007–2013) across all five sub-tropical gyres, costal Australia, Bay of Bengal and the Mediterranean Sea conducting surface net tows (N5680) and visual survey transects of large plastic debris (N5891). Using an oceanographic model of floating debris dispersal calibrated by our data, and correcting for wind-driven vertical mixing, we estimate a minimum of 5.25 trillion particles weighing 268,940 tons. When comparing between four size classes, two microplastic ,4.75 mm and meso- and macroplastic .4.75 mm, a tremendous loss of microplastics is observed from the sea surface compared to expected rates of fragmentation, suggesting there are mechanisms at play that remove ,4.75 mm plastic particles from the ocean surface.