PAME Work Plan

Plastic debris is a widespread contaminant, prevalent in aquatic ecosystems across the globe. Zooplankton readily ingest microscopic plastic (microplastic, < 1 mm), which are later egested within their faecal pellets. These pellets are a source of food for marine organisms, and contribute to the oceanic vertical flux of particulate organic matter as part of the biological pump. The effects of microplastics on faecal pellet properties are currently unknown. Here we test the hypotheses that (1) faecal pellets are a vector for transport of microplastics, (2) polystyrene microplastics can alter the properties and sinking rates of zooplankton egests and, (3) faecal pellets can facilitate the transfer of plastics to coprophagous biota. Following exposure to 20.6 μm polystyrene microplastics (1000 microplastics mL−1) and natural prey (∼1650 algae mL−1) the copepod Calanus helgolandicus egested faecal pellets with significantly (P < 0.001) reduced densities, a 2.25-fold reduction in sinking rates, and a higher propensity for fragmentation. We further show that microplastics, encapsulated within egests of the copepod Centropages typicus, could be transferred to C. helgolandicus via coprophagy. Our results support the proposal that sinking faecal matter represents a mechanism by which floating plastics can be vertically transported away from surface waters.

Microscopic plastic debris, termed “micro-plastics”, are of increasing environmental concern. Recent studies have demonstrated that a range of zooplankton, including copepods, can ingest microplastics. Copepods are a globally abundant class of zooplankton that form a key trophic link between primary producers and higher trophic marine organisms. Here we demonstrate that ingestion of micro- plastics can significantly alter the feeding capacity of the pelagic copepod Calanus helgolandicus. Exposed to 20 μm polystyrene beads (75 microplastics mL−1) and cultured algae ([250 μg C L−1) for 24 h, C. helgolandicus ingested 11% fewer algal cells (P = 0.33) and 40% less carbon biomass (P < 0.01). There was a net downward shift in the mean size of algal prey consumed (P < 0.001), with a 3.6 fold increase in ingestion rate for the smallest size class of algal prey (11.6−12.6 μm), suggestive of postcapture or postingestion rejection. Prolonged exposure to polystyrene microplastics significantly decreased reproductive output, but there were no significant differences in egg production rates, respiration or survival. We constructed a conceptual energetic (carbon) budget showing that microplastic-exposed copepods suffer energetic depletion over time. We conclude that microplastics impede feeding in copepods, which over time could lead to sustained reductions in ingested carbon biomass.

Small plastic detritus, termed “microplastics”, are a widespread and ubiquitous contaminant of marine ecosystems across the globe. Ingestion of microplastics by marine biota, including mussels, worms, fish, and seabirds, has been widely reported, but despite their vital ecological role in marine food-webs, the impact of microplastics on zooplankton remains under-researched. Here, we show that microplastics are ingested by, and may impact upon, zooplankton. We used bioimaging techniques to document ingestion, egestion, and adherence of microplastics in a range of zooplankton common to the northeast Atlantic, and employed feeding rate studies to determine the impact of plastic detritus on algal ingestion rates in copepods. Using fluorescence and coherent anti-Stokes Raman scattering (CARS) microscopy we identified that thirteen zooplankton taxa had the capacity to ingest 1.7−30.6 μm polystyrene beads, with uptake varying by taxa, life-stage and bead-size. Post-ingestion, copepods egested faecal pellets laden with microplastics. We further observed microplastics adhered to the external carapace and appendages of exposed zooplankton. Exposure of the copepod Centropages typicus to natural assemblages of algae with and without microplastics showed that 7.3 μm microplastics (>4000 mL−1) significantly decreased algal feeding. Our findings imply that marine microplastic debris can negatively impact upon zooplankton function and health.

The distribution, abundance, and characteristics of neuston plastic in the North Pacific, Bering Sea, and Japan Sea were studied during the 4-yearperiod 1985-88at 203 neuston stations encompassing ca. 91,000m2 of sampling. The highest total density of neuston plastic was 316,800pieces/km2 at lat. 35"59'N, long. 152"OO'E in Transitional Water east of Japan. The highest total concentration of neuston plastic was 3,491.8 g/km2 atlat.40"00'N,long.171'30'E neartheSubarcticFrontinthe central North Pacific. Main types of neuston plastic were miscellaneous line fragments (21.7% of all stations), Styrofoam (12.8%), polypropylene line fragments (7.4%), miscellaneous or unidentified plastic (7.4%), and raw pellets (5.9%). Plastic fragments were recorded at 52.2% of all stations and at 88.3% of those stations with plastic. The highest densities (number per square kilometer) and concentrations (gram per square kilometer) of neuston plastic occurred in Japan Sea/nearshore Japan Water, in Transitional Water, and in Subtropical Water. Densities of neuston plastic in Subarctic Water and Bering Sea Water were low. Heterogeneous geographic input and currents and winds are important in distributing and concentrating neuston plastic. Microscale convergences appear to be important mechanisms that locally concentrate neuston plastic, increasing the probability of its entering food chains.

Sources, pathways and reservoirs of microplastics, plastic particles smaller than 5 mm, remain poorly documented in an urban context. While some studies pointed out wastewater treatment plants as a potential pathway of microplastics, none have focused on the atmospheric compartment. In this work, the atmospheric fallout of microplastics was investigated in two different urban and sub-urban sites. Microplastics were collected continu- ously with a stainless steel funnel. Samples were then filtered and observed with a stereomicroscope. Fibers accounted for almost all the microplastics collected. An atmospheric fallout between 2 and 355 particles/m2/ day was highlighted. Registered fluxes were systematically higher at the urban than at the sub-urban site. Chemical characterization allowed to estimate at 29% the proportion of these fibers being all synthetic (made with petrochemicals), or a mixture of natural and synthetic material. Extrapolation using weight and volume estimates of the collected fibers, allowed a rough estimation showing that between 3 and 10 tons of fibers are deposited by atmospheric fallout at the scale of the Parisian agglomeration every year (2500 km2). These results could serve the scientific community working on the different sources of microplastic in both continental and marine environments.

Sources, pathways and reservoirs of microplastics, plastic particles smaller than 5 mm, remain poorly document- ed in an urban context. While some studies pointed out wastewater treatment plants as a potential pathway of microplastics, none have focused on the atmospheric compartment. In this work, the atmospheric fallout of microplastics was investigated in two different urban and sub-urban sites. Microplastics were collected continu- ously with a stainless steel funnel. Samples were then filtered and observed with a stereomicroscope. Fibers accounted for almost all the microplastics collected. An atmospheric fallout between 2 and 355 particles/m2/ day was highlighted. Registered fluxes were systematically higher at the urban than at the sub-urban site. Chem- ical characterization allowed to estimate at 29% the proportion of these fibers being all synthetic (made with pet- rochemicals), or a mixture of natural and synthetic material. Extrapolation using weight and volume estimates of the collected fibers, allowed a rough estimation showing that between 3 and 10 tons of fibers are deposited by atmospheric fallout at the scale of the Parisian agglomeration every year (2500 km2). These results could serve the scientific community working on the different sources of microplastic in both continental and marine environments.

Marine microscopic plastic (microplastic) debris is a modern societal issue, illustrating the challenge of balancing the con­ venience of plastic in daily life with the prospect of causing ecological harm by careless disposal. Here we develop the con­ cept of microplastic as a complex, dynamic mixture of polymers and additives, to which organic material and contaminants can successively bind to form an ‘ecocorona’, increasing the density and surface charge of particles and changing their bio­ availability and toxicity. Chronic exposure to microplastic is rarely lethal, but can adversely affect individual animals, reducing feeding and depleting energy stores, with knock-on effects for fecundity and growth. We explore the extent to which ecological processes could be impacted, including altered behaviours, bioturbation and impacts on carbon flux to the deep ocean. We discuss how microplastic compares with other anthropogenic pollutants in terms of ecological risk, and consider the role of science and society in tackling this global issue in the future.

The role of microplastic particles in the cycling and bioaccumulation of persistent organic pollutants (POPs) is discussed. Five common concepts, sometimes misconceptions, about the role of microplastics are reviewed. While there is ample evidence that microplastics accumulate high concentrations of POPs, this does not result in microplastics being important for the global dispersion of POPs. Similarly, there is scant evidence that microplastics are an important transfer vector of POPs into animals, but possibly for plastic additives (flame retardants). Last, listing microplastics as POPs could help reduce their environmental impact.