Relative Abundance of Floating Plastic Debris and Neuston in the Eastern North Pacific Ocean

Despite an increasing research conducted on ocean plastic pollution over the last decade, there are still large knowledge gaps in our current understanding of how floating plastic debris accumulating in subtropical oceanic gyres may harm the surface-associated pelagic community known as neuston. Removing floating plastic debris from the surface ocean can minimize potentially adverse effects of plastic pollution on the neuston, as well as prevent the formation of large quantities of secondary micro- and nanoplastics. However, due to the scarcity of observational data from remote and difficult to access offshore waters, neuston dynamics in subtropical oceanic gyres and thus the potential impacts of plastic pollution as well as of cleanup activities on the neuston remain uncertain. Here, we provide rare observational data of the relative distribution of floating plastic debris (0.05–5 cm in size) and members of the neuston in the eastern North Pacific Ocean. Our results reveal that the dominant neustonic species co-occurring with high concentrations of floating plastic debris in the North Pacific Garbage Patch (NPGP) such as Porpita porpita, Halobates spp., pteropods, isopods, heteropods, and crabs depict either a low atmospheric drag due to physical attributes or a potential plastic-associated fitness benefit such as increased surface area for oviposition and structure for habitat. We further observe relatively higher plastic to organism ratios inside the NPGP for most target species compared to waters outside the NPGP. The findings presented here provide a first observational baseline to develop ecological models that can help evaluate the long-term risks of plastic pollution and of offshore cleanup activities for neuston in the eastern North Pacific Ocean. We further suggest that offshore mitigation strategies aiming at removing floating plastic debris from the ocean surface need to evaluate both, the direct impact of neuston bycatch during plastic removal on neuston population dynamics, as well as the potential benefits of reducing the negative effects of plastic pollution on the neuston.

Characterizing plastic debris accumulating in the North Pacific Garbage Patch

<p>Citizen science programs and tracking applications have been used in the collection of data on plastic debris in marine environments to determine its composition and sources. These programs, however, are mostly focused on debris collected from beach cleanups and coastal environments. Large plastic debris currently afloat at sea, which is a significant contributor to marine plastic pollution and a major source of beach litter, is less well-characterized.</p><p>Transported by currents, wind and waves, positively buoyant plastic objects eventually accumulate at the sea surface of subtropical oceanic gyres, forming the so-called ocean garbage patches. It is important to know where the debris that persists in the offshore gyres is entering the ocean, where it is produced and what practices (commercial, cultural, industrial) are contributing to the accumulation of these debris into the ocean garbage patches. This information coupled to data on how long and well the plastics persevere at the sea surface is necessary for creating effective and efficient mitigation strategies.</p><p>Here we provide a comprehensive assessment of plastic debris afloat in the North Pacific Garbage Patch (NPGP). Offshore debris collected by The Ocean Cleanup’s System 001b from the NPGP in 2019 was analyzed using the Litter-ID method, which applies an adapted and expended version of the OSPAR guideline for monitoring beach litter. Our results reveal new insights into the composition, origin and age of plastic debris accumulating at the ocean surface in the NPGP. The standardized methodology applied here further enables a first thorough comparison of plastic debris accumulating in offshore waters and coastal environments.</p>

Paddle surfing for science on microplastic pollution: a successful citizen science initiative

<p>Research on microplastics has rapidly expanded in recent years and has led to the discovery of vast amounts of microplastics floating offshore in all main oceanic gyres and including the Mediterranean Sea. However, there is a lack of information from a few meters from the coastline where the largest plastic mass flux is suspected to occur. The reason behind is the general use of manta trawls towed by boats or research vessels to obtain samples, which hinders nearshore sampling. We have designed a manta trawl to collect samples in the nearshore from any type of recreational sports floating gear like kayaks, sailboats, rowing boats, windsurf boards and others. Data generated is comparable to that obtained with traditional scientific equipment towed from boats. During one year, starting from October 2020, 12 social, environmental and sports associations along the NW Mediterranean coast are acquiring scientific samples in the nearshore within the frame of two citizen science monitoring projects lead by the Spanish delegation of the non-governmental organization Surfrider Foundation Europe and the University of Barcelona. The projects represent a paradigm shift in microplastic research, allowing to fill the gap in knowledge of this transition coastal area, and actively involving citizens in the generation of new monitoring data (https://surfingforscience.org/).</p><p>Our results reveal that densities of floating plastics in the nearshore along the NW Mediterranean coast are on average similar to those found offshore. However, we observe high variability due to meteorological and oceanographic conditions (i.e. the occurrence of eastern storms). We also observe that whereas floating microplastics dominate offshore, greater proportions of mesoplastics and macroplastics dominate at the nearshore waters, especially in between the breakwaters in Barcelona city. Indeed, the breakwaters, that protect Barcelona beaches against wave action and coastal erosion, behave as plastic traps. This is an indication of the importance of the nearshore as a source of plastic fragments to the open sea and calls for increased research in this area.</p>

First evidence of plastic fallout from the Great Pacific Garbage Patch

<p>Increasing amounts of plastic debris in the ocean is a global environmental concern. Each year, several million tons of plastic waste enter the ocean from coastal environments. Transported by currents, wind and waves, positively buoyant plastic objects eventually accumulate at the sea surface of subtropical oceanic gyres, forming the so-called ocean garbage patches. To date, the fate of floating plastic debris ‘trapped’ in the oceanic gyres remains largely unknown. To more accurately assess the persistence of floating plastics accumulating in offshore areas, a better understanding of the plastic inputs and outputs into and from ocean garbage patches is crucial. An important component of this mass balance currently missing is the vertical plastic flux from the sea surface of subtropical waters towards the seabed. Numerical models have major difficulties in constraining the sinking flux of plastic to the ocean interior in these areas since validation against observational data is not possible yet.</p><p>Here, we provide the first water column profiles (0-2000m water depth) of plastic particles (>500µm) in the North Pacific subtropical gyre (Great Pacific Garbage Patch; GPGP). We show that plastic particles in the water column are mostly in the size range of particles that are apparently missing from the ocean surface and that their polymer composition is similar to that of floating debris circulating in the surface waters. Furthermore, water column plastic concentrations increase with higher concentrations at the sea surface and show a power law decline with water depth. These findings strongly suggest that plastics present in the deep sea below the GPGP are small fragments of initially buoyant plastic debris that accumulated at the sea surface. Although the amount of plastic in the GPGP water column is significant compared to the surface accumulation, our results further indicate that the ocean water column is unlikely to harbor a major fraction of the tens of millions of metric tons of missing ocean plastic.</p>

Distribution and biological implications of plastic pollution on the fringing reef of Mo’orea, French Polynesia

Coral reef ecosystems of the South Pacific are extremely vulnerable to plastic pollution from oceanic gyres and land-based sources. To describe the extent and impact of plastic pollution, the distribution of both macro- (>5 mm) and microplastic (plastic < 5 mm) of the fringing reef of an isolated South Pacific island, Mo’orea, French Polynesia was quantified. Macroplastic was found on every beach on the island that was surveyed. The distribution of this plastic was categorized by site type and by the presence of Turbinaria ornata, a common macroalgae on Mo’orea. Microplastics were discovered in the water column of the fringing reef of the island, at a concentration of 0.74 pieces m−2. Additionally, this study reports for the first time the ingestion of microplastic by the corallimorpha Discosoma nummiforme. Microplastics were made available to corallimorph polyps in a laboratory setting over the course of 108 h. Positively and negatively buoyant microplastics were ingested, and a microplastic particle that was not experimentally introduced was also discovered in the stomach cavity of one organism. This study indicates that plastic pollution has the potential to negatively impact coral reef ecosystems of the South Pacific, and warrants further study to explore the broader potential impacts of plastic pollution on coral reef ecosystems.

The deep sea is a major sink for microplastic debris

Marine debris, mostly consisting of plastic, is a global problem, negatively impacting wildlife, tourism and shipping. However, despite the durability of plastic, and the exponential increase in its production, monitoring data show limited evidence of concomitant increasing concentrations in marine habitats. There appears to be a considerable proportion of the manufactured plastic that is unaccounted for in surveys tracking the fate of environmental plastics. Even the discovery of widespread accumulation of microscopic fragments (microplastics) in oceanic gyres and shallow water sediments is unable to explain the missing fraction. Here, we show that deep-sea sediments are a likely sink for microplastics. Microplastic, in the form of fibres, was up to four orders of magnitude more abundant (per unit volume) in deep-sea sediments from the Atlantic Ocean, Mediterranean Sea and Indian Ocean than in contaminated sea-surface waters. Our results show evidence for a large and hitherto unknown repository of microplastics. The dominance of microfibres points to a previously underreported and unsampled plastic fraction. Given the vastness of the deep sea and the prevalence of microplastics at all sites we investigated, the deep-sea floor appears to provide an answer to the question— where is all the plastic?

On the Observability of Oceanic Gyres

This study examines the observability of a stratified ocean in a square flat basin on a midlatitude beta plane. Here, “observability” means the ability to establish, in a finite interval of time, the time-dependent ocean state given density observations over the same interval and with no regard for errors. The dynamics is linearized and hydrostatic, so that the motion can be decomposed into normal modes and the observability analysis is simplified. An observability Gramian (a symmetric matrix) is determined for the flows in an inviscid interior, in frictional boundary layers, and in a closed basin. Its properties are used to establish the condition for complete observability and to identify optimal data locations for each of these flows. It is found that complete observability of an oceanic interior in time-dependent Sverdrup balance requires that the observations originate from the westernmost location at each considered latitude. The degree of observability increases westward due to westward propagation of long baroclinic Rossby waves: data collected in the west are more informative than data collected in the east. Likewise, the best locations for observing variability in the western (eastern) boundary layer are near (far from) the boundary. The observability of a closed basin is influenced by the westward propagation and the boundaries. Optimal data locations that are identified for different resolutions (0.01 to 1 yr) and lengths of data records (0.2 to 20 yr) show a variable influence of the planetary vorticity gradient. Data collected near the meridional boundaries appear always less informative, from the viewpoint of basin observability, than data collected away from these boundaries.

Genetic Manipulation of Prochlorococcus Strain MIT9313: Green Fluorescent Protein Expression from an RSF1010 Plasmid and Tn5 Transposition

ABSTRACT Prochlorococcus is the smallest oxygenic phototroph yet described. It numerically dominates the phytoplankton community in the mid-latitude oceanic gyres, where it has an important role in the global carbon cycle. The complete genomes of several Prochlorococcus strains have been sequenced, revealing that nearly half of the genes in each genome are of unknown function. Genetic methods, such as reporter gene assays and tagged mutagenesis, are critical to unveiling the functions of these genes. Here, we describe conditions for the transfer of plasmid DNA into Prochlorococcus strain MIT9313 by interspecific conjugation with Escherichia coli. Following conjugation, E. coli bacteria were removed from the Prochlorococcus cultures by infection with E. coli phage T7. We applied these methods to show that an RSF1010-derived plasmid will replicate in Prochlorococcus strain MIT9313. When this plasmid was modified to contain green fluorescent protein, we detected its expression in Prochlorococcus by Western blotting and cellular fluorescence. Further, we applied these conjugation methods to show that a mini-Tn5 transposon will transpose in vivo in Prochlorococcus. These genetic advances provide a basis for future genetic studies with Prochlorococcus, a microbe of ecological importance in the world's oceans.