Microplastics in the seas Law, Kara Lavender; Thompson, Richard C.
Science (American Association for the Advancement of Science),
07/2014, Letnik:
345, Številka:
6193
Journal Article
Recenzirano
Concern is rising about widespread contamination of the marine environment by microplastics.
Plastic debris in the marine environment is more than just an unsightly problem. Images of beach litter ...and large floating debris may first come to mind, but much recent concern about plastic pollution has focused on microplastic particles too small to be easily detected by eye (see the figure). Microplastics are likely the most numerically abundant items of plastic debris in the ocean today, and quantities will inevitably increase, in part because large, single plastic items ultimately degrade into millions of microplastic pieces. Microplastics are of environmental concern because their size (millimeters or smaller) renders them accessible to a wide range of organisms at least as small as zooplankton, with potential for physical and toxicological harm.
The biology of Echinococcus, the causative agent of echinococcosis (hydatid disease) is reviewed with emphasis on the developmental biology of the adult and metacestode stages of the parasite. Major ...advances include determining the origin, structure and functional activities of the laminated layer and its relationship with the germinal layer; and the isolation, in vitro establishment and characterization of the multipotential germinal cells. Future challenges are to identify the mechanisms that provide Echinococcus with its unique developmental plasticity and the nature of activities at the parasite-host interface, particularly in the definitive host. The revised taxonomy of Echinococcus is presented and the solid nomenclature it provides will be essential in understanding the epidemiology of echinococcosis.
We analyzed the usefulness of rpoA, recA, andpyrH gene sequences for the identification of vibrios. Wesequenced fragments of these loci from a collection of 208representative strains, including 192 ...well-documentedVibrionaceae strains and 16 presumptive Vibrioisolates associated with coral bleaching. In order to determine theintraspecies variation among the three loci, we included severalrepresentative strains per species. The phylogenetic trees constructedwith the different genetic loci were roughly in agreement with formerpolyphasic taxonomic studies, including the 16S rRNA-based phylogeny ofvibrios. The families Vibrionaceae,Photobacteriaceae, Enterovibrionaceae, andSalinivibrionaceae were all differentiated on the basis ofeach genetic locus. Each species clearly formed separated clusters withat least 98, 94, and 94% rpoA, recA, andpyrH gene sequence similarity, respectively. The genusVibrio was heterogeneous and polyphyletic, with Vibriofischeri, V. logei, and V. wodanis groupingcloser to the Photobacterium genus. V. halioticoli-,V. harveyi-, V. splendidus-, and V.tubiashii-related species formed groups within the genusVIBRIO: Overall, the three genetic loci were morediscriminatory among species than were 16S rRNA sequences. In somecases, e.g., within the V. splendidus and V.tubiashii group, rpoA gene sequences were slightly lessdiscriminatory than recA and pyrH sequences. In thesecases, the combination of several loci will yield the most robustidentification. We can conclude that strains of the same species willhave at least 98, 94, and 94% rpoA, recA, andpyrH gene sequence similarity,respectively.
A
bstract
Poisson-Lie duality provides an algebraic extension of conventional Abelian and non-Abelian target space dualities of string theory and has seen recent applications in constructing quantum ...group deformations of holography. Here we demonstrate a natural upgrading of Poisson-Lie to the context of M-theory using the tools of exceptional field theory. In particular, we propose how the underlying idea of a Drinfeld double can be generalised to an algebra we call an exceptional Drinfeld algebra. These admit a notion of “maximally isotropic subalgebras” and we show how to define a generalised Scherk-Schwarz truncation on the associated group manifold to such a subalgebra. This allows us to define a notion of Poisson-Lie U-duality. Moreover, the closure conditions of the exceptional Drinfeld algebra define natural analogues of the cocycle and co-Jacobi conditions arising in Drinfeld double. We show that upon making a further coboundary restriction to the cocycle that an M-theoretic extension of Yang-Baxter deformations arise. We remark on the application of this construction as a solution-generating technique within supergravity.
Anthropogenic debris contaminates marine habitats globally, leading to several perceived ecological impacts. Here, we critically and systematically review the literature regarding impacts of debris ...from several scientific fields to understand the weight of evidence regarding the ecological impacts of marine debris. We quantified perceived and demonstrated impacts across several levels of biological organization that make up the ecosystem and found 366 perceived threats of debris across all levels. Two hundred and ninety‐six of these perceived threats were tested, 83% of which were demonstrated. The majority (82%) of demonstrated impacts were due to plastic, relative to other materials (e.g., metals, glass) and largely (89%) at suborganismal levels (e.g., molecular, cellular, tissue). The remaining impacts, demonstrated at higher levels of organization (i.e., death to individual organisms, changes in assemblages), were largely due to plastic marine debris (>1 mm; e.g., rope, straws, and fragments). Thus, we show evidence of ecological impacts from marine debris, but conclude that the quantity and quality of research requires improvement to allow the risk of ecological impacts of marine debris to be determined with precision. Still, our systematic review suggests that sufficient evidence exists for decision makers to begin to mitigate problematic plastic debris now, to avoid risk of irreversible harm.
Inadequate products, waste management, and policy are struggling to prevent plastic waste from infiltrating ecosystems 1, 2. Disintegration into smaller pieces means that the abundance of ...micrometer-sized plastic (microplastic) in habitats has increased 3 and outnumbers larger debris 2, 4. When ingested by animals, plastic provides a feasible pathway to transfer attached pollutants and additive chemicals into their tissues 5–15. Despite positive correlations between concentrations of ingested plastic and pollutants in tissues of animals, few, if any, controlled experiments have examined whether ingested plastic transfers pollutants and additives to animals. We exposed lugworms (Arenicola marina) to sand with 5% microplastic that was presorbed with pollutants (nonylphenol and phenanthrene) and additive chemicals (Triclosan and PBDE-47). Microplastic transferred pollutants and additive chemicals into gut tissues of lugworms, causing some biological effects, although clean sand transferred larger concentrations of pollutants into their tissues. Uptake of nonylphenol from PVC or sand reduced the ability of coelomocytes to remove pathogenic bacteria by >60%. Uptake of Triclosan from PVC diminished the ability of worms to engineer sediments and caused mortality, each by >55%, while PVC alone made worms >30% more susceptible to oxidative stress. As global microplastic contamination accelerates, our findings indicate that large concentrations of microplastic and additives can harm ecophysiological functions performed by organisms.
•Ingestion of microplastic by animals moves pollutants and additives to their tissues•Biochemically clean sand transferred more pollutants into tissues than microplastic•Uptake of pollutants, additives, and microplastic damaged ecophysiological functions
Microplastics have been documented in marine environments worldwide, where they pose a potential risk to biota. Environmental interactions between microplastics and lower trophic organisms are poorly ...understood. Coastal shelf seas are rich in productivity but also experience high levels of microplastic pollution. In these habitats, fish have an important ecological and economic role. In their early life stages, planktonic fish larvae are vulnerable to pollution, environmental stress and predation. Here we assess the occurrence of microplastic ingestion in wild fish larvae. Fish larvae and water samples were taken across three sites (10, 19 and 35 km from shore) in the western English Channel from April to June 2016. We identified 2.9% of fish larvae (n = 347) had ingested microplastics, of which 66% were blue fibres; ingested microfibers closely resembled those identified within water samples. With distance from the coast, larval fish density increased significantly (P < 0.05), while waterborne microplastic concentrations (P < 0.01) and incidence of ingestion decreased. This study provides baseline ecological data illustrating the correlation between waterborne microplastics and the incidence of ingestion in fish larvae.
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•2.9% of fish larvae (n = 347) ingested microplastics.•66% of ingested microplastics were blue fibres, mirroring trend for waterborne microplastic.•increased incidence of microplastic ingestion with proximity to coast.•increasing concentrations of waterborne microplastic with proximity to coast.•ratio of waterborne microplastics to fish larvae ranged from 27:1 nearest the coast, to 1:1 at 35 km from the coast.
We identified 2.9% of fish larvae (n = 347) had ingested microplastics (predominantly fibres) in the western English Channel. Ingested microfibers closely resembled those identified in water samples.
Plastic debris at the micro-, and potentially also the nano-scale, are widespread in the environment. Microplastics have accumulated in oceans and sediments worldwide in recent years, with maximum ...concentrations reaching 100 000 particles m3. Due to their small size, microplastics may be ingested by low trophic fauna, with uncertain consequences for the health of the organism. This review focuses on marine invertebrates and their susceptibility to the physical impacts of microplastic uptake. Some of the main points discussed are (1) an evaluation of the factors contributing to the bioavailability of microplastics including size and density; (2) an assessment of the relative susceptibility of different feeding guilds; (3) an overview of the factors most likely to influence the physical impacts of microplastics such as accumulation and translocation; and (4) the trophic transfer of microplastics. These findings are important in guiding future marine litter research and management strategies.
•Accumulation of plastic waste in the oceans has become a pressing issue.•Here we review the susceptibility of marine invertebrates to microplastic uptake.•Size, shape and abundance influence uptake; microfibres are considered most harmful.•Colonisation of microplastics could have population-level impacts.•Results will inform future marine litter research and management strategies.
Here we review microplastic uptake in marine organisms and assess individual, population and community level effects, highlighting the most susceptible species.
•First study of plastic debris in European waters during different tidal regimes.•Microplastic comprised 82% of the debris and fragments were the most common form.•The most abundant types of plastic ...were Polyethylene, Polystyrene and Polypropylene.•There was significant shift towards smaller plastic sizes during the neap/ebb tide.•During our study river Tamar did not identify as a net source or sink.
The majority of plastic debris found in the marine environment has land based sources and rivers are considered an important medium for transfer of this debris. Here we report on the quantity and composition of floating plastic debris collected from surface waters of the Tamar Estuary. This represents the first study of riverine transport of floating plastic debris into European waters during different tidal regimes. Plastics were found in a variety of forms and sizes and microplastics (<5mm) comprised 82% of the debris. The most abundant types of plastic were Polyethylene (40%), Polystyrene (25%) and Polypropylene (19%). There was a significant difference in size frequency distribution between the spring and neap tides with more fragments of larger size observed during spring tides. While it is clear that debris has accumulated on shorelines within the estuary, during our study this river did not identify as a net source or sink.
A
bstract
The worldsheet theories that describe Poisson-Lie T-dualisable
σ
-models on group manifolds as well as integrable
η
,
λ
and
β
-deformations provide examples of ℰ-models. Here we show how ...such ℰ-models can be given an elegant target space description within Double Field Theory by specifying explicitly generalised frame fields forming an algebra under the generalised Lie derivative. With this framework we can extract simple criteria for the R/R fields and the dilaton that extend the ℰ-model conditions to type II backgrounds. In particular this gives conditions for a type II background to be Poisson-Lie T-dualisable. Our approach gives rise to algebraic field equations for Poisson-Lie symmetric spacetimes and provides an effective tool for their study.
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