skip to main content


Title: The physical oceanography of the transport of floating marine debris
Abstract

Marine plastic debris floating on the ocean surface is a major environmental problem. However, its distribution in the ocean is poorly mapped, and most of the plastic waste estimated to have entered the ocean from land is unaccounted for. Better understanding of how plastic debris is transported from coastal and marine sources is crucial to quantify and close the global inventory of marine plastics, which in turn represents critical information for mitigation or policy strategies. At the same time, plastic is a unique tracer that provides an opportunity to learn more about the physics and dynamics of our ocean across multiple scales, from the Ekman convergence in basin-scale gyres to individual waves in the surfzone. In this review, we comprehensively discuss what is known about the different processes that govern the transport of floating marine plastic debris in both the open ocean and the coastal zones, based on the published literature and referring to insights from neighbouring fields such as oil spill dispersion, marine safety recovery, plankton connectivity, and others. We discuss how measurements of marine plastics (bothin situand in the laboratory), remote sensing, and numerical simulations can elucidate these processes and their interactions across spatio-temporal scales.

 
more » « less
Award ID(s):
1840868
NSF-PAR ID:
10303189
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; « less
Publisher / Repository:
IOP Publishing
Date Published:
Journal Name:
Environmental Research Letters
Volume:
15
Issue:
2
ISSN:
1748-9326
Page Range / eLocation ID:
Article No. 023003
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. It is well known that learning occurs best when students are engaged with a topic that interests them or has relevance for important aspects of their lives. In coastal California, the health of the ocean is a serious local concern, and ocean plastics are ubiquitous. We have developed a course‐based undergraduate research experience (CURE) on an existing research project addressing microbes colonizing floating plastic marine debris. The objective of the project is to increase student engagement and persistence in biology. The project (recently awarded an NSF education grant focused on Hispanic students) brings together National University (NU), an undergraduate teaching institution serving non‐traditional students, with Scripps Institution of Oceanography (SIO), a world‐renowned research‐oriented institution at UC San Diego. A modular design allows students from different biology courses (both non‐majors and majors) to participate in field and laboratory research while also interacting with research scientists and graduate students. Module contents range from classroom material including experimental design, hypothesis testing, and data analysis, to laboratory activities such as deployment of test materials, microbiology and molecular biology techniques, as well as bioinformatics. Assessment of the project involves surveys and focus groups to evaluate student engagement, as well as institutional metrics such as retention in the BS Biology program. A pilot involving a non majors general biology course visiting SIO was well‐received by students. Currently (November 2018) an extended intervention is underway with a majors general biology course. During the first week of class students learned about the research project via video material and class lectures. A half day visit to SIO provided them with field trip experience, laboratory activities, presentation about plastic research, and interactions with scientists and graduate students. In successive laboratory activities, students observed colony morphology, performed Gram stainings and colony PCR, practiced Blast searches and developed simple phylogenetic trees. We conclude that the framework can be successfully implemented in spite of time and logistical challenges. We anticipate implementing and disseminating this CURE as a widely applicable model for biology and ocean science education centered on contemporary topics of immediate interest to students. Support or Funding Information This project is funded by the NSF‐HSI grant #1832545 
    more » « less
  2. Abstract

    Plastic substrates introduced to the environment during the Anthropocene have introduced new pathways for microbial selection and dispersal. Some plastic‐colonising microorganisms have adapted phenotypes for plastic degradation (selection), while the spatial transport (dispersal) potential of plastic colonisers remains controlled by polymer‐specific density, hydrography and currents. Plastic‐degrading enzyme abundances have recently been correlated with concentrations of plastic debris in open ocean environments, making it critical to better understand colonisation of hydrocarbon degraders with plastic degradation potential in urbanised watersheds where plastic pollution often originates. We found that microbial colonisation by reputed hydrocarbon degraders on microplastics (MPs) correlated with a spatial contaminant gradient (New York City/Long Island waterways), polymer types, temporal scales, microbial domains and putative cell activity (DNA vs. RNA). Hydrocarbon‐degrading taxa enriched on polyethylene and polyvinyl chloride substrates relative to other polymers and were more commonly recovered in samples proximal to New York City. These differences in MP colonisation could indicate phenotypic adaptation processes resulting from increased exposure to urban plastic runoff as well as differences in carbon bioavailability across polymer types. Shifts in MP community potential across urban coastal contaminant gradients and polymer types improve our understanding of environmental plastic discharge impacts toward biogeochemical cycling across the global ocean.

     
    more » « less
  3. Abstract

    Many of the world's major cities are located in coastal zones, resulting in urban and industrial impacts on adjacent marine ecosystems. These pressures, which include pollutants, sewage, runoff and debris, temperature increases, hardened shorelines/structures, and light and acoustic pollution, have resulted in new evolutionary landscapes for coastal marine organisms. Marine environmental changes influenced by urbanization may create new selective regimes or may influence neutral evolution via impacts on gene flow or partitioning of genetic diversity across seascapes. While some urban selective pressures, such as hardened surfaces, are similar to those experienced by terrestrial species, others, such as oxidative stress, are specific to aquatic environments. Moreover, spatial and temporal scales of evolutionary responses may differ in the ocean due to the spatial extent of selective pressures and greater capacity for dispersal/gene flow. Here, we present a conceptual framework and synthesis of current research on evolutionary responses of marine organisms to urban pressures. We review urban impacts on genetic diversity and gene flow and examine evidence that marine species are adapting, or are predicted to adapt, to urbanization over rapid evolutionary time frames. Our findings indicate that in the majority of studies, urban stressors are correlated with reduced genetic diversity. Genetic structure is often increased in urbanized settings, but artificial structures can also act as stepping stones for some hard‐surface specialists, promoting range expansion. Most evidence for rapid adaptation to urban stressors comes from studies of heritable tolerance to pollutants in a relatively small number of species; however, the majority of marine ecotoxicology studies do not test directly for heritability. Finally, we highlight current gaps in our understanding of evolutionary processes in marine urban environments and present a framework for future research to address these gaps.

     
    more » « less
  4. Abstract

    Plastic marine debris (PMD) affects spatial scales of life from microbes to whales. However, understanding interactions between plastic and microbes in the “Plastisphere”—the thin layer of life on the surface of PMD—has been technology‐limited. Research into microbe–microbe and microbe–substrate interactions requires knowledge of community phylogenetic composition but also tools to visualize spatial distributions of intact microbial biofilm communities. We developed a CLASI‐FISH (combinatorial labelling and spectral imaging – fluorescencein situhybridization) method using confocal microscopy to study Plastisphere communities. We created a probe set consisting of three existing phylogenetic probes (targeting all Bacteria,Alpha‐, andGammaproteobacteria) and four newly designed probes (targetingBacteroidetes,Vibrionaceae,RhodobacteraceaeandAlteromonadaceae) labelled with a total of seven fluorophores and validated this probe set using pure cultures. Our nested probe set strategy increases confidence in taxonomic identification because targets are confirmed with two or more probes, reducing false positives. We simultaneously identified and visualized these taxa and their spatial distribution within the microbial biofilms on polyethylene samples in colonization time series experiments in coastal environments from three different biogeographical regions. Comparing the relative abundance of 16S rRNA gene amplicon sequencing data with cell‐count abundance data retrieved from the microscope images of the same samples showed a good agreement in bacterial composition. Microbial communities were heterogeneous, with direct spatial relationships between bacteria, cyanobacteria and eukaryotes such as diatoms but also micro‐metazoa. Our research provides a valuable resource to investigate biofilm development, succession and associations between specific microscopic taxa at micrometre scales.

     
    more » « less
  5. Abstract

    Plastic pollution has pervaded almost every facet of the biosphere, yet we lack an understanding of consumption risk by marine species at the global scale. To address this, we compile data from research documenting plastic debris ingestion by marine fish, totaling 171,774 individuals of 555 species. Overall, 386 marine fish species have ingested plastic debris including 210 species of commercial importance. However, 148 species studied had no records of plastic consumption, suggesting that while this evolutionary trap is widespread, it is not yet universal. Across all studies that accounted for microplastics, the incidence rate of plastic ingested by fish was 26%. Over the last decade this incidence has doubled, increasing by 2.4 ± 0.4% per year. This is driven both by increasing detection of smaller sized particles as a result of improved methodologies, as well as an increase in fish consuming plastic. Further, we investigated the role of geographic, ecological, and behavioral factors in the ingestion of plastic across species. These analyses revealed that the abundance of plastic in surface waters was positively correlated to plastic ingestion. Demersal species are more likely to ingest plastic in shallow waters; in contrast, pelagic species were most likely to consume plastic below the mixed layer. Mobile predatory species had the highest likelihood to ingest plastic; similarly, we found a positive relationship between trophic level and plastic ingestion. We also find evidence that surface ingestion‐deep sea egestion of microplastics by mesopelagic myctophids is likely a key mechanism for the export of microplastics from the surface ocean to the seafloor, a sink for marine debris. These results elucidate the role of ecology and biogeography underlying plastic ingestion by marine fish and point toward species and regions in urgent need of study.

     
    more » « less