Plastic waste has been documented in nearly all types of marine environments and has been found in species spanning all levels of marine food webs. Within these marine environments, deep pelagic waters encompass the largest ecosystems on Earth. We lack a comprehensive understanding of the concentrations, cycling, and fate of plastic waste in sub-surface waters, constraining our ability to implement effective, large-scale policy and conservation strategies. We used remotely operated vehicles and engineered purpose-built samplers to collect and examine the distribution of microplastics in the Monterey Bay pelagic ecosystem at water column depths ranging from 5 to 1000 m. Laser Raman spectroscopy was used to identify microplastic particles collected from throughout the deep pelagic water column, with the highest concentrations present at depths between 200 and 600 m. Examination of two abundant particle feeders in this ecosystem, pelagic red crabs (Pleuroncodes planipes) and giant larvaceans (Bathochordaeus stygius), showed that microplastic particles readily flow from the environment into coupled water column and seafloor food webs. Our findings suggest that one of the largest and currently underappreciated reservoirs of marine microplastics may be contained within the water column and animal communities of the deep sea.
Pollution and Marine Debris
Marine biodiversity is under increasing threat as the area covered by corals diminishes under pressure from climate change and human activities, most of which lead to marine pollution. In Kenya, marine protected areas (MPAs) are the key strategy used to protect coral reefs and biodiversity. However, MPAs' effectiveness to prevent pollution of the reefs has not been specifically assessed. We determined if the levels of surrogates of human-source pollution, i.e., E. coli and nutrient concentrations on Kenyan coral reefs, varied with increasing levels of marine protection at the Kilifi creek (least protection), Malindi Reserve (moderate protection), and Kuruwitu Conservancy (strictest protection). The most probable number (MPN) of E. coli was estimated by serial dilution while nitrate and orthophosphate concentrations were determined spectrophotometrically. As protection increased from “least,” to “moderate” and “strictest,” E. coli concentrations (MPN/100 mL) decreased from 29, to 16 and undetectable, while mean orthophosphate concentrations increased from 0.326, to 0.422 and 0.524 mg/L, respectively. Mean nitrate concentrations, on the other hand, showed no trend with protection. These results suggest the potential of marine protection to mitigate coral reef pollution, especially from microbes. They also point to the possibility that multiple sources of pollution exist on which marine protection may have little or no effect. Significantly, this pilot study points to the need for improved study design to definitively determine the role MPAs may play in protecting against pollution.
Toxic chemicals within and adsorbed to microplastics (0.05–5 mm) have the potential to biomagnify in food webs. However, microplastic concentrations in highly productive, coastal habitats are not well understood. Therefore, we quantified the presence of microplastics in a benthic community and surrounding environment of a remote marine reserve on the open coast of California, USA. Concentrations of microplastic particles in seawater were 36.59 plastics/L and in sediments were 0.227 ± 0.135 plastics/g. Densities of microplastics on the surfaces of two morphologically distinct species of macroalgae were 2.34 ± 2.19 plastics/g (Pelvetiopsis limitata) and 8.65 ± 6.44 plastics/g (Endocladia muricata). Densities were highest in the herbivorous snail, Tegula funebralis, at 9.91 ± 6.31 plastics/g, potentially due to bioaccumulation. This study highlights the need for further investigations of the prevalence and potential harm of microplastics in benthic communities at remote locations as well as human population centers.
The presence and effects of plastic debris is increasingly investigated. The majority of studies focuses on microplastics (MPs), but few reports suggest that plastic fragments in the <100 nm size range, referred to as nanoplastics (NPs), may also be formed in the aquatic environment and further to humans. This paper provides a review on routes of human exposure and potential effects of MPs and NPs to human health. MPs/NPs could potentially induce: physical damages through particles itself, and biological stress through MPs/NPs alone or leaching of additives (inorganic and organic). Future research should evaluate trophic transfer of MPs/NPs with their associated chemicals through the marine food web.
The hypothesis that carnivorous consumers associated with the seabed are more likely to ingest marine debris was tested based on stomach content analysis of fish(Trichiurus lepturus and species of Ariidae) and cetaceans (Sotalia guianensis and Pontoporia blainvillei). Among 596 stomach contents, only 22 (3.7%) contained debris. The debris was flexible plastic, nylon yard, paper, latex, styrofoam and cigarettefilter. The proportion of stomach contents with debris varied among species: P. blainvillei (pelagic demersal consumer) presented the highest frequency of ingestion(15.7%), while T. lepturus (pelagic consumer), S. guianensis (pelagic consumer) and Ariidae (demersal consumer) presented similar frequencies (1.3–1.8%). Therefore, a feeding site in the water column does not predict the probability of debris ingestion. Concerning these species, this probability seems to be more associated with prey-capture strategies (or feeding behavior), regardless of debris availability in the environment.
Shoreline litter is one of the most widespread pollution problems today. Since shorelines represent very sensitive and large geographical areas, any organized cleanup event requires considerable manpower in order to be successful. This case study illustrates how Vancouver Aquarium and World Wildlife Foundation recruited, organized, and retained tens of thousands of volunteers in order to build a shoreline cleanup movement across Canada.
Knowledge on microplastic (MP) ingestion by cetaceans is difficult to obtain. We infer the potential for MP uptake by cetaceans from the occurrence of MP in prey species. First, we reviewed information on whale prey species, focussing on common minke (Balaenoptera acutorostrata) and sei whale (B. borealis), for which the most comprehensive quantitative datasets exist. Second, evidence of MP ingestion by their prey species was reviewed. We found common minke whales forageopportunistically on fish from various families: Ammodytidae, Clupeidae, Gadidae, Engraulidae and Osmeridae. Sei whales mostly feed on copepods, Engraulidae, Clupeidae and Scombridae. High levels of MP contamination are reported for Scombridae in the Atlantic and Engraulidae in the Northwest Pacific Ocean. Copepods exhibit low levels of MP ingestion in the Northeast Pacific Ocean. Species-specific prey preferences and feeding strategies imply different cetaceans have varied potential for MP uptake, even if they feed in similar geographic areas.
There is considerable scientific and societal concern about plastic pollution, which has resulted in citizen science projects to study the scale of the issue. Citizen science is a cost-effective way to gather data over a large geographical range while simultaneously raising public awareness on the problem. Because the experiences of researchers involved in these projects are not yet adequately covered, this paper presents the findings from ten semi-structured qualitative interviews with researchers leading a citizen science project on micro- or macroplastics. Our results show it is important to specify the goal(s) of the project and that expertise on communication and data science is needed. Furthermore, simple protocols, quality control, and engagement with volunteers and the public are key elements for successful projects. From these results, a framework with recommendations was drafted, which can be used by anyone who wants to develop or improve citizen science projects.
In this study, a general methodology that is based on numerical models and statistical analysis is developed to assist in the definition of marine litter cleanupand mitigation strategies at an estuarine scale. The methodology includes four main steps: k-means clustering to identify representative metocean scenarios; dynamic downscaling to obtain high-resolution drivers with which to force a transport model; numerical transport modelling to generate a database of potential litter trajectories; and a statistical analysis of this database to obtain probabilities of litter accumulation. The efficacy of this methodology is demonstrated by its application to an estuary along the northern coast of Spain by comparing the numerical results with field data. The necessary criteria to ensure its applicability to any other estuarywere provided. As the main conclusion, the developed methodology successfully assesses the litter distribution in estuaries with minimum computational effort.
Understanding and engaging the public is key for ensuring the success of government and industry initiatives aimed at addressing the problem of plastic waste. However, there has been little focus on documenting the general public’s attitudes towards plastics. This study examines public beliefs and attitudes towards plastics in Australia and provides insight on a global level. The research was conducted using an online survey of a nationally representative sample (2518 respondents). Overall, the survey results indicate that the public view plastics as a serious environmental issue. Plastic in the ocean had the highest mean rating for seriousness out of nine environmental issues, followed by two other issues relating to plastic waste production and disposal. Whilst there was an association of plastics with food packaging and convenience, there was more of a negative association with the use of plastic overall. Eighty percent of respondents indicated a desire to reduce plastic use and the majority of respondents believe that paper and glass are more environmentally friendly packaging materials than plastics. However, the results showed that many respondents do not translate their aspiration to reduce plastic use into action. Overall, while a majority of the Australian public are concerned about plastics as an environmental issue, they place the bulk of the responsibility for reducing the use of disposable plastic on industry and government.