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7 results on '"Valentine, Katey"'

1. Interactions between plastic pollution, microorganisms and invertebrates in freshwater systems

Author

Valentine, Katey, Boxall, Alistair, and Newbold, Lindsay

Abstract

Plastic pollution is ubiquitous throughout the environment and there is widespread concern over its impacts on aquatic ecological systems. Whilst work to understand the risks of plastic has traditionally focused on the physical and chemical characteristics of materials, the biological factors that may alter the impacts and fate of plastics have been largely overlooked, particularly within freshwater environments. Therefore, this thesis explored interactions between plastic litter, microbial communities and aquatic invertebrates within UK freshwater. Work to investigate the composition and metabolic functionality of microbial communities attached to plastic surfaces was conducted. The attraction of benthic invertebrates to microbially colonised plastic and their influence on the fate and potential impacts of plastic litter in the environment was also examined. Plastic surfaces hosted significantly distinct microbial communities compared to a non-plastic surface, and harboured communities with the potential to be pathogenic and to alter xenobiotic and biogeochemical cycling within the wider environment. These plastic-associated communities were also found to produce the odorous compound dimethyl sulfide. Given the role of this compound as a foraging cue in marine systems, this could significantly enhance the interactions which occur between plastic litter and aquatic organisms. Work to examine the influence of invertebrates on the fate of plastic in the environment found no significant interactions between microbially-colonised plastic and the amphipod Gammarus pulex. In contrast, the caddisfly larvae Agrypnia sp. rapidly fragmented plastic films (maximum diameter 6 mm) into hundreds of microplastics between 35.61 - 927.86 μm (maximum diameter), which is likely to have considerable implications for the bioavailability and fate of plastic litter in the environment. These findings demonstrate that to build an accurate and comprehensive understanding of the risks of plastic pollution in freshwater environments a better working knowledge of the biological factors which influence the fate and impacts of plastics is now urgently needed.

Published
2022

3. Using a natural capital risk register to support the funding of seagrass habitat enhancement in Plymouth Sound.

Author

Hooper, Guy, Ashley, Matthew, Mullier, Tom, Attrill, Martin, Sturgeon, Amelia, Sydenham, Zoe, Parry, Mark, Valentine, Katey, and Rees, Sian

Subjects
MARINE parks & reserves, SUSTAINABLE investing, SEAGRASS restoration, ASSET protection, SEAGRASSES, MARINE habitats, ECOSYSTEM services
Abstract

Seagrass is an important marine habitat that provides benefits to society in the form of ecosystem services. Services include the provision of food via fisheries, the regulation of water quality and the ability to sequester and store carbon. In the UK, seagrass beds are in decline, increasing the risk of ecosystem service loss. Current efforts to protect, restore and create seagrass habitat, beyond spatial management measures, rely on grant funding and donations. Emerging carbon, biodiversity and wider ecosystem service markets offering potential revenue sources could facilitate the enhancement of seagrass habitat at scale. Participation in ecosystem service markets, requires that projects deliver on the ecosystem service benefits defined. As the benefits will have been paid for, there are risks associated with not delivering on ecosystem service benefits. It is important that the risk is clearly defined. In this study we further the marine natural capital and risk register approach and apply the method to a case study area to support the development of sustainable funding options for seagrass habitat enhancement in Plymouth Sound, UK. Habitat Suitability modelling is also used to map potential areas for seagrass habitat enhancement. We find that, in the Plymouth Sound area, the risk of loss of ecosystem services for subtidal seagrass habitats is, at present, high. This is primarily linked to the declining extent and condition of subtidal seagrass assets. Under current governance, all of Plymouth Sound's subtidal seagrass are within a Marine Protected Area, though this conservation designation does not guarantee that the seagrass bed is protected from damaging activity. Under current environmental conditions there is opportunity for widespread seagrass restoration and creation. Risk to seagrass beds and any future private funding could be reduced by governance actions that enable effective direct protection of the seagrass assets and mitigate harmful pressures (e.g., reduction of water pollution). Emerging financial 'products' from seagrass ecosystem services that can support restoration and creation, require a high degree of integrity. The natural capital asset and risk register framework can provide information to underpin product development. With the development of revenue streams from ecosystem services there is a need for more intentional governance and site-based monitoring of these habitats as natural capital assets. Further research is needed to define any social or economic outcomes. Synthesis and Application: By assessing the risk to the status of seagrass assets through this approach, it is possible to determine the complementary governance actions needed to underpin investment in seagrass habitat enhancement. The methods are transferable to other locations where data exists to define the asset status. These specific findings are relevant nationally where similar vectors of risk (pressures) are identified. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Caddisfly larvae are a driver of plastic litter breakdown and microplastic formation in freshwater environments

Author

Valentine, Katey, Cross, Richard, Cox, Ruairidh, Woodmancy, Gina, Boxall, Alistair B.A., Valentine, Katey, Cross, Richard, Cox, Ruairidh, Woodmancy, Gina, and Boxall, Alistair B.A.

Abstract

Plastic litter is now pervasive in the aquatic environment. Several marine and terrestrial organisms can fragment plastic with their feeding appendages, facilitating its breakdown and generating microplastics. However, similar studies with freshwater organisms are extremely limited. We explored the interactions between the caddisfly larvae Agrypnia sp. and polylactic acid (PLA) film. The use of plastic by larvae to build their protective cases was investigated, along with their ability to fragment the plastic film as they do with leaf litter. Caddisfly consistently incorporated PLA into their cases alongside leaf material. They also used their feeding appendages to rapidly fragment PLA—forming hundreds of submillimeter-sized microplastics. Although larvae showed a preference for leaf material when constructing cases, plastic use and fragmentation still occurred when leaf material was replete, indicating that this behavior is likely to occur in natural environments that are polluted with plastics. This is thought to be the first documented evidence of active plastic modification by a freshwater invertebrate and therefore reveals a previously unidentified mechanism of plastic fragmentation and microplastic formation in freshwater. Further work is now needed to determine the extent of this behavior across freshwater taxa and the potential implications for the wider ecosystem.

Published
2022

7. Interactions Between Plastic, Microbial Biofilms and Gammarus pulex: An Initial Investigation

Author

Valentine, Katey L and Boxall, Alistair B A

Subjects
Polyethylene, Health, Toxicology and Mutagenesis, Biofilms, Animals, Amphipoda, Fresh Water, General Medicine, Toxicology, Pollution, Plastics
Abstract

There is increasing evidence that microbial biofilms which form on the surface of marine plastics can increase plastics palatability, making it more attractive to organisms. The same information, however, does not exist for freshwater systems. This study observed the response of the freshwater amphipod Gammarus pulex when exposed to 3 cm-diameter discs of biofilm-covered plastic, both alone and when presented alongside its natural food. G. pulex did not fragment or consume the plastic materials, and the presence of colonised plastic in the immediate environment did not alter the amount of time organisms spent interacting with their natural food. This study provides baseline information for virgin and microbially colonised low-density polyethylene and polylactic acid film. Further studies, with other types of plastic possessing different physical properties and with different microbial biofilm compositions are now required to build further understanding of interactions between plastic, microbial biofilms, and freshwater shredding invertebrates.

Published
2021

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