Bow-tie analysis
The Bow-tie diagram aligns with the DAPSIR narrative in the TA - provisional confidence assessment: Medium (Medium Agreement on DAPSIR content + Medium Evidence to support connections) based on approach described in Agreement 2019-02.
The bow-tie analysis for marine litter shows the relationships between the DAPSIR components which need to be considered in a cumulative effects assessment. Human activities have been identified which contribute to marine litter pressures with the potential to both individually and cumulatively contribute to biodiversity state changes in the thematic assessments for:
Benthic Habitats - Input of litter:
Marine litter (including plastics) can lead to smothering of benthic habitats and generation of artificial hard substrate altering the structure of benthic communities and leading to loss of biodiversity.
Fish - Input of litter (solid waste matter, including micro-sized litter):
The land-based introduction of litter (e.g. rivers, industrial sources, tourism) and marine-based introduction of litter (shipping, fishing, aquaculture) can cause ingestion and entanglement leading to injury or death. Input of litter into the environment can also cause diseases affecting fish species.
Marine Birds - Input of litter (solid waste matter, including micro-sized litter):
The land-based introduction of litter (e.g. rivers, industrial sources, tourism) and marine-based introduction of litter (e.g., shipping, fishing, aquaculture) can cause ingestion, presence of plastic in seabirds’ stomachs and entanglement leading to injury or death (including reduced reproductive rate due to entanglement in plastics used as nest material). Input of litter into the environment can also cause habitat loss of breeding and nesting sites, alterations to suitable foraging habitat and diseases, affecting seabird abundance.
Marine Mammals - Input of litter (solid waste matter, including micro-sized litter):
The land-based introduction of litter (e.g., rivers, industrial sources, tourism) and marine-based introduction of litter (e.g., shipping, fishing, aquaculture) can cause ingestion and entanglement leading to injury or death. For example, if a marine mammal gets caught in lost fishing nets, it can cause injuries, reduced movement or even drowning. Input of litter into the environment can also cause diseases affecting marine mammal abundance.
NIS - Input of litter (solid waste matter, including micro-sized litter):
Marine litter also contributes to the input/spread of non-indigenous species by providing mobile artificial substrate that can transport non-indigenous species from location to location.
The State section describes the potential ecological impacts associated with marine litter in the marine environment. The input levels, frequency of occurrence, spatial extent, and exposure to different human activities all collectively contribute to the extent to which marine litter pressures are exerted on benthic habitats, fish, marine birds and marine mammals, and marine litter can facilitate the spread of NIS. To undertake a full quantitative analysis of cumulative effects requires consideration of the exposure pathways and ecological impacts. Further analyses and evidence of ecological impacts are required in order to progress the assessment of cumulative effects.
Marine litter can also combine with other pressures to collectively affect marine species and habitats. The assessment of cumulative effects is considered within the following biodiversity thematic assessments:
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