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Cumulative effects assessment for fish

It should be noted that the Sankey plots and associated narratives in this thematic assessment are an illustrative representation of a complex set of interactions between DAPSIR components at the coarse North-East Atlantic scale and should be considered and interpreted alongside the supporting full thematic assessment narrative. The Sankey plots should thus be applied with caution and not considered or used as the sole basis for management decisions.

A range of human activities contribute pressures with the cumulative potential to affect the state of fish and associated ecosystem services (with consequences for societal drivers such as food, energy, space, health and biodiversity). Extraction, mortality and injury affecting wild species is the predominant pressure. Others include those from climate change  (i.e., changes in temperature regimes, stratification and circulation patterns, acidification, nutrient enrichment, changes in water chemistry); input of other substances; input of litter; input of microbial pathogens; physical disturbance of the seabed; habitat loss; input of anthropogenic sound; changes to hydrological condition; input or spread of NIS; input of water and input of nutrients, but there is lower confidence in ranking their relative importance. Following a Driver-Activity-Pressure-State-Impact-Response (DAPSIR) framework and a weighting exercise, an indicative assessment of cumulative effects has been undertaken (see CEMP Guideline for details) as a first step to describing the potential pathways of cumulative causes and the consequences of change in the ecosystem, linking these to impacts on ecosystem services. 

The current thematic assessment describes the connectivity between the relevant DAPSIR components. Sankey diagrams provide a schematic of potential impact pathways describing cumulative causes and consequences of change in the ecosystem, demonstrating that multiple human activities are contributing to multiple pressures which can lead to multiple impacts on the state of fish and associated ecosystem services (see CEMP Guideline for details). A better understanding of this complexity in the causes and consequences of cumulative effects from human activities on ecosystem state and ecosystem services is critical in order to explicitly apply the ecosystem approach to target management measures appropriately.

The evidence underpinning the analyses described in this chapter is drawn from the Driver, Activity, Pressure, State, Impact and Response chapters of this thematic assessment, and should be read and interpreted alongside the extended narratives provided therein. The Human activities and Pressures sections of this thematic assessment provide detail of the threats that the left-hand side of the Sankey plot (Figure CE.1) pose to fish. The State section of this thematic assessment provides details of ecosystem state, shown in the centre of the Sankey plot (Figure CE.1), illustrated for fish. The right-hand side of Figure CE.1 incorporates the impact on ecosystem service scores to present the Activity, Pressure, State and Impact components of the fish ‘ecosystem’ in a single plot. This is consistent with NEAES operational objective S7.O3 on ecosystem services and natural capital, “to recognise, assess and consistently account for human activities and their consequences in the implementation of ecosystem-based management.”

Figure CE.1 shows the complex combinations of human activities and pressures on state changes (left-hand side) and those of state changes on ecosystem services (right-hand side). However, there is currently insufficient understanding and evidence to be able to directly track from left to right, hence the single bar in the centre. This should be a focus of future assessments.

Overall, confidence in the evidence for the weighted bow tie analysis outputs presented in the Fish Thematic Assessment is described as medium for evidence and medium/low for degree of agreement. Additionally, separate confidence assessments have been applied to each module.

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Figure CE.1: Impact Potential of Fish to exposure to pressures from human activities in the North-East Atlantic. Columns left to right: Activity, Pressure, State, Environmental Impact, Ecosystem Service. Derived from Exposure score (Extent x Frequency of pressure) x Degree of Impact score (in terms of whether impact is Acute or Chronic). Pressures with a low Degree of Impact score have been removed for clarity. ‘Impact’ in this context does not consider the persistence of the pressure or the resilience of the ecosystem associated with that pressure. Were these parameters to be included, the relative contribution for some pressures would most likely increase and score higher in the relative ranking. Links are weighted to indicate relative contribution to impact. A wider link = greater potential for impact

It should be noted that the Sankey plots and associated narratives in this thematic assessment are an illustrative representation of a complex set of interactions between DAPSIR components at the coarse North-East Atlantic scale and should be considered and interpreted alongside the supporting full thematic assessment narrative. The Sankey plots should thus be applied with caution and not considered or used as the sole basis for management decisions.
 

Figure CE.1 demonstrates the complex relationships which the collective pressures from human activities have on the quality status of fish. This complexity suggests that while single-issue responses may be effective, in order to fully apply ecosystem-based management OSPAR needs to consider the causes and consequences of changes in ecosystem state more holistically,  

  • recognising that any measures to reduce impacts, while critical to ecosystem health, could have potential consequences for the ability to maintain ecosystem services to meet society’s needs, which in turn has consequences for the viability of human activities in the North-East Atlantic; and
  • recognising that pressures may have additive, multiplicative, synergistic or antagonistic interactions when combined, which has implications for the nature of the threats posed to fish and how best to manage those threats

Methodology

A modified bow-tie analysis (Cormier et al., 2018; Cormier et al., 2019) was developed to identify and connect all the DAPSIR components, integrating these into either a pressure-focused (e.g., underwater sound, litter, hazardous substances, eutrophication) or a biodiversity receptor focused (e.g., pelagic habitats, benthic habitats, fish, marine birds, marine mammals) analysis of the causes and consequences of change. For the biodiversity assessments, the APS connections are weighted to determine the most important, using an adaptation of the ODEMM pressure assessment (Robinson et al., 2013; Knights et al., 2015) focusing on:

  1. Exposure module: spatial extent and frequency for all activity pressure combinations on state, to generate exposure weightings;
  2. Impact potential module: spatial extent, frequency of occurrence and impact potential for all activity pressure combinations on state, to generate impact potential weightings;
  3. Risk module: spatial extent, frequency of occurrence, impact potential for all activity pressure combinations on state, combined with pressure persistence and ecosystem resilience, to generate risk weightings.

The SI (ecosystem services) connections are weighted to determine which are the most important (Cornaccia, 2022).

The impact potential and ecosystem services outputs are combined and presented in Sankey diagrams (Figure CE.1).

Confidence in this weighted bow-tie analysis exercise for fish has been assessed in accordance with the QSR 2023 Guidance Document. Confidence is based on two criteria to communicate the degree of uncertainty in the key findings: (i) level of evidence (determined by considering the type, amount, quality, and consistency of evidence, i.e., robust, medium, or limited) and (ii) degree of agreement (i.e., high, medium or low).

Exposure module:

Confidence Assessment: Evidence – Medium; Consensus – Medium

Pressures from human activities have been demonstrated in the assessments for this QSR to be widely distributed in the OSPAR Maritime Area. The presence of pressures does not automatically lead to adverse impacts. However, in the first instance consideration of the spatial and temporal extents of pressures provides a useful basis for the consideration of cumulative effects within a risk-based approach (in line with the North-East Atlantic ecosystem principle and strategic approach). 

The exposure module describes the extent of the pressure from human activities in the North-East Atlantic. It considers the spatial extent and frequency of the human activity pressure combinations which have been identified as important for fish (derived from spatial extent score multiplied by frequency score). Exposure relates only to the pressure cell in the DAPSIR schema (Figure CE.1). The consideration of exposure in isolation provides a coarse cross-cutting assessment, providing an early identification which allows OSPAR to develop management strategies for pressures in order to prevent / minimise impacts. 

The thematic assessments for Hazardous Substances, Eutrophication, Marine Litter, Underwater Noise, Offshore Industry, Climate Change and the Ocean Acidification Other Assessment describe pressures on fish. The Radioactive Substances Thematic Assessment identifies inputs of radionuclides from a range of human activities but has concluded that there are no significant radiological impacts on biodiversity from the current levels of radionuclides.

Climate Change and Ocean Acidification pressures have been identified as important for fish.

Input of substances, input of litter, input of microbial pathogens, anthropogenic sound, input of radionuclides and disturbance of species are also important and their exposure scores are among the highest, demonstrating the ubiquitous nature of these pressures in the North-East Atlantic. Extraction of species, physical disturbance of the seabed, habitat loss, and input of other forms of energy also have high exposure scores.

The exposure scores support the importance that OSPAR places on these pressures in its North-East Atlantic Environment Strategy 2030:

Multiple human activities have been identified as exerting these pressures in the North-East Atlantic. Any actions to manage these pressures in order to prevent or reduce impacts on state, either individually or cumulatively (collectively), will need to consider if and how these human activities might best be targeted (and the consequences for the associated drivers and ecosystem services) within an Ecosystem Approach.

Impact potential module:

Confidence Assessment: Evidence – Medium; Consensus – Medium/Low

Impact potential is incorporated with the exposure module (spatial extent and frequency) for pressures from specified human activities (derived from the aggregated exposure score multiplied by the degree of impact score).  Impact potential here relates to generic interaction in terms of a pressure’s likely effects on the ecological component, in the categories of: low potential for significant impact, chronic impact or acute impact (Robinson et al., 2013). Figure CE.1 shows the combined weighted scores for exposure and impact potential. 

Any activity-pressure combination with a Degree of Impact score of Low was filtered out, following discussion with the expert group. For example, the input of radionuclides has been filtered out based on the conclusions in the Radioactive Substances Thematic Assessment as these have been demonstrated to have low potential for significant impact based on the available evidence. Other pressures filtered out as having low potential for significant impact are changes to hydrological conditions from fishing activities; disturbance of species from coastal and flood protection; extraction of oil and gas, non-renewable energy generation; tourism and leisure activities and infrastructure, transport – shipping; habitat loss from aquaculture – freshwater, navigation dredging, coast and flood protection, land claim, tourism and leisure infrastructure, transport infrastructure; anthropogenic sound from renewable energy generation and transport – shipping; marine litter from tourism and leisure activities; microbial pathogens from tourism and leisure activities; nutrients from extraction of minerals and oil and gas, forestry, industrial uses; input of other forms of energy from extraction of oil and gas; input of other substances from extraction of minerals and oil and gas, transport – land; and physical disturbance of the seabed from subsea cables.

The relative ranking of pressures changes when impact is considered (Figure CE.1). Fish mortality and injury associated with fisheries activities is ranked highest. Climate change pressures also rank highly (see the Climate Change Thematic Assessment for detail on contributing human activities).  The Pressures section of this thematic assessment describes the importance of pressures to fish and corroborates the importance of fish mortality and injury and climate change pressures. While the weighted bow-tie analysis has identified relative rankings for other pressures, the OSPAR Fish Expert Group considers that limited evidence exists to confirm these relative rankings. It is thus concluded that the other pressures shown in Figure CE.1 should be considered of equal importance until further evidence can be provided (e.g., input of substances, input of litter, input of microbial pathogens, anthropogenic sound and disturbance of species).

Risk module:

Confidence Assessment:  Evidence – Low; Consensus – Low

Given the low confidence scoring, the outputs from the risk analyses have not been included in this thematic assessment for QSR 2023. However, it is beneficial to consider the agreed outputs of the persistence weightings. Details of the criteria applied in the risk module are described in the CEMP Guideline.

Regional summary of likely cumulative effects

Confidence Assessment: Evidence – High; Consensus – Medium

While the weighted bow-tie analyses displayed in the Sankey diagrams have been produced at the North-East Atlantic scale, consideration can be given to where regional differences may arise by cross-referencing other assessments in QSR 2023.

The Fish Thematic Assessment identifies the cumulative pressures for fish (but no regional breakdown of pressures was attempted there) in terms of both exposure and impact.

The list below summarises the main pressures impacting fish, with information on associated activities. Note that activity-pressure combinations scored as low-impact on the basis of current available evidence were filtered out from the Sankey diagram in Figure CE.1. However, the activity-pressure links listed below relate to the unfiltered outputs used in the Exposure assessment.

  • Climate change and ocean acidification pressures;
  • Extraction of, or mortality to, wild species from fish and shellfish harvesting;
  • Physical disturbance of the seabed from renewable energy generation; extraction of oil and gas; restructuring of seabed morphology; transmission of electricity and communications; fish and shellfish harvesting;
  • Disturbance of species from renewable energy generation; extraction of oil and gas; non-renewable energy generation (Nuclear); extraction of minerals; transport – shipping; tourism and leisure activities and infrastructure; fish and shellfish harvesting;
  • Input of other substances from research, survey and educational activities; transport – land; military operations; extraction of oil and gas; waste water treatment and disposal; non-renewable energy generation (Nuclear); transport – shipping; urban uses and industrial uses;
  • Input of anthropogenic sound from renewable energy generation; extraction of oil and gas and transport – shipping;
  • Input of nutrients from industrial uses; agriculture and forestry;
  • Habitat loss from tourism and leisure infrastructure; aquaculture – marine; aquaculture – freshwater; canalisation and other water course modification; coastal protection and flood defence; land claim; transport infrastructure;
  • Input of microbial pathogens from transport – shipping; urban uses; industrial uses; tourism and leisure activities; fish and shellfish harvesting; aquaculture – marine;
  • Input or spread of NIS from transport – shipping; aquaculture – marine;
  • Input of other forms of energy from extraction of oil and gas and non-renewable energy generation (nuclear);
  • Input of water from waste water treatment and disposal and non-renewable energy generation (nuclear);
  • Changes in hydrological conditions from non-renewable energy generation (nuclear); fish and shellfish harvesting;
  • Input of litter from transport – shipping; urban uses; industrial uses; tourism and leisure activities; fish and shellfish harvesting; aquaculture – marine.

OSPAR does not have evidence on all human activities, but the regional breakdown of relative intensities for the activities Agriculture; Aquaculture; Extraction of minerals (aggregates); Oil and Gas; Nuclear; Renewable Energy; Fisheries and Shipping have been extracted from the supporting evidence for QSR 2023 and are summarised below. The direct influence of the cumulative pressures from these activities on fish is likely to follow similar trends in intensity within these Regions. Pressures spread beyond the spatial extent of these human activities, but insufficient evidence is currently available, and consequently trends in indirect cumulative pressures have not been considered.

The Offshore Industry Thematic Assessment describes:

  • low relative intensity of Oil and Gas sector activity in the Bay of Biscay and Iberian Coast (Region IV) and Wider Atlantic (Region V);
  • moderate relative intensity of Oil and Gas sector activity in Arctic Waters (Region I) and Celtic Seas (Region III);
  • high relative intensity of Oil and Gas sector activity in the Greater North Sea (Region II).

The Human Activities Thematic Assessment describes:

  • low relative intensity of Aggregate Extraction sector activity in Arctic Waters (Region I) and the Wider Atlantic (Region V);
  • moderate relative intensity of Aggregate Extraction sector activity in the Celtic Seas (Region III) and Bay of Biscay and Iberian Coast (Region IV);
  • high relative intensity of Aggregate Extraction sector activity in the Greater North Sea (Region II);
  • moderate relative intensity of Agriculture sector activity in the Celtic Seas (Region III) and Bay of Biscay and Iberian Coast (Region IV);
  • high relative intensity of Agriculture sector activity in the Greater North Sea (Region II);
  • low relative intensity of Aquaculture sector activity in the Wider Atlantic (Region V);
  • moderate relative intensity of Aquaculture sector activity in the Celtic Seas (Region III) and Bay of Biscay and Iberian Coast (Region IV);
  • high relative intensity of Aquaculture sector activity in Arctic Waters (Region I) and the Greater North Sea (Region II);
  • low relative intensity of Fisheries sector activity in the Wider Atlantic (Region V);
  • moderate relative intensity of Fisheries sector activity in the Bay of Biscay and Iberian Coast (Region IV);
  • high relative intensity of Fisheries sector activity in Arctic Waters (Region I), the Greater North Sea (Region II) and Celtic Seas (Region III);
  • low relative intensity of Offshore Renewable Energy sector activity in the Bay of Biscay and Iberian Coast (Region IV);
  • moderate relative intensity of Offshore Renewable Energy sector activity in the Celtic Seas (Region III);
  • high relative intensity of Offshore Renewable Energy sector activity in the Greater North Sea (Region II);
  • low relative intensity of Tourism sector activity in Arctic Waters (Region I) and the Wider Atlantic (Region V);
  • moderate relative intensity of Tourism sector activity in the Celtic Seas (Region III);
  • high relative intensity of Tourism sector activity in the Greater North Sea (Region II) and Bay of Biscay and Iberian Coast (Region IV);
  • low relative intensity of Transport and Shipping sector activity in the Wider Atlantic (Region V);
  • moderate relative intensity of Transport and Shipping sector activity in Arctic Waters (Region I);
  • high relative intensity of Transport and Shipping sector activity in the Greater North Sea (Region II), Celtic Seas (Region III) and Bay of Biscay and Iberian Coast (Region IV).

The Radioactive Substances Thematic Assessment describes:

  • no Nuclear sector activity in the Wider Atlantic (Region V);
  • low relative intensity of Nuclear sector activity in Arctic Waters (Region I);
  • moderate relative intensity of Nuclear sector activity in the Bay of Biscay and Iberian Coast (Region IV);
  • high relative intensity of Nuclear sector activity in the Greater North Sea (Region II) and Celtic Seas (Region III).

Regional evidence for trends in the intensity of other human activities or for climate change and ocean acidification was not available in sufficient detail to be utilised in this assessment.

ResponseClimate Change