Marine Mammals Thematic Assessment

Cumulative effects assessment for marine mammals

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 (Driver-Activity-Pressure-State-Impact-Response) 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 which cumulatively have the potential to impact the state of marine mammals and associated ecosystem services (with consequences for societal drivers, e.g., food, energy, space, health, biodiversity). The extraction of or mortality/injury to species, input of anthropogenic sound, disturbance of species, prey depletion, input of litter and input of substances are the predominant pressures. 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 potential pathways of cumulative causes and consequences of change in the ecosystem linking these to impacts on ecosystem services. 

The Marine Mammals Thematic Assessment describes the connectivity between the relevant DAPSIR components. The bow-tie analysis provides a schematic of potential impact pathways describing the 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 marine mammals and the associated ecosystem services. A better understanding of this complex pattern surrounding the effect of human activities on ecosystem state and ecosystem services is critical if OSPAR is to explicitly apply the ecosystem approach in order 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 it should thus be read and interpreted alongside the extended narratives provided therein. The Human activities and Pressure  sections of this thematic assessment provide detail on the threats that the left-hand side of the Sankey plot (Figure CE.1) poses to marine mammals. The State section of this thematic assessment provides details of the ecosystem state shown in the centre of the Sankey plot (Figure CE.1) illustrated for marine mammals. The right-hand side of Figure CE.1 incorporates the impact on ecosystem service scores so as to present the APSI components of the marine mammal “ecosystem” in a single plot. This is consistent with North-East Atlantic Environment Strategy (NEAES) 2030  Operational Objective S7.O3: “By 2025 OSPAR will start accounting for 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 and pressures on state changes (left-hand side) and 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 study to inform future assessments. 

Overall, confidence in the evidence for the weighted bow-tie analysis outputs presented in this marine mammal thematic assessment are described as medium for evidence and medium for degree of agreement. Additionally, separate confidence assessments have been applied to each module.

Figure CE.1a: Impact potential of marine mammals for 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 i 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 will 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.1b: Unweighted assessment of the contribution of climate change and greenhouse gas emissions to pressures affecting marine mammals in the North-East Atlantic. Columns left to right: Activity, Pressure, State, Environmental Impact, Ecosystem Service

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

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

Methodology

CEMP Guideline

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- (e.g. underwater sound, litter, hazardous substances, eutrophication) or a biodiversity receptor- focused analysis of the causes and consequences of change (e.g. pelagic habitats, benthic habitats, fish, marine birds, marine mammals). For the biodiversity assessments, the APS connections are weighted to determine which are the most important, using an adaptation of the Options for Delivering Ecosystem-Based Marine Management (ODEMM) pressure assessment (Robinson et al., 2013 and 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 marine mammals has been assessed following the QSR 2023 guidance. Confidence is based on two criteria to communicate the degree of uncertainty in the key findings: (i) level of evidence and (ii) degree of agreement.

Exposure module

Confidence Assessment: Evidence – Medium; Consensus – Medium

Pressures from human activities have been demonstrated in the assessments for the QSR 2023 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 our consideration of cumulative effects within a risk-based approach (in line with the North-East Atlantic Environment Strategy 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 that have been identified as important for marine mammals (derived from spatial extent score multiplied by the frequency score). Exposure only relates to the pressure cell in the DAPSIR schema (Figure CE.1). Consideration of exposure in isolation provides a coarse cross-cutting assessment to provide an early identification which allows OSPAR to develop management strategies for pressures to prevent / minimise impacts. 

The: Hazardous Substances Thematic Assessment , Marine Litter Thematic Assessment , Underwater Noise Thematic Assessment , Offshore Industry Thematic Assessment , Human Activities Thematic Assessment , and Climate Change Thematic Assessment describe pressures on marine mammals. The Radioactive Substances Committee 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 ( Climate Change Thematic Assessment ) and Ocean Acidification pressures have been identified as important for marine mammals (Marine Mammals Thematic Assessment – Climate Change). 
Input of anthropogenic sound, disturbance of species, input of radionuclides, input of litter, input of substances and extraction of, or mortality/injury to, wild species; physical disturbance of the seabed; and input of nutrients are also important and have the highest exposure scores, demonstrating the ubiquitous nature of some of these pressures in the North-East Atlantic.

The exposure scores support the importance that OSPAR places on these pressures under the North-East Atlantic Environment Strategy (NEAES) 2030:

• Strategic Objective 1 intended to tackle eutrophication through limiting inputs of nutrients and organic matter (and the work of the Hazardous Substances and Eutrophication Committee ( Eutrophication Thematic Assessment ).
• Strategic Objective 2 intended to prevent pollution by hazardous substances (and the work of the Hazardous Substances and Eutrophication Committee ( Hazardous Substances Thematic Assessment ) and the Offshore Industry Committee ( Offshore Industry Thematic Assessment )).
• Strategic Objective 3 intended to prevent pollution by radioactive substances (and the work of the Radioactive Substances Committee ( Radioactive Substances Committee Thematic Assessment )).
• Strategic Objective 4 intended to prevent inputs and significantly reduce marine litter ( Marine Litter Thematic Assessment ) (and the work of the Environmental Impacts of Human Activities Committee ( Human Activities Thematic Assessment )).

Strategic Objective 5 intended to protect and conserve marine biodiversity and ecosystems (this Marine Mammals thematic assessment and the work of the Biodiversity Committee, including the other biodiversity thematic assessments: Pelagic Habitats Thematic Assessment , Benthic Habitats Thematic Assessment , Fish Thematic Assessment , Marine Birds Thematic Assessment , Food webs Thematic Assessment .

• Strategic Objective 8 intended to reduce anthropogenic underwater noise ( Underwater Noise Thematic Assessment ) (and the work of the Environmental Impacts of Human Activities Committee ( Human Activities Thematic Assessment )).
• Strategic Objective 9 intended to safeguard the structure and functions of the seabed/marine ecosystems by preventing significant habitat loss and physical disturbance (this Marine Mammals thematic assessment and the work of the Biodiversity Committee, including the benthic habitats thematic assessments ( Benthic Habitats Thematic Assessment )). 
• Strategic Objectives 10 intended to raise awareness of climate change and ocean acidification; 11 to facilitate adaptation to the impacts of climate change and ocean acidification; and 12 to mitigate climate change and ocean acidification.

Multiple human activities have been identified as exerting these pressures in the North-East Atlantic. Any actions to manage these pressures and 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 (CEMP Guideline).

Impact potential module:

Confidence Assessment: Evidence – Medium; Consensus – High

The 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 the generic severity of the interaction in terms of its effects on the ecological component expressed 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 combinations with a Degree of Impact score of Low was filtered out, following discussion with the expert group.  This is the case with the input of radionuclides, for example, based on the conclusions in the Radioactive Substances Committee Thematic Assessment , as these have been demonstrated to have a low potential to result in a significant impact based on the available evidence.  Other pressures filtered out as having low potential for significant impact are disturbance of species from non-renewable energy, land claim and subsea cables; habitat loss from extraction of minerals; anthropogenic sound from aquaculture – marine, offshore structures and subsea cables; marine litter from extraction of oil and gas and offshore structures; nutrients from agriculture and waste water treatment and disposal; input of other forms of energy from coast and flood defence, extraction of oil and gas, land claim, non-renewable energy, tourism and leisure infrastructure, subsea cables, transport – shipping and transport infrastructure; and physical disturbance of the seabed from extraction of oil and gas, non-renewable energy, offshore structures, subsea cables and offshore structures.

The relative ranking of pressures changes when impact is considered (Figure CE.1). Mortality and injury of marine mammals due to fisheries incidental by-catch/entanglement and vessel collisions ranked the highest. Also high-scoring were input of anthropogenic sound from multiple activities (with construction noise (e.g., pile-driving) associated with offshore wind farm development and military operations showing the greatest contribution); and prey depletion associated with fishing activity and disturbance of species from a wide variety of human activities. Input of other substances (chemical contaminants), input of litter and habitat loss from multiple human activities were also shown to be important for marine mammals. The importance of climate change and ocean acidification pressures for marine mammals are described in this thematic assessment. Additionally, the Climate Change Thematic Assessment and Ocean Acidification Other Assessment provide details of the contributing human activities. There is low confidence in the incorporation of these pressures directly into the weighted bow-tie analyses (Figure CE.1a), so these are shown separately in Figure CE.1b.

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 the QSR 2023. 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 also be given to where regional differences may arise by cross-referencing other assessments in the QSR 2023.

The Marine Mammal Thematic Assessment identifies the cumulative pressures for marine mammals (but attempts no regional breakdown of pressures) in terms of both exposure and impact :

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

• Extraction of, or mortality / injury, to wild species from fish and shellfish harvesting; fishing activities; military operations; hunting; aquaculture; extraction of minerals (aggregates); Collision injury / mortality from transport – shipping; renewable energy generation;
• Input of anthropogenic sound from renewable energy generation; military operations; transport – shipping; extraction of oil and gas; aquaculture; non-renewable energy generation (nuclear); offshore structures; subsea cables; transport infrastructure; land claim; coastal defence and flood protection;
• Prey depletion associated with fishing activities;
• Disturbance of species from transport – shipping; renewable energy generation; tourism and leisure activities; extraction of oil and gas; aquaculture; military operations; non-renewable energy generation (nuclear); offshore structures; fishing activities; subsea cables; transport infrastructure; land claim; extraction of minerals (aggregates); coastal defence and flood protection; tourism and leisure infrastructure;
• Input of other substances from waste treatment and disposal; agriculture; transport – shipping; urban uses; industrial uses; extraction of oil and gas; aquaculture; military operations; non-renewable energy generation (nuclear); extraction of minerals (aggregates);
• Input of litter from fish and shellfish harvesting and fishing activities; urban uses; transport – shipping; tourism and leisure activities; industrial uses; extraction of oil and gas; aquaculture; offshore structures; 
• Habitat loss from transport – shipping; fish and shellfish harvesting; offshore structures; fishing activities; extraction of oil and gas; subsea cables; transport infrastructure; renewable energy generation; land claim; extraction of minerals (aggregates); coastal defence and flood protection; tourism and leisure infrastructure; non-renewable energy generation (nuclear);
• Physical disturbance to the seabed from fish and shellfish harvesting; fishing activities; extraction of minerals (aggregates); extraction of oil and gas; transport – shipping; non-renewable energy generation (nuclear); offshore structures; subsea cables; transport infrastructure; land claim; coastal defence and flood protection; tourism and leisure infrastructure;
• Input of other forms of energy from extraction of oil and gas; transport – shipping; non-renewable energy generation (nuclear); offshore structures; subsea cables; transport infrastructure; land claim; coastal defence and flood protection; tourism and leisure infrastructure.
• Input of nutrients from agriculture; waste water treatment and disposal;
• Input of other substances (e.g., radioactive substances);
• Climate change and ocean acidification pressures.

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

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 Greater North Sea (Region II).

Radioactive Substances Committee Thematic Assessment describes:

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

Human Activities Thematic Assessment describes:

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

Regional evidence for trends in the intensity of other human activities or for Climate Change and Ocean Acidification were not available in sufficient detail to be utilised in this assessment.