Compiling preliminary SEEA Ecosystem Accounts for the OSPAR regional sea: experimental findings and lessons learned

Ecosystem Accounting provides a framework to measure and value relationships amongst ecosystems, society and the economy. The accounts measure ecosystem extent, condition and services, providing the means to identify and internalise ecological degradation, as well as understanding the risks and dependencies of economic activities on the environment and tracking progress towards sustainable development. The OSPAR Convention, which concerns the protection of the Marine Environment for the North-East Atlantic, has committed to accounting for natural capital and ecosystem services, where the UN System of Environmental Economic Accounting – Ecosystem Accounting (SEEA EA) provides an international accounting standard for guidance in compiling accounts. Here, we describe the first attempt in compiling accounts aligned with SEEA EA at a Regional Sea scale. We: (i) identified existing open access data, (ii) produced accounts for selected ecosystems and valued their services and asset value and (iii) identified challenges and lessons learned. For ecosystem services, we measured fish provisioning, carbon sequestration and outdoor recreation from coastal and marine environments across OSPAR contracting parties. The exercise identified lack of fitting data at regional level, spatially-explicit linkages and harmonisation need to be overcome to further expand


Introduction
The last century has seen the widespread loss and degradation of ocean ecosystems, driven in part by undervaluing their importance to society and the economy within decisionmaking.Globally, ocean ecosystems are amongst the most productive systems, providing goods and services that underpin the health, well-being and livelihoods of millions of people (IPBES 2019).Valuing their contribution, however, has been difficult to measure, where many services and benefits arise from the existence of ecosystems and their support of economic and human activities is not reliant on direct extraction or use (e.g.climate regulation, coastal protection, fish nurseries etc.) (United Nations et al. 2021).The failure to account for such contributions has led to the prioritisation of economic values to the detriment of ocean ecosystems.
In response, holistic and integrated measures towards sustainable ocean development have been embedded within strategic plans and policy instruments at international (European Commission's Sustainable Blue Economy Agenda* , High Level Panel for a Sustainable Ocean Economy* ), regional (North-East Atlantic Environment Strategy* ,The Baltic Sea Action Plan* ) and national (e.g.Fiji Ocean policy* , Portugal National Ocean Strategy* ) levels.These plans and policies support integrated assessments of the ocean environment framed through the concepts of 'natural capital' and 'ecosystem services' (Ruijs et al. 2018).Natural capital can be defined as the ecosystems and natural resources that supply the ecosystem goods and services that benefit society and the economy (European Environment Agency 2019).The measurement and monetary valuation of ecosystem services supports the conservation of ocean ecosystems by recognising that the majority of ecosystem services are difficult or impossible to replace (European Commission 2020, Maes et al. 2020).Measuring ecosystem services in a coherent and transparent manner, however, requires standardisation, which could be, in part, achieved through definitions and classifications contained within statistical accounting frameworks.
Countries have long maintained 'national accounts' to measure aspects of the economy (e.g.Gross Domestic Product, GDP), where most countries follow the internationally agreed UN standard System of National Accounts (SNA).The SNA, however, has long been criticised for poorly accounting for natural capital, where its depletion usually leads to a short-term increase in measures of economic growth, such as GDP (Helm 2015).The need to go 'Beyond GDP' has led to the development of the UN System of Environmental Economic Accounting (SEEA), as a complementary standard with concepts and definitions aligned to the SNA, to better recognise nature's contributions to economic output and to advance sustainability within decision-making (Dasgupta 2021).The SEEA provides guidance towards accounts that contain regular and objective data (European Environment Agency 2019) that is coherent and internationally comparable in line with the UN Fundamental Principles of Official Statistics.* The SEEA is composed of the Central Framework (SEEA CF) and Ecosystem Accounting (SEEA EA, henceforth 'Ecosystem Accounts').The SEEA CF concerns accounting for thematic stocks and flows (e.g.energy, water and economy-wide material flow accounts), while the Ecosystem Accounts extend accounting into the spatial domain, to measure ecosystems and related flows to society and the economy.Ecosystem Accounts consider the extent and condition of ecosystems by type (e.g.seagrass, saltmarsh) and how condition may impact the ecosystem services provided (Edens and Hein 2013).Global, regional and national initiatives* have driven the uptake of the SEEA and is now being implemented in more than 90 countries.To date, 41 countries have compiled Ecosystem Accounts (UNSD 2023).However, most Ecosystem Accounts focus on the terrestrial environment and significant challenges remain to produce accounts for marine and coastal areas (Buonocore et al. 2020, Manea et al. 2019, Townsend et al. 2018).
Countries have developed thematic accounts concerning the measurement of the ocean economy (e.While accounting aligned with the SEEA is performed predominantly at the national scale or sub-national level, the transboundary nature of multiple resources and human pressures and impacts on the ocean necessitates a regional approach to management.Regional Seas Conventions, such as OSPAR, assist in coordinating the actions of Contracting Parties to address challenges, such as habitat loss and degradation, invasive species and poor water quality (Maes et al. 2020, Veretennikov 2019).Within OSPAR, environmental status is tracked by indicators reported within the so-called Quality Status Report (QSR) (OSPAR 2000, OSPAR 2010b), which also identifies the priority actions to achieve OSPAR and the Contracting Parties vision of a healthy, biologically diverse and sustainably-used sea.*The compilation of Ecosystem Accounts at a regional seas scale could assist in tracking environmental status and producing indicators (e.g.land use or extent change, climate-related indicators, changes on ecosystem services -both physical and monetary -, asset value changes or indicators concerning the flows of benefits and costs).Compiling preliminary SEEA Ecosystem Accounts for the OSPAR regional sea: ...
The compilation of a preliminary and experimental set of Ecosystem Accounts for the OSPAR area was performed to identify the data available for accounting and the gaps and limitations that require further efforts and coordination to address.This paper describes the process to compile Ecosystem Accounts for the OSPAR area, presenting the first version of the accounts for the whole OSPAR region and first attempt of marine ecosystem accounts for a regional sea.We provide an overview of: (i) the methods used to compile the Ecosystem Accounts, (ii) preliminary results* and (iii) a discussion of limitations, lessons learned and recommendations for improvement.The work provides a blueprint and foundation for other regional seas to begin compiling Ecosystem Accounts.

Study area: OSPAR and the North-East Atlantic Ocean
The A map of the OSPAR Maritime Area, denoting sub-regions I to V, as defined by the OSPAR convention.Ecosystem Accounting was performed by seafloor type (A3 -A6), according to EUNIS classifications.A map of ecosystem types, further disaggregated, is provided in Suppl.material 1.

Overview of SEEA Ecosystem Accounts standard
The Ecosystem Accounts are composed of several linked accounts that contain values in either physical (e.g.tonnes) or monetary terms (Fig. 2).The accounts measure either stocks (ecosystem extent, condition and asset accounts) or flows (ecosystem services) amongst ecosystems, society and the economy (i.e.users -industry, government and households).
• Ecosystem extent accounts measure the area per ecosystem type within an accounting area.The Convention on Biological Diversity (CBD 2003) defines ecosystems as a "dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit".The Ecosystem Accounts framework followed.The figure illustrates the set of accounts forming the accounting system, in which the accounts are strongly interconnected and provide a comprehensive and consistent view of the ecosystems.Note that Ecosystem Condition accounts were not compiled.Within Fig. 2, accounts are numbered to demonstrate the flow of data, where later accounts are dependent on the compilation of the preceding account.For instance, an estimation of the supply of ecosystem services is dependent on ecosystem extent and condition.

Compilation and assessment of available ecosystems and services data at the OSPAR level
Ecosystem Accounts information presented in this paper was collected for the OSPAR Maritime area,* which includes internal and territorial waters of OSPAR Contracting Parties and adjacent high seas.The compilation of ecosystem extent accounts, service (supply and use) and asset accounts for the OSPAR area accounts was produced by applying guidance from the Ecosystem Accounts standard (United Nations et al. 2021) and the GOAP technical guidance (GOAP 2020).
The methodology for the account compilation was determined through an assessment of existing Ecosystem Accounts, informal consultations with technical experts and through the OSPAR Intersessional Correspondence group on Economic and Social Analyses (ICG ESA).The Ecosystem Accounts of this study were recorded by: • Conducting a literature review of existing marine ecosystem accounts and inventory of relevant open-source data; • Defining Ecosystem Accounting components, including identification and selection of ecosystems and their services based on data availability; • Assessing and compiling available data on ecosystems and services at the OSPAR level and assessing feasibility of accounts; • Compilation of ecosystem extent accounts, service (supply and use) and asset accounts for the OSPAR area.
Experiences on ecosystem accounts were drawn from several countries, reviewed in Lange et al. ( 2022) and Gacutan et al. (2022).*A workshop on 'Marine Natural Capital Accounts' was hosted by OSPAR,* consisting of more than 60 participants from across the world, with expertise in economics, official statistics, environmental science and policy.
The workshop consisted of interactive sessions exploring data availability and gaps, challenges and policy applications of accounting (see Suppl.material 3).
A literature review was conducted and data inventory compiled (see Table 5 Suppl.material 2).Data availability and evidence gaps were determined through the OSPAR Data & Information Management System (ODIMS) database, which contains extensive timeseries of periodic monitoring of the chemical and ecological status of the North-East Atlantic Ocean* and other publicly available datasets.The full list of data sources used in the analyses are provided in Suppl.material 2 (Table 5).In assessing the inventory of data, a preliminary accounting snapshot of the OSPAR region was produced, containing data published between 2008 and 2019.
The inventory identified ecosystem extent and their services as feasible for account compilation, based on the literature review findings.However, key data gaps between linking ecosystems to their condition spatially prevented the compilation of ecosystem condition accounts.
The Ecosystem Accounts provides a "Reference List" of ecosystems services, structured into three broad categories: provisioning, regulating and maintenance and cultural services (United Nations et al. 2021).In this study, relevant ecosystem services were selected, based on OSPAR priorities and data availability (

Ecosystem type and extent account
The accounting treatment of marine and coastal assets is different to land-based environmental assets.Marine ecosystems are not concentrated near a single surface (e.g.land or water interface), but extend throughout the water column and seabed, which serve as natural boundaries for ecosystem types.Depicting ecosystem types vertically as three- Compiling preliminary SEEA Ecosystem Accounts for the OSPAR regional sea: ... dimensional, however, poses numerous challenges to accounting and, therefore, this study used a two-dimensional (2-D) approach to characterise the seabed in the study area.
The Ecosystem Accounts endorse the use of the IUCN Global Ecosystem Typology (GET), although existing datasets for the OSPAR area were not aligned with GET classifications.This paper employs surface-based delineation which aligned with the methods of marine accounts for the UK (Thornton et al. 2019).The study uses the European Nature Information System (EUNIS),* which is a hierarchical classification that defines habitats from broad scales to species-specific scales.The seafloor types considered were infralittoral (A3) and circalittoral rock (A4), sublittoral sediments (A5) and deep-sea sedimentary habitats (A6).
Data for ecosystem extent were sourced from EUSeaMap (2019),* which is hosted and maintained by the European Marine Observation and Data Network (EMODnet).The EUSeaMap 2019 covers most EUNIS Marine Habitats (A3 -A6), although it lacks littoral biotic habitats (A1) and sediments (A2).Estimated extent for key intertidal ecosystems and coastal estuaries (A2) were extracted from extent accounts produced by the European Environment Agency.*The intersection between EUSeaMap and the OSPAR area was extracted using regional boundaries within ODIMS, to extract the extent of EUNIS habitats.Spatial analyses and manipulation were performed using ArcMap (v.10.4,ESRI).

Ecosystem condition account
A condition account for the OSPAR area would provide several metrics of the state and functioning of specific ecosystem types.An ideal starting point is from existing indicators produced by OSPAR for measuring the ecosystem status or pressures.Some of these relevant indicators compiled by OSPAR are also aligned with the GOAP technical guidance and consistent with the Ecosystem Accounts framework (OSPAR 2010a, OSPAR 2010b) (see Suppl.material 1).Amongst these metrics are acidity, eutrophication, species diversity, sea surface temperature, coral condition, seagrass cover, fish stocks state or grade of minerals (GOAP 2020).
Several of these indicators have already been estimated and compiled by OSPAR in the various Quality Status Reports (OSPAR 2010b).However, the indicators are currently reported as aggregates at the OSPAR level (i.e.entire North-East Atlantic) and its regions (see Fig. 1), preventing them from being disaggregated spatially, to enable attribution to specific ecosystems types (such as those assessed in the ecosystem extent account).

Ecosystem services physical supply and use accounts
Ecosystem services measured in physical terms (i.e.physical flow accounts) record the supply of ecosystem services and the beneficiaries or users (economic units including households, businesses and governments) of those services per ecosystem.
The 'use' of ecosystem services identifies the first direct 'users'; industries, government and households, which further relates to their 'dependency' on ecosystem services ( Further details on methodology and data to estimate each ecosystem service in physical terms are provided in Suppl.material 2. The main challenges faced during data compilation and accounting include the following (with further exploration in Suppl.material 2): 1. Fish provisioning was calculated, based on landings reported through the UN Food and Agricultural Organization (FAO), which may not report all species of commercially-caught fish provisioned by the ecosystems.Further, landing could not be spatially assigned to specific ecosystems; 2.
Estimates for carbon sequestration omitted seagrass, which are important carbon sinks (Bedulli et al. 2020).Consequently, carbon sequestration included in this report is underestimated within the region; 3.
Estimates of outdoor recreation were based on the results of the KIP-INCA project, which used potential visits to coastal recreational areas per year (daily use) to account for this service.As the values could not be applied to the entire OSPAR area, they serve as a preliminary estimate of the service for the North-East Atlantic.

Ecosystem services monetary supply and use accounts
In the context of ecosystem accounting, the valuation of ecosystem services in monetary terms is commonly performed by multiplying the values measured within the physical accounts with the 'exchange' value of individual ecosystem service prices (United Nations et al. 2021).For the present accounts, valuations were based on benefit transfer (Table 1), which is defined by Richardson et al. (2015) as "the transfer of original ecosystem service value estimates from an existing 'study site' or multiple study sites to an unstudied 'policy site' with similar characteristics that is being evaluated which is the extrapolation and adaptation of benefits from one study location to another one".While primary valuation for each context is ideal and provides a more reliable range of estimates, studies at the regional sea scale are often unfeasible due to time and resource constraints (Brander 2013).Compiling preliminary SEEA Ecosystem Accounts for the OSPAR regional sea: ... Benefit transfer of resource rent unit* from the UK marine natural capital accounts was applied to the provisioning service of wild aquatic animals estimated within this study; and the results from resource rent study in the Norwegian Aquaculture Industry were applied to the provisioning service of animals or products from aquaculture.For carbon sequestration, the efficient carbon price from the low reduction scenario calculated by Horlings et al.
(2020a) was used.Finally, for outdoor recreation, the monetary accounts from the INCA project were used (only including the values for OSPAR Contracting Parties).

Ecosystem asset account
The value of an ecosystem asset can be determined by calculating the net present value (NPV) of the expected future flows of income associated with the different ecosystem services (Schenau et al. 2019, United Nations et al. 2021).The utilisation of an NPV approach suggests that the value of an ecosystem asset is tied to its ability to provide ecosystem services, as well as how this ability is projected to evolve over time.

Ecosystem type and extent account
The preliminary Extent accounts covered more than 9.2 million km and approximately 68% of the OSPAR area ( habitats were the most extensive ecosystem, at 46% of the accounting area.In contrast, infra-and circalittoral rocky habitats only accounted for 0.006% (5281 km ) of the OSPAR area.*As seabed data were from data sources aggregated across multiple years, extent accounts for multiple years (and thus changes) could not be compiled.

Ecosystem services accounts
Ecosystem Service accounts were compiled for the period 2008 to 2019 (Table 3).For physical values, fish provisioning was estimated between 2012 and 2019, while data for provisioning from aquaculture were estimated between 2012 and 2015.Estimated flows for carbon sequestration and capture were only available for 2019, while outdoor recreation could only be estimated for 2012.(2018).Disaggregation to lower EUNIS levels is provided in Suppl.material 1.
Marine Ecosystem Service supply account for the OSPAR area in physical and monetary values, between 2012 and 2019.Empty cells denote unavailable data.
Compiling preliminary SEEA Ecosystem Accounts for the OSPAR regional sea: ... The accounts revealed that fish provisioning fluctuated between 8.1 and 9.3 Mt, peaking in 2018 (9.32 Mt), while lowest in 2019 at ~ 8.1 Mt.The monetary value estimated for fish provisioning, however, ranged between €1.7 billion and €2.8 billion, with no clear relationship between physical and monetary values.Provisioning services to aquaculture were stable between 2012 and 2015 in physical terms, ranging between 2.12 and 2.15 Mt, although monetary value increased from €1.3 to €3.7 billion in the same period.
Marine carbon sequestration and capture was valued at €1.6 million in 2019, calculated using coastal saltmarshes from littoral habitats (A2) and sublittoral sand and mud (A5).Crucial habitats could not be included so these estimates omit significant carbon sinks within shelf seas, thus representing a gross underestimation for the value of carbon sequestration of the OSPAR area (see Suppl.material 2).Outdoor recreation services were estimated for coastal areas and was estimated at €253 million in 2012 for OSPAR Contracting Parties that were EU Member States (EU-28), excluding Finland due to lack of data (Table 4).

Ecosystem asset account
The monetary value of each ecosystem asset was estimated by calculating the NPV using initial estimates of ecosystem services from this study (see Suppl.material 2).The total asset value for the OSPAR region was €125.75 billion, of which more than 40% comes from carbon sequestration and outdoor recreation.The asset value estimated for carbon sequestration was €48.15 billion and for outdoor recreation €7.56 billion.As both carbon sequestration and outdoor recreation services were underestimated, monetary estimates for the assets are also underestimated.*

Discussion
This paper presented the initial Ecosystem Accounts for the OSPAR region, compiling accounts of ecosystem extent, the supply and use of their services and a preliminary assessment of their asset value, aligned with the SEEA EA standard.As far as we are aware, this work represents the first compilation of Ecosystem Accounts for a Regional Sea.The accounts were compiled from available data, providing a 'snapshot' of stocks (extent, asset value), while measurement of ecosystem service flows varied in the accounting years presented.The approach to account for the different ecosystem services are experimental (in that they are not defined in any international standard), yet it establishes the groundwork and foundation for future Ecosystem Accounting practices.The following discussion will explore each of the Ecosystem Accounts compiled, limitations and future research needs.The discussion concludes with recommendations to facilitate the compilation of OSPAR accounts into the future.

Extent accounting for the OSPAR area
The OSPAR region has abundant and centralised data, relative to Regional Seas.
The study used the EUSeaMap 2019, which harmonised multiple datasets across various years to produce a seabed classification that covered approximately 68% of the OSPAR area.The seabed map used the EUNIS classification, aggregated to six broad ecosystem types, which was previously used to produce the national accounts for the United Kingdom, within the OSPAR area (see Grilli et al. (2022), Thornton et al. ( 2019)).The EUNIS employed classification system, however, aligns more with abiotic seabed classifications, Compiling preliminary SEEA Ecosystem Accounts for the OSPAR regional sea: ... rather than the ecosystem types, differing from international ecosystem classifications, such as the IUCN Global Ecosystem Typology framework (Keith et al. 2020).Further, the EUSeaMap 2019 does not cover the land-sea interface, which omitted coastal and intertidal habitats (i.e.A1 and A2), which required additional data sourced through the European Environmental Agency Ecosystem Accounts.Future accounts should consider using datasets aligned with international ecosystem classifications and enable analyses of changes to extent over time (Townsend et al. 2018).

Ecosystem Service measurement and evaluation
While there is a large amount of literature on specific ecosystem services within the OSPAR region, few employ a regional approach and are compatible with SEEA Ecosystem Accounting (i.e.linked to specific ecosystems).The initial estimation of ecosystem services provided for the North-East Atlantic was determined through logic chains, where ecosystem services were linked to specific EUNIS classifications, drawing from existing logic chains from the UK marine accounts (Thornton et al. 2019).The use of these logic chains are aligned with the SEEA Ecosystem Accounting standard (United Nations et al. 2021) and have previously been used to compile accounts for the Netherlands (Statistics Netherlands and WUR 2021).These logic chains were used to compile ecosystem service estimates for wild-catch fisheries, aquaculture, carbon sequestration and outdoor recreation, in physical and monetary terms.Greater specificity at the regional level, in linking towards specific economic sectors, requires further collection of coherent and standardised data within the OSPAR region.
The study also performed a preliminary valuation of ecosystem services in monetary terms, recognising that the methods for valuation of specific services are controversial and most useful when analysing changes over time, rather than absolute values (Droste and Bartkowski 2017).Estimated changes to stocks and flows in monetary terms could highlight the importance of non-use and non-market ecosystem services (see Comte et al. (2022)), to quantify the benefits of sustainable ecosystem management in decision-making (Hein et al. 2020).
Due to data limitations, several estimates relied on benefit transfer and Grammatikopoulou et al. ( 2023) explore uses-cases of the technique to develop accounts when capacity or resources are limited.In general, benefit transfer is used because it combines ease of use and minimal data needs (Office for National Statistics 2021, United Nations et al. 2021), where its use is expected to increase with resource constraints for accounting activities (Johnston et al. 2015).While a primary valuation study is preferred when feasible (Johnston et al. 2015), benefit transfer provides a means to compile preliminary ecosystem accounts, for iteration as data become available (Brander 2013).

Fish provisioning
In this study, benefit transfer of resource rent unit was implemented to value the provision of fish and aquaculture products.Further research, however, is needed to identify the valuation techniques that better relate physical and monetary values as resource rent may produce low or negative monetary estimates of the flows from ecosystem services to the national economy (Obst et al. 2015).The study identified a disconnection between benefit transfer of resource rent and unit of fish provisioning in this work.Lower fish provisioning in 2016 was valued higher (8.33 Mt landed, valued at at 2,846 mill.€), while higher fish provisioning in 2015 had lower monetary value (9.15 Mt landed, valued at 1,728 mill.€), which contrasted with the results from other years (Table 3).We would expect, then, more fish provisioned or used would be translated in less amount of the service in monetary terms.A challenge with the valuation method is separating the value of human and produced capital with the ecosystem service of food provisioning, as resource rent is linked to fuel prices.Changes to fuel price has implications for the valuation of the ecosystem service, which does not reflect the state and trend of the underlying quality or health of the ecosystem.

Carbon sequestration
Estimates of carbon sequestration in physical and monetary terms revealed preliminary estimates for the OSPAR area.The service was valued in 2019 to be more than half of the value of fish provisioning in 2018, indicating the significance of the service.Carbon price was used to value the service, where Horlings et al. (2020a) discussed the advantages and disadvantages between the use of the social cost of carbon and carbon price of policy targets.The use of carbon price may be beneficial in providing advantages, including lower uncertainty and greater viability (see Horlings et al. (2020a)).Further studies are needed to identify the impact of the valuation methods, noting the importance of relative change against absolute values, as the former provides key information on the state of natural capital and ecosystem assets.

Outdoor recreation
Measuring outdoor recreation services was a challenge due to data harmonisation, rather than data limitations, as reporting practices for recreation-and tourism-related activities varied significantly amongst OSPAR countries.The estimates within this study were low, relative to other ecosystem service assessments (Vysna et al. 2021), which could be linked to the omission of countries and the weak distinction between coastal and marine recreation and the use of "Potential visits".The dataset used contained only EU members, which omitted Norway, Iceland and Switzerland OSPAR Contracting Parties (Vallecillo Rodriguez et al. 2018).Further, the SEEA Ecosystem Accounting makes a distinction between "capacity" and "actual visits" as an indicator for use, which contrasts with "Potential visits" used within the study (Vallecillo Rodriguez et al. 2018, Vallecillo et al. 2019).

Recommendations and future work
The process of developing Ecosystem Accounts for the North-East Atlantic has produced several illustrative lessons in accounting for Regional Seas.The main challenges faced during the Ecosystem Accounting process suggests that future accounting and data activities should: (i) align with international ecosystem and ecosystem services classifications; and (ii) condition data and indicators should be spatially disaggregated to ecosystems (c.f.aggregated across ecosystems).To better align OSPAR reporting with Ecosystem Accounting and enable compilation of a condition account, data collection and reporting could shift from a region-based to an ecosystem-based approach.As a Regional Sea, the OSPAR could assist in the standardisation and harmonisation of data collection and reporting methods for monitoring on ecosystem condition, enabling Ecosystem Accounting, while meeting the other objectives of the OSPAR mandate.This could be performed through OSPAR's ODIMS data platform, which contains relevant data for accounting.
Further  2022)).The accounts could also explore the assets and services contained within the water column (i.e.vertical stratification) to understand flows across three-dimensions to improve decision-making concerning dynamic stocks, such as fisheries (Findlay et al. 2022).

Conclusions
This study presented the initial Ecosystem Accounts for the OSPAR region, advancing trans-boundary Ecosystem Accounting at the Regional Seas level.Specifically, the accounts provide an understanding of the state and trend of the marine environment, contributing to OSPAR's mission of monitoring the health and conservation of marine habitats.The compilation of accounts for ecosystem extent, services and asset value, aligned with the SEEA EA standard, provides a 'snapshot' of stocks and flows and suggests processes to compile accounts as a foundation for future ecosystem accounting practices.While the accounting approach for specific ecosystem services remains experimental, implementation through initiation estimates highlighted the need for further efforts in data collection, harmonisation and refinement of classifications to improve the accuracy and spatial scope of future accounts.The findings underscore the importance of considering relative monetary values rather than absolute numbers, as they provide key insights into the state of ecosystems and impacts to the supply of services.
Several recommendations have been identified to enhance the future compilation of OSPAR Ecosystem Accounts.Firstly, a shift towards ecosystem type-based data collection would enable more direct links between condition indicators and specific ecosystem types, improving the accuracy of the accounts.The harmonisation of data amongst OSPAR Contracting Parties is crucial, requiring the development of common methodologies and tools to facilitate data sharing and standardisation.The ODIMS platform presents an 42 opportunity for OSPAR to streamline the collection and collation of diverse data sources.
Additionally, systematic and coherent data collection and recording practices should be established to enable the periodic production of accounts, facilitating the comparison and tracking of changes in ecosystems and their services over time.These recommendations, when implemented, will further enhance the relevance and usefulness of Ecosystem Accounts in providing information for policy decisions and promoting sustainable ecosystem management in the OSPAR region and beyond.
As leading OSPAR countries in recording Ecosystem Accounts, guidance on technical considerations were drawn from The Netherlands (de Jongh et al. 2021, Schenau et al. 2019) and UK (Grilli et al. 2022, Office for National Statistics 2021, Thornton et al. 2019) to estimate the different accounts.
Table1), including: (i) provision of wild aquatic animals and animals or products from aquaculture due to the importance of this economic activity in the area, (ii) climate regulation through carbon sequestration and capture since OSPAR Commission is looking for ways to reduce the negative effects of climate change and (iii) outdoor recreation due to its social importance in the area.

Table 25
The first direct users were identified following the main users and beneficiaries included in the initial logic chains* for selected ecosystem services provided by SEEA EA.The government is considered as a direct user and beneficiary of carbon sequestration because the service benefits society as a whole(Horlings et al. 2020b).For OSPAR, 'government' refers to the collective of OSPAR Contracting Parties, as they all benefit from this non-exclusive service.For outdoor public recreation, values were drawn from the KIP INCA* project for EU Members States that were also OSPAR Contracting Parties.The project used potential visits to coastal recreational areas per year (daily use) as a proxy for the possibility for citizens to enjoy nature within daily activities(Vallecillo Rodriguez et al.  2018)and is recorded under 'households'.*Themarinenaturalcapital accounts published by the Netherlands and UK are used as the main guidance since they are the accounts available when the research was conducted within the North-East Atlantic zone(de Jongh et al. 2021, Office for National Statistics 2021  , Schenau et al. 2019, Statistics Netherlands and WUR 2021, Thornton et al. 2019).

Table 2
).Of the area with data coverage, deep-sea sedimentary

Table 1 .
Ecosystem services assessed within this study and their relevance to Ecosystem Accounts(GOAP  2020, United Nations et al. 2021).Methods and sources used to calculate the monetary accounts are also included.Definitions drawn from CICES (Haines-Young and Potschin 2017).

Table 2 .
Marine ecosystem extent accounts for the OSPAR area by EUNIS classification.Data were sourced from manipulation of the EUSeaMap (2019) and European Environmental Agency Ecosystem Accounts

Table 4 .
Marine Ecosystem Service use accounts for the OSPAR area in physical and monetary values.Empty cells denote unavailable data.