The workshop on scoping of physical pressure layers causing loss of benthic habitats D6C1– methods to operational data products (WKBEDLOSS) is part of a stepwise process to delivering advice on sea-floor integrity for the Marine Strategy Framework Directive (MSFD). In collaboration with its strategic partners, the high level objectives undertaken by ICES within the project were: 1) to identify benthic physical disturbance pressure layers available within ICES and the European and wider marine community across the four EU (MSFD) regions – including the mapping of pertinent data flows and the establishment of criteria needed to ensure the practical use of the data in assessing benthic impact – in the workshop WKBEDPRES1 (ICES HQ 24–26 October 2018); 2) to identify physical pressure layers causing loss of benthic habitats across the four EU regions, including mapping of data flow and establish guidance to ensure the practical use of the data in assessing benthic impact - in the workshop WKBEDLOSS (ICES HQ 11–13 March 2019); 3) to collate physical pressure layer data causing loss or disturbance (October 2018–Aug 2019), using identified sources and targeted data calls; and 4) to evaluate and operationally test the application of compiled physical pressure layer data causing loss or disturbance (WKBEDPRES2, 30 September–2 October 2019).
WKBEDLOSS focused on objective 2, the requirement of MSFD GES Commission Decision (EU) 2017/848 criterion D6C1 to assess the spatial extent and distribution of physical pressure layers causing loss of benthic habitats, within each ecoregion and subdivision. Where information on activities was missing, or where the data collected was not suitable for this task, data require-ments were highlighted by workshop participants. The process necessitated input from many sources, bringing together research science, marine spatial planning, management experts and indicator developers, all components required for the delivery of MSFD. The resultant collated information needs to be appropriate for the assessment of benthic habitats (D1) and seafloor in-tegrity (D6C3-C5) as set out in the Commission Decision.
WKBEDLOSS defined physical loss as any human-induced permanent alteration of the physical habitat from which recovery is impossible without further intervention.
Alteration of the physical habitat refers to a change in the EUNIS level 2 habitat type. Loss can be given as extent in square kilometres, or percentage loss per EUNIS level 2 habitat. Human interventions facilitating recovery (e.g. removal of man-made structures from the seabed, restor-ing the original substrate by depositing materials or re-introducing species in the case of loss of biogenic habitat) refer to actions allowing the physical habitat to return to its original EUNIS level 2 habitat type.
WKBEDLOSS distinguished between three types of physical loss: sealed physical loss, un-sealed physical loss and the loss of biogenic habitat. Sealed loss, in general, arises where structures or substrates have been introduced which in and of themselves change the physical habitat. Un-sealed loss results from changes in physical habitat due to alterations in physical habitat resulting from an activity or activities and from the indirect effects of placement of man-made structures. This distinction is necessary as data flows recording physical loss differ according to these types.
WKBEDLOSS identified and listed the anthropogenic activities (physical pressure layers) caus-ing physical loss by region. Activities were grouped into those resulting in sealed loss (introduc-tion of structures or substrates) and those potentially resulting in unsealed loss. For some activities, the physical loss may be only a part of the licensed zone for the activity. Unsealed loss-causing activities seldom cover the entire licensed extent of the activity (e.g. ag-gregate extraction). Likewise, sealed physical loss may cover only a proportion of a li-censed zone (e.g. wind turbines within the entire wind farm area).
Physical loss can be mapped based on the actual footprint of an individual structure (i.e. sealed loss). Around these structures, a buffer zone (area of potential impact that extends beyond the footprint) can apply to both loss (e.g. scouring leading to change of EUNIS level 2 habitat type) and disturbance (e.g. scouring not leading to change of EUNIS level 2 habitat type). Hence, map-ping unsealed loss requires further qualification following the compilation of activity data to ascertain if loss has occurred.
Assessing sealed and unsealed physical loss comprises five generic steps: (1) to identify the MSFD-competent authorities who may hold or have access to suitable physical loss data, (2) to request spatial data and attribute information for each physical loss-causing activity, (3) to assess the surface area of physical loss, (4) to assess and document the level of confidence for each fea-ture in the attribute table, and (5) to manage data according to the FAIR principles.
To distinguish unsealed physical loss from physical disturbance, unsealed loss requires further qualification (i.e. in situ observation of habitat change) following the compilation of activ-ity/pressure data to ascertain if loss rather than disturbance has occurred. Data provisioning to determine if loss has occurred may either become part of the operating obligation for the licensed activity or, a targeted monitoring approach may be adopted. In situations where limited moni-toring hampers ascertaining changes in EUNIS level 2 habitats, the severity of the activity on the habitat may be modelled and used to infer loss, though such approaches should be supported by clear scientific validation. Data requirements for unsealed loss are similar to those noted in WKBEDPRES1.
Assessing the loss of biogenic habitat comprises three steps: (1) to identify the present and his-toric biogenic habitat-forming species, (2) to assess the natural spatial distribution and extent of the biogenic habitat and (3) to assess the loss of biogenic habitat. Note that in case of historical (poor geographically referenced) loss, the historic extent baseline can be estimated based on e.g. regional reviews or habitat suitability mapping.
During the data collection phase, it is important to identify a level of confidence in the positional and spatial accuracy of the data.