Publication providing elaborated guidance how to assess sea-floor integrity under the MSFD

doi:10.2760/8315684

Most EU countries have in the meanwhile reported on the marine benthic habitat quality status under the MSFD, taking into consideration the guidance on Article 8 assessment* in development and discussed in the Technical Group Seabed**. Although the assessment guidance with regards to sea-floor integrity will continue to be developed the coming years, now an interim overview has been published. It provides the current status of guidance with more elaborated information, examples and ways of handling data, use of indicators and the first agreed threshold values.

RAICEVICH, S., KORPINEN, S., SCHROEDER, A., WIJNHOVEN, S., DINESEN, G.E. et al., Assessment of sea-floor integrity under the EU Marine Strategy Framework Directive – Supplementary information to the Article 8 assessment guidance, ALONSO ALLER, E. and VIGHI, M. (editors), Publications Office of the European Union, Luxembourg, 2025, https://data.europa.eu/doi/10.2760/8315684, JRC142314.

The report provides supplementary information to the Article 8 assessment guidance document (European Commission, 2022) where:

  • the physical pressures impacting the sea-floor and benthic habitats are defined,
  • human activities causing such pressures are discussed,
  • elements to be assessed are identified,
  • assessment scales and marine reporting units are proposed,
  • inter-relations with other MSFD criteria and other policies are identified and integration with them suggested,
  • the agreed threshold values are presented, and
  • approaches to address uncertainty are discussed.

TG Seabed has agreed on the general principles of the assessment of sea-floor and benthic habitats, such as pressure definitions, definition of adverse effects and necessary thresholds indicating good status. With these general principles, the coherence of the Member States assessments under Descriptor 6 will improve, and it is anticipated that many details will likely become clearer once good practices have accumulated from the upcoming assessments.

This report has been updated to integrate the latest developments under TG Seabed until December 2023, and thus includes references to the D6C4 and D6C5 threshold values proposed by TG Seabed and adopted by MSCG on 15 March 2023 and endorsed by Marine Directors on 4 June 2023.

* The assessment of the sea-floor and benthic habitats of Europe’s seas is a requirement of the EU Marine Strategy Framework Directive (MSFD) under the qualitative descriptor 6 (“Sea-floor integrity is at a level that ensures that the structure and functions of the ecosystems are safeguarded and benthic ecosystems, in particular, are not adversely affected”). Article 8 of the MSFD requires this assessment, while Commission Decision 848/2017 lays down the criteria and methodological standards for such an assessment. The guidance document #19 for the MSFD implementation provides an overview of the assessments under Article 8 for all the qualitative descriptors, while this report aims to give a more elaborated guidance for Descriptor 6.

**TG Seabed is the ‘technical group on seabed habitats and sea-floor integrity’ established by the Member States and the European Commission under the MSFD Common Implementation Strategy.

Ciliate communities on macrofauna: There is a world to discover.

First description of epizoic ciliates on Bathyporeia including undescribed species.

Hardly visible with the naked eye, flourishing communities of epibiont species are often present on macrofauna. Examining Bathyporeia (small crustaceans of few millimeters in size, abundantly present in marine and estuarine waters) from Dutch waters showed that peritrich ciliates were present on 44% of the over 3500 specimens investigated. Although known for a range of other species including crustaceans, peritrich ciliates on Bathyporeia, when present also often abundantly present, were not described in detail before. Only d’Udekem d’Acoz (2004) mentions the common presence of ramified colonies of peritrich ciliates on appendages of Bathyporeia in his paper on the genus.

We discovered several types including solitary and colony-forming specimens, of which the most common species appeared to be Zoothamnium nanum (an epibiont species known from other small crustaceans like Gamarus species). However, also a likely sofar undescribed species of the genus Epistylis appeared to be common, and another type of Zoothamnium (that might be an undescribed species) was observed.

Findings on infestation patterns for different Bathyporeia species for different waterbodies and years and possible implications for basibionts (hosts) and epibionts are presented and discussed in a paper published in Crustaceana: Wijnhoven et al. (2018). Taking into account the common presence and large abundances on a variety of macrofauna species, indicates that epizoic ciliates might play a more important role in ecosystem functioning than is now recognized and/or understood. There is still a whole world to discover!

Photographs of peritrich ciliates on Bathyporeia sp.; a) Typical colonies of peritrich ciliates (most likely Zoothamnium nanum) attached to a peduncle of an antenna from Bathyporeia pilosa (specimen stained with Rose Bengal and preserved in formaldehyde) (1000x magnification); b) Typical colonies of peritrich ciliates (most likely Zoothamnium nanum) in detail (on a specimen stained with Rose Bengal and preserved in formaldehyde) (4000x magnification); c) Individual and small colonies of alive Zoothamnium sp. on peduncles from antenna 2 of an alive specimen of Bathyporeia sarsi (1000x magnification); d) A singular alive specimen of Zoothamnium nanum on Bathyporeia sarsi (4000x magnification) with its cilia out; e) Singular alive peritrich ciliates on Bathyporeia pilosa (4000x magnification) showing a specimen without a spasmoneme (Epistylis sp.); f) Singular and couples of peritrich ciliates on Bathyporeia pilosa (4000x magnification) where the lower specimen belonging to the genus Zoothamnium lacks transverse folds (Zoothamnium sp.).

Wijnhoven, S., Zwiep, K.L., Hummel, H. (2018). First description of epizoic ciliates (Sessilida Stein, 1933) on Bathyporeia Lindström, 1855 (Peracarida, Amphipoda) and infestation patterns in brackish and marine waters. Crustaceana 91(2),133-152.

Other study cited:

d’Udekem d’Acoz, C. (2004). The genus Bathyporeia Lindström, 1855, in western Europe (Crustacea: Amphipoda: Pontoporeiidae). Zool. Verh. Leiden 348, 3-162.

Geographic patterns of biodiversity in European coastal marine benthos

Trends with latitude are primarily indirect and so can be overcome by local variation of environmental factors.

This is the conclusion of a recent study investigating geographic patterns in European coastal marine macrobenthic communities, based on a pan-European harmonized monitoring by EMBOS partners (European Marine Biodiversity Observatory System). Latitudinal trends and regional differences in diversity and densities appear to be merely the result of particular sets and ranges of environmental factors and location characteristics specific to certain areas. The diversity and densities of benthos were mostly positively correlated with environmental factors such as temperature, salinity, mud and organic matter content in sediment, or wave height, and related with location characteristics such as system type (lagoons, estuaries, open coast) or stratum (intertidal, subtidal).

The study with ‘Ecoauthor involvement‘ is published online in the Journal of the Marine Biological Association of the UK and available since september 14th, 2016. You can contact me for more information by using the contact form.

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Lugworm burrows in the Oosterschelde

Lugworm burrows in the Oosterschelde

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Salinity as a barrier for ship hull-related dispersal of bivalves

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This gallery contains 2 photos.

‘Important long-term experimental data on the survival of invasive dreissenid and mytilid species under various salinity conditions’ were there waiting on the shelf for years. But now they have been published in Marine Biology (Mar Biol 163:147) and give amongst … Continue reading