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This article forms part of discussions centred around valuing the marine environment at a workshop held from 6 to 8 December 2006 at Ghent (Belgium). The workshop was a joint venture of the EU CA ENCORA ( and the EU NoE MARBEF ( Both Theme 7 within ENCORA and Theme 3 within MARBEF deal with marine/coastal biological valuation and the workshop aimed to reach a consensus on this topic. It specifically considers the definition and use of 'naturalness' in the evaluation process.


The ‘naturalness’ criterion is defined[1] as the degree to which an area is pristine and characterized by native species (i.e. absence of perturbation by human activities and absence of introduced or cultured species).[2][3][4][5][6]

According to the EC Habitats Directive (1992), the criterion ‘naturalness’ is indirectly included in site selection, as several criteria need to be applied to ‘natural habitats’: these are defined as ‘(land or) water zones with special geographic, abiotic and biotic characteristics which can be either totally natural or semi-natural (as described in Annex I of the Directive)’.

Application of the criterion

The problem with assessing this criterion is the fact that it is often unknown what the natural state of an area should be. Many assumptions may be made, but more studies are needed to help define what ‘natural’ really is. There are also hardly any completely natural areas left anymore and it is difficult to assess the degree of naturalness in areas at great depth or in areas of poor accessibility.

So, in order to assess the naturalness of a subzone, there is a need for comparison to appropriate pristine areas or reference sites.

If such areas do not exist, an alternative way to assess naturalness is to use information on native/introduced or cultured species in the study area, which can be seen as proxies for the degree of naturalness.

Another approach to assess the naturalness of a subzone is to look at the health or composition of the inhabiting communities/species. For instance, healthy, natural benthic communities are in many cases characterized by a high biomass (dominated by long-lived species) and a high species richness.[7] Deviations from this pattern, resulting in a reduced macrobenthic biomass and a species richness dominated by opportunistic species, could be assigned to a certain level of stress and could be used to index the naturalness of a subzone. Such health indices, however, still require some reference to a baseline level of naturalness.

Lacking even this information, one could use data on the location and intensity of human activities. The environmental and ecological state of subzones which are characterized by the absence of human disturbance can be used as a rough index of the degree of naturalness.

Naturalness should not only consider the degree of disturbance to attributes of species, but also to functional processes of the marine ecosystem.


These paragraphs are based on the paper of Derous et al. (2007). A concept for biological valuation in the marine environment . Oceanologia 49 (1). See FLANDERS MARINE INSTITUTE web site at [1] for further information and to download a copy of the paper.


  1. Derous S., Agardy T., Hillewaert H., Hostens K., Jamieson G., Lieberknecht L., Mees J., Moulaert I., Olenin S., Paelinckx D., Rabaut M., Rachor E., Roff J., Stienen E.W.M., van der Wal J.T., Van Lancker V., Verfaillie E., Vincx M., Weslawski J.M., Degraer S. (2007). A concept for biological valuation in the marine environment. Oceanologia 49 (1).
  2. DFO (2004). Identification of ecologically and biologically significant areas. DFO Can. Sci. Adv. Sec. Ecosystem Status Report 2004/006.
  3. Department for Environment, food and Rural Affairs (2002). Safeguarding our seas. A strategy for the conservation and sustainable development of our marine environment. Defra, London.
  4. Connor et al. (2002)
  5. JNCC (2004). Developing the concept of an ecologically coherent network of OSPAR marine protected areas. Joint Nature Conservation Committee Paper 04 N08.
  6. Laffoley D.d'A., Connnor D.W., Tasker M.L., Bines T. (2000b). Nationally important seascapes, habitats and species. A recommended approach to their identification, conservation and protection. English Nature Research Paper No 392.
  7. Dauer D.M. (1993). Biological criteria, environmental health and estuarine macrobenthic community structure. Marine Pollution Bulletin 26, 249-257.