Valuation and assessment of biodiversity

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This article summarizes knowledge and practices in Europe on the valuation of coastal and marine biodiversity. Through the concept of Biological Valuation and Biological Valuation Maps (BVM) that can be used as baseline maps for future spatial planning at sea, practical guidelines for incorporating biodiversity in coastal and marine policies are provided.


Biodiversity is an all-inclusive term to describe the total variation among living organisms of our planet. In its most simple form, biodiversity or biological diversity is therefore 'Life on Earth' and marine biodiversity is 'Life in the Seas and Oceans’. While genetic, species and ecosystem diversity can be considered as elements of ‘structural diversity’, ‘functional diversity’ refers to the variety of biological processes, functions or characteristics of a particular ecosystem. There are several ways in which ecological classifications group organisms according to common functions: classification according to their habitat, to their position in the food web or to their functional feeding mechanism. The Coastal Wiki provides the most commonly used measurements of biodiversity (species richness, evenness and taxonomic indices) and sampling tools (both for pelagic and benthic organisms) of marine biodiversity.


Other Coastal Wiki articles related to marine biodiversity are listed in the category Marine biodiversity.

National and international strategies for the biological valuation

The continuously increasing socio-economic pressure on the coastal system urges the need for a decision-making framework to objectively allocate the different user functions in the coastal zone. The coastal biodiversity suffers badly from the anthropogenic stress hampering the urgent need for a thorough preservation and restoration of coastal biodiversity. A strategy is needed to provide an integrated view on nature’s intrinsic value. Biological value is here defined as the value of biodiversity, without any reference to anthropogenic use. As such, the biological value complements the social and economic valuation. Till now, when requested, the biological value of an area was basically assessed through an unguided procedure, primarily based upon a (the available) best expert judgement. A marine biological valuation strategy, in contrary, should ideally be (1) scientifically widely acceptable, to avoid an uncontrolled proliferation of valuation strategies (i.e. broad scientific support), and (2) widely applicable, to maximise its applicability (e.g. stakeholder involvement). In order to support such a strategy, Biological Valuation Maps (BVM) can be used as baseline maps for future spatial planning at sea. BVM compile and summarize all available biological and ecological information for a study area and allocate an overall biological value to subzones

Concept of biological valuation

There is worldwide recognition of the benefits of management for sustainable use and conservation of the sea. In order to develop management strategies in the marine environment, reliable and meaningful integrated ecological information is needed. Biological valuation assessments have been developed primarily for terrestrial systems and species. Problems encountered when applying terrestrial-based assessments to marine areas were demonstrated in the difficulties encountered implementing the EC Habitats Directive (92/43/EEC) in the marine environment. The Directive was written from a terrestrial viewpoint, and applying it to more dynamic marine systems has proved problematic. Criteria developed for identifying terrestrial species and habitats for conservation cannot be easily applied to the marine environment; different valuation criteria are needed for marine areas. Therefore, the European Commission has developed a Marine Strategy Directive, which recognizes the need for a thematic strategy for the protection and conservation of the European marine environment with the overall aim to promote sustainable use of the seas and conserve marine ecosystems. The definition of the value of marine areas has to be based on the assessment of areas against a set of objectively chosen ecological criteria, making best use of scientific monitoring and survey data. A first step towards such an objective valuation framework was made in the Netherlands, where selection criteria from the EC Habitat and Bird Directives and the OSPAR guidelines were used to determine which marine areas have special ecological values in terms of high biodiversity. A scientifically sound and widely applicable concept for marine biological valuation, drawing on existing valuation criteria and methods and attempts to rationalize them into a single model was performed [1]. This concept represents a consensus reached by a large and diverse group of experts in the field.

The valuation criteria that were selected for this concept are rarity, fitness consequences, aggregation (as first-order criteria), naturalness and proportional importance (as modifying criteria). Once the concept of biological valuation is applied to a marine study area, the result of this process could be visualized on marine biological valuation maps (BVMs). Marine BVMs can act as a kind of baseline describing the intrinsic biological and ecological value of subzones within a study area. They can be considered as warning systems for marine managers who are planning new, threatening activities at sea, and can help to indicate conflicts between human uses and a subzone’s high biological value during spatial planning.

Adaptation of the Concept[2]

During a workshop the concept and protocol of marine biological valuation was discussed, which resulted in fine-tuning the concept of marine biological valuation, especially with respect to its applicability to marine areas. The concept of marine biological valuation was reorganized to avoid double counting of scores (i.e. lumped criterion ‘aggregation-fitness consequences’) and to allow a more logical order of the steps which should be made during valuation (i.e. assessing the biological value on two different scales instead of incorporation of ‘proportional importance’ as a valuation criterion). ‘Rarity’ was retained as a valuation criterion while ‘naturalness’ was excluded from the concept. ‘Naturalness’ is usually assessed on the basis of the absence of human impacts in the subzone. This makes it almost impossible to apply this criterion without specific reference to human impacts, which is deliberately excluded from the definition of biological valuation.

Development Protocol (tools)[3]

Guidelines for a generic biological valuation protocol based on the above mentioned valuation criteria has been set up and tested on a European scale. The steps in the valuation protocol are described below. They encompass the selection of the valuation criteria for the determination of the appropriate assessment questions, the practical algorithms to evaluate the criteria and the final scoring of all assessment questions:

  • Selection of valuation criteria at two different scales, first at the local (study area) scale and secondly at a broader, (eco)regional scale.
  • Subdivision of the study area in subzones. For the purpose of marine biological valuation a division of the study area in subzones according to a habitat classification seems most appropriate.
  • Available data and reliability of information. A detailed database, covering all data and information used for the value assessment, should be attached to the maps, and this should be consulted whenever the maps are used to guide advice or when used as a warning system in management decisions.
  • Assessment questions. By answering a set of possible assessment questions, related to the different structures and processes of biodiversity and coupled to the proposed valuation criteria, all aspects linked to biological and ecological valuation are visualized
  • Mathematical algorithms. By developing specific algorithms for each assessment question the value of the subzones can be quantitatively assessed relatively to each other.
  • Scoring. It seems impossible to set uniform thresholds which would be applicable to all marine ecosystems, so this needs to be done on a case by case basis. When all relevant questions are scored for the different subzones within a study area, all criteria (with respect to all organizational levels of biodiversity) are assessed.
  • The results of the biological valuation of a study area can now be presented on a map, where each subzone within the area is assigned a colour corresponding with its value [4].

A major benefit of the proposed marine biological valuation protocol is the fact that all available biological and ecological data are integrated for each subzone, which makes the comparison between subzones easier for the users of the Biological Valuation Maps. The reliability of the assessed intrinsic value should be noted by attaching a label to the different subzones. This label can display the amount and quality of the data used to assess the value of a certain subzone or it can display how many assessment questions could be answered given the data available for each subzone (reliability of information). These reliability labels should be consulted simultaneously while using the BVMs. Next to that, they help to identify knowledge gaps which could direct future scientific research.

Threats to biodiversity

Four main treats to marine biodiversity are: Eutrophication, Fisheries, Invasions and the Effects of Global Climate Change.


In the EEA report State of Europe's seas [5] an overview is given of the most important physical, biological and exploitation characteristics, the main threats to biodiversity and the policies at work (nature protection and protection of marine resources by restrictions on fishing and hunting).

Related articles

Multifunctionality and Valuation in coastal zones: concepts, approaches, tools and case studies
Multifunctionality and Valuation in coastal zones: introduction
Values of amenities in coastal zones
Socio-economic evaluation
Marine biological valuation maps - an example from Belgium


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  4. Derous, S. 2008. Marine biological valuation as a decision support tool for marine management. Thesis Gent University
  5. EEA 2015. State of Europe's seas. Report No 2/2015, ISBN 978-92-9213-859-2, doi:10.2800/0466, 216 pp