Biodiversity as a marine valuation concept
At a workshop in Belgium consderation was given to developing criteria for valuing the marine environment. This article considers the extent to which biodiversity can be used in the evaluation process. It is part of a summary of the discussions held during a workshop on marine biological valuation, held from 6 to 8 December 2006 at Ghent (Belgium). The workshop was a joint venture of the EU CA ENCORA (http://www.encora.org) and the EU NoE MARBEF (http://www.marbef.org). 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. The workshop report can be downloaded at (http://www.marbef.org/documents/Theme3/GhentWS/report.pdf)
- 1 Biodiversity: A valid valuation criterion?
- 2 Argument for not including 'biodiversity' as a criterion in our valuation concept
- 3 How to include 'biodiversity' in our valuation concept
- 4 Which elements of biodiversity from the framework should be included in the valuation concept?
- 5 Notes
- 6 See also
- 7 References
Biodiversity: A valid valuation criterion?
When valuing marine areas, it is important to capture as many attributes of biodiversity as possible, since biological structures and processes exist on different organizational levels (viz. genes, species, population, community and ecosystem). This is also captured in the definition of biodiversity set at the Convention on Biological Diversity.
According to Roberts et al. (2003a), valuable marine areas should be characterized by high biodiversity and properly functioning ecological processes which support that diversity. According to many authors the biodiversity of an area is simply a function of the species diversity, but we believe that a valuation framework that incorporates as many organizational levels of biodiversity as possible is far preferable.
Although the concept of biodiversity as a valuation criterion is highly attractive to managers, the practice of distilling biodiversity to a single index or a few dimensions is unjustified, which is why biodiversity was not used as a criterion in our valuation concept.
Argument for not including 'biodiversity' as a criterion in our valuation concept
Biodiversity is still integrated in the concept, but in a different way. Yet, because of its frequent use, we feel that a critical literature review and an argumentation for not including biodiversity as a valuation criterion in our concept are needed.
In most research studies only the species richness of a subzone is assessed, but biodiversity manifests itself on many more levels of organization (from the genetic to the ecosystem); simply counting the number of species in a subzone as a measure of biodiversity can be misleading because subzones with a high species richness do not necessarily exhibit a high diversity on other levels.
Species richness of birds
- For example, Ray (1999) used species richness of birds as a surrogate for overall biodiversity, an approach which is based on the fact that birds have dispersed to and diversified in all regions of the world. Yet, analyses revealed that species richness hotspots of birds coincided poorly with those of other biota.
- Hotspots of species richness, endemism or rarity are often less discernible in continuous marine ecosystems than in terrestrial environments. Turpie et al. (2000) used the hotspot approach for species richness (and weighting all species equally) and did not achieve good representation for coastal fish species. Thus, the hotspot approach based on species richness alone is not a useful starting point for the selection of biological valuable marine areas. This was also noted by Breeze (2004), who found the traditional hotspot approach to be narrowly defined and species-focused, while the criteria used for identification of highly valuable marine areas should be much broader.
- The use of focal species (indicators, umbrellas, flagship species), which has been developed mainly from a terrestrial viewpoint, is not straightforward to apply in the marine environment. Since connectivity is very different in the marine environment, the concept of a particular species indicating a certain size of intact habitat is not readily applicable.
- Ward et al. (1999) also investigated the use of surrogates for overall biodiversity, and found that habitat types suited this function best.
The concept of ‘benthic complexity’ was introduced by Ardron et al. (2002) as a proxy for benthic species diversity. The authors assume that the bathymetric (topological) complexity of an area is a measure of benthic habitat complexity, which in turn would represent benthic species diversity. However, the data needed to perform the spatial variance analyses needed to quantify ‘benthic complexity’ are usually lacking.
Because detailed data on the diversity of species or communities are often scarce or nonexistent, Airamé et al. (2003) proposed to assess the habitat diversity as a proxy for overall biodiversity, because data on habitat distributions are generally available or can be constructed.
How to include 'biodiversity' in our valuation concept
We feel that a more general framework for the assessment of biodiversity is needed, that this framework should use available information from a range of organizational levels (genes, species, communities, ecosystems), and that the relationships among these levels need to be examined.
It is also emphasized that, in addition to biodiversity ‘structures’, there is also a need to include biodiversity processes such as aspects of the functioning of ecosystems, which could even be more important than high species richness or diversity indices in certain low biodiversity sites like estuaries. Bengtsson (1998) stated that biodiversity is an abstract aggregated property of species in the context of communities or ecosystems, and that there is no mechanistic relationship between single measures of biodiversity and the functioning of the entire ecosystem. Ecosystem functioning can, however, be included indirectly in an assessment of biodiversity value, through the identification of functional species or groups and critical areas.
Zacharias & Roff (2000) visualised the various components of biodiversity (see Fig. 1) in their ‘marine ecological framework’ (going from the species to the ecosystem level and including both biodiversity structures and processes). Each of these components can be linked to one or more of the selected valuation criteria, which makes it unnecessary to include biodiversity as a separate valuation criterion. The genetic level was included in this framework during the workshop and this resulted in the table on the right.
By using this ‘framework’ it could therefore be possible to apply the valuation criteria while integrating various components of biodiversity.
Which elements of biodiversity from the framework should be included in the valuation concept?
Framework of Zacharias & Roff (2000)
The table from Zacharias & Roff (2000) (see Fig. 1.) was used to produce the assessment questions that are described in the protocol. During the workshop these elements of biodiversity were closely analyzed to see whether some assessment questions were missing or redundant.
- If all elements from the table are considered in the valuation process we are rather valuating ‘biodiversity’ than ‘biology’ and the term should be changed in ‘marine biodiversity valuation’.
- As many elements from the table as possible should be added to the protocol in the form of assessment questions, depending on the confidence level of the available data to assess them.
- As there are still only very fragmentary data available for the genetic level it is suggested to exclude these elements (for the moment) from the protocol.
- Subareas within the study area can have different levels of available data and not all biodiversity assessment questions can be assessed for each subarea. This could give difficulties when we want to compare the values of the subareas (as they are based on different amounts of assessment questions). Some solutions could be:
- Only compare the subareas with the same amount of information
- If extrapolation to neighboring subareas is possible, comparison of subareas can be done, indicating that the confidence level diminishes for each subsequent extrapolation.
- Include all the information for each subarea and, depending on the degree of confidence on the scores of the subarea for each assessment question, decide whether to add the scores or not. This could lead to subareas without an indication of the total value (= subareas with a low degree of confidence).
- The table of Zacharias and Roff (2000) was screened and only the relevant elements for valuation were selected (see Fig. 2.).
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  for the full citation and to download a copy of the paper.
- Biodiversity of sandy beaches - Dr. Lech Kotwicki
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