Habitat quality assessment


Genetic variation is part of habitat quality in the following ways:

1. Many Baltic Sea habitats are formed in part by one or more habitat-forming species and the genetic variation of the habitat forming species will affect habitat quality.

2. Many Baltic Sea species are subdivided into populations. A local population is more easily lost if it is genetically adapted to its environment and is genetically distinct from other populations of the species. Loss of a common species or a key species will affect the habitat quality.


Baltic intertidal and subtidal seaweeds and seagrasses provide important habitats for crustaceans, molluscs, fish larvae, ephemere algae and many other groups of species. Clonal richness (genotype diversity) increases variation in tolerance to extreme stress and in tolerance to grazing in Fucus radicans.




Seagrass medows formed by the eelgrass, Zostera marina, also resist extreme climate stress better if the meadow consist of many genetically different clones rather than one or a few clones. Furthermore, meadows with high clonal richness produce more biomass and host more associated fauna than meadows with low clonal richness.



List of relevant scientific publications here:


Genetic concerns in water quality assessment 

The threat posed by alien species and alien genotypes towards biodiversity is calling for the need to assess and monitor the genetic status of marine species. How is this issue handled in the EU Directives?

The EU ‘Water Framework Directive’ does not address the topic explicitly. In the ‘Common implementation strategy’ though, formulated by the European Commission as a guiding document for how to implement the Directive, alien species is identified as one variable to consider when determining water quality. Given that the term ‘species’ is somewhat ambiguous, concerning whether the genetic level is included or not, the formulation opens for different interpretations.

The EU ‘Marine Strategy Framework Directive, however, explicitly emphasise the importance to take genetic concerns into account when working with water quality assessment. The Directive specifies that the distribution of non-indigenous species or, where relevant, genetically distinct forms of native species should be one variable in the analysis of current environmental status. Thus, according to the Marine Directive water quality assessment should include genetic analyses.  


Assessing genetic quality of habitats

Genetic data is needed that describes the population genetic structure of the habitat-forming species or other key species of great importance to the ecosystem. If such data is not available, it is urgent to get this done and the best approach is collaboration with a relevant research institute. (There is to our knowledge currently no private consultancy companies that perform genetic assessments of natural species.)

If genetic data is available, there may be a need to contact experts in population genetics or evolutionary ecology to interpret the data. Most likely the genetic data will not be generated for the area of concern but for the target species but from other areas. With such information at hand, it may be possible to infere the genetic quality of the habitat. However, the best approach is to have information from the particular habitat (populations) of concern.



Kerstin Johannesson, University of Gothenburg, Sweden

Responsible editor: Kerstin Johannesson, University of Gothenburg, Sweden 
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