Nordic intercalibration of hard bottom macroalgae monitoring methodologies


image of Nordic intercalibration of hard bottom macroalgae monitoring methodologies

The aim of the ALGONOMY project was to harmonise Nordic macroalgae monitoring methodologies and to agree on common metrics that without extensive cost could be implemented in the national monitoring programmes. This report gives a description of the macroalgae monitoring methods used in Finland, Sweden, Denmark, and Norway and of the two common metrics "total algal cover" and "lower depth limit of macroalgal species" that was implemented to intercalibrate between the Nordic countries. Total cover estimates were significantly related to water clarity and provides a good ecological indicator for assessing the effects of nutrient management. Lower depth distribution limit is a good metric for classification but is set by more factors than water quality. In general, there is a need for better coordination between macroalgae and water quality monitoring with regard to geographic distance and sampling frequency to reflect processes and relationships.



Discussion and Conclusions

Total cover estimations were most uncertain for Askö and also Finnish archipelago, because total cover had to be normalised to the fraction of suitable substrate at these study sites. The most precise depth-specific estimate of total cover is obtained from averaging over 10 camera samples, as carried out on the Swedish west coast.


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