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Nordic intercalibration of hard bottom macroalgae monitoring methodologies

Algamony

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.

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Results

A total of 245 cover observations were obtained from the southern Finnish archipelago coast, representing 7 areas (Brännskär, Bålaskär, Granbusken, Pitkäluoto, Ryssholm, Västrä Källskär, and Ämmärukka, figure 4.1) and 7 years (1996, 1998, 2001, 2002, 2003. 2005, and 2007). Data were collected in the months of June-August. Cover estimates were provided for macroalgae (not normalised to suitable substrate), rock, boulder, stone, gravel and sand. Cover estimates were normalised to the total cover of suitable substrate, where it was assumed that rock, boulder and stone all comprised 100% suitable substrate, gravel comprised 50% suitable substrate, and sand was not considered a suitable substrate. Most observations had suitable substrate close to 100%.

English

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