In the framework of a collaboration between Møreforsking (Dr. Céline Rebours) and the University of Western Brittany (UBO, France), two researchers, Dr. Erwan Ar Gall (Associate professor) and Thomas Burel (PhD student), came to Norway to study the rocky shores near Ålesund. The aim of this work is to define the interaction between seaweeds and their environment. Both diversity and abundance of macroalgal species have been studied on three sites in Hessa and Vigra. Most of species were determined in the field, but when necessary identification was performed using microscopy, in the Møreforsking laboratory. In parallel, grazers were also counted, and the cover of the attached animals was estimated to get an appraisal of the interaction between animals and algae. In order to precisely quantify the effect of hydrodynamics on the populations of seaweed, pressure recorders were attached to the bedrock within seaweed canopies.

Results of this work will be integrated in a European-scale study aiming to determine the effect of latitude on hydrodynamics-seaweed relationships. Similar experimental trials have been conducted in France, Ireland and Spain. The originality of this environmental approach lays on (1) the sampling of macroalgae following bathymetric levels of the shore corresponding to “belts”, and (2) the in-situ determination of wave exposure. The long-term objective of this research program is to develop a predictive model to understand the extent of seaweed covers. This tool could help in estimating the biomass of useful macroalgal species according to various environmental conditions.

The process followed during this experiment is currently used for the implementation of the European framework directories to assess the quality of coastal waters and the ecological state of marine ecosystems.

In the future, it could help in evaluating the impact of human activities on both the macroalgal diversity and the health of exploited seaweed resources in Norway. In this prospect, the partnership between Møreforsking and the University of Western Brittany will be developed.