Mapping of eelgrass (Zostera marina) in Møre og Romsdal in 2015 and 2016

Summary

Mapping of eelgrass (Zostera marina) was conducted by NIVA in 2015 (funded by the Norwegian Environment Agency) and 2016 (County Governor of Møre og Romsdal). In 2015 the Romsdalsfjord system and Vigra in the Nordøyane area were given priority, in 2016 the “Green corridor” (Grønn corridor, Søre Sunnmøre), the Borgundfjord system and the Ellingsfjord system was given priority. Our field work was conducted 6-10. October 2015 and 20-14. September 2016 using water binoculars in the shallow areas and an underwater camera from a boat in the deeper areas. Field mapping, delineation of eelgrass meadows and valuation was conducted according to the standard of the National program for mapping biodiversity – coast (Rinde 2008, Bekkby et al. 2012). In 2015 we identified both small isolated meadows (the smallest one was 4 m2) and large meadows (150 000 m2). 13 of the meadows got the value A, 14 got the value B and 17 got the value C. The deepest observed point of seagrass growth (regardless of density, height or patchiness) varied between 1.2 and 8.8 (standardized to the lowest astronomical tide level). In 2016 we identified in total 79 eelgrass meadows. The larges one was 24 000 m2, the smallest one was only 8.5 m2. The deepest observed point of seagrass growth varied between 0.6 and 7 m. None of the meadows got A (national) value, seven got B (regional) value and 72 got C (local) value. The National program has not finished identifying the cod spawning areas. As a consequence, the values of the meadows may change when this information is updated.