Krause-Jensen, Dorte3; Marbà, N.2; Alcoverro, T.2; Birk, S.2; Duarte, C. M.2; Pedersen, A.2; Neto, J. M.2; Orfanidis, S.2; Garmendia, J. M.2; Muxika, I.2; Borja, A.2; Dencheva, K.2
1 Department of Bioscience - Marine Ecology, Department of Bioscience, Science and Technology, Aarhus University2 unknown3 Department of Bioscience - Marine Ecology, Department of Bioscience, Science and Technology, Aarhus University
Seagrasses are key components of coastal marine ecosystems and many monitoring programs worldwide assess seagrass health and apply seagrasses as indicators of environmental status. This study aims at identifying the diversity and characteristics of seagrass indicators in use within and across European ecoregions in order to provide an overview of seagrass monitoring effort in Europe. Through a compilation we identified 49 seagrass indicators representing 42 monitoring programs and including a total of 51 seagrass metrics used either alone or in various combinations of up to 14 metrics per indicator. The seagrass metrics represented 6 broad categories covering different seagrass organizational levels and spatial scales. The large diversity is particularly striking considering that the pan-European Water Framework Directive sets common demands for the presence and abundance of seagrasses and related disturbance-sensitive species across Europe, and the diversity of indicators reduces the possibility to provide pan-European overviews of the status of seagrass ecosystems. The diversity can be partially justified by differences in species and associated time scales of responses as well as by differences in habitat conditions and associated community types but also seems to be determined by tradition. We encourage an evaluation of seagrass indicators on the basis of their responses to pressures in space and time and their associated uncertainty in order to identify the most suitable indicators for specific European regions.