Environmental Variability Index (EVI) - a MAREANO methods study for guidance of sampling effort

Abstract

MAREANO is an interdisiplinary programme mapping Norwegian offshore bathymetry, geology, biology and geochemistry. Following bathymetric mapping by the Norwegian Hydrographic Service, biological and geological sampling are undertaken by the Institute of Marine Research (IMR) and the Geological Survey of Norway (NGU) to obtain visual (video) and physical sample data that are used in conjunction with bathymetric and backscatter data for the generation of thematic maps. Currently MAREANO samples 10 video lines pr. 1000 km2 in the Norwegian Sea and 5 video lines per 1000 km2 in the eastern part of the Norwegian Barents Sea. As the environmental and spatial variability of the Norwegian seabed has become better known, the need for a more flexible strategy has become apparent. In order to optimise MAREANO sampling effort there is a need for a sampling strategy that takes into account the level of envrionmental and spatial variability, i.e. increasing sampling effort in heterogeneous areas and decreasing effort in homogeneous areas. In a response to this need for flexibility the development of an Environmental Variability Index (EVI) was initiated by MAREANO. The purpose of the EVI is to provide a basis for scaling the sampling effort to environmental and spatial variability.