Mapping EMUs (Ecological Marine Units): The creation of a global GIS of distinct marine environments to support marine spatial planning, management and conservation

A steering committee formed under the auspices of the intergovernmental Group on Earth Observations (GEO; http://www.earthobservations.org/geoss.php) met at the offices of ESRI in Redlands CA on 25-27 February to progress the development of a global map of ecological marine units (EMUs). This work builds upon an earlier terrestrial classification and map (Sayre et al., 2014) of ecological land units (ELUs; http://www.aag.org/cs/global_ecosystems). At this inception meeting our goals were to explore concepts of a coupled pelagic and benthic classification (Costello, 2009) and review existing classification schemes as well as build a unique, 3-dimensional GIS of relevant existing data sets with which to map EMUs.

The committee endorsed an approach that encompasses classifications of the seafloor and water column as separate but interlinked domains at a spatial resolution of 1 km2. It was agreed that the classification should be based mainly on physical data. For the seabed, key classifying variables are depth, seabed slope, geomorphology (Harris et al., 2014), bottom water temperature, dissolved oxygen, particulate organic carbon flux, solar irradiance, carbonate chemistry and bottom current regime. The committee adopted 9 horizontal benthic zones: 1. coastal; shelf (2. low, 3. medium and 4. high relief); 5. slope; abyssal (6. plains, 7. hills and 8. mountains); and 9. hadal. For the pelagic zone, key classifying variables from available data sets (Davies and Guinotte, 2011) are depth, temperature, salinity, dissolved oxygen, primary production, particulate organic carbon flux, carbonate chemistry, solar radiance, water clarity (k490), surface currents, wave regime, tidal range and sea ice cover. The committee adopted 15 water column volumes divided into surface, epipelagic, mesopelagic and deep pelagic where they intersect the 9 benthic horizontal zones. One application of the EMUs is as a standardized partitioning of marine space and abiotic characteristics to understand and predict biotic distributions using species distribution data (for example). Plans are to produce a draft map of EMUs by the end of 2015.