Semi-Automatic Versus Manual Mapping of Cold-Water Coral Carbonate Mounds Located Offshore Norway

Cold-water coral reefs are hotspots of biological diversity and play an important role as carbonate factories in the global carbon cycle. Reef-building corals can be found in cold oceanic waters around the world. Detailed knowledge on the spatial location and distribution of coral reefs is of importance for spatial management, conservation and science. Carbonate mounds (reefs) are readily identifiable in high-resolution multibeam echosounder data but systematic mapping programs have relied mostly on visual interpretation and manual digitizing so far. Developing more automated methods will help to reduce the time spent on this laborious task and will additionally lead to more objective and reproducible results. In this paper, we present an attempt at testing whether rule-based classification can replace manual mapping when mapping cold-water coral carbonate mounds. To that end, we have estimated and compared the accuracies of manual mapping, pixel-based terrain analysis and object-based image analysis. To verify the mapping results, we created a reference dataset of presence/absence points agreed upon by three mapping experts. There were no statistically significant differences in the overall accuracies of the maps produced by the three approaches. We conclude that semi-automated rule-based methods might be a viable option for mapping carbonate mounds with high spatial detail over large areas.

[1]  P. B. Mortensen,et al.  The deep-water coral Lophelia pertusa in Norwegian waters: distribution and fishery impacts , 2002, Hydrobiologia.

[2]  J. Hall‐Spencer,et al.  In situ observations of fish associated with coral reefs off Ireland , 2011 .

[3]  Jan Helge Fosså,et al.  Trawling damage to Northeast Atlantic ancient coral reefs , 2002, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[4]  D. Wright,et al.  A Benthic Terrain Classification Scheme for American Samoa , 2006 .

[5]  Elvira S. Poloczanska,et al.  Coral Reef Ecosystems under Climate Change and Ocean Acidification , 2017, Front. Mar. Sci..

[6]  Giles M. Foody,et al.  Good practices for estimating area and assessing accuracy of land change , 2014 .

[7]  J. Roberts,et al.  Cold-water corals in a changing ocean , 2014 .

[8]  E. Edinger,et al.  Geological features supporting deep-sea coral habitat in Atlantic Canada , 2011 .

[9]  Peter J. Mitchell,et al.  How good is my map? A tool for semi-automated thematic mapping and spatially explicit confidence assessment , 2018, Environ. Model. Softw..

[10]  A. Wheeler,et al.  Reefs of the Deep: The Biology and Geology of Cold-Water Coral Ecosystems , 2006, Science.

[11]  S. Flögel,et al.  Aggradation and carbonate accumulation of Holocene Norwegian cold‐water coral reefs , 2015 .

[12]  William G. Cochran,et al.  Sampling Techniques, 3rd Edition , 1963 .

[13]  B. J. Todd,et al.  Mapping submarine glacial landforms using acoustic methods , 2016, memoirs.

[14]  Jacquomo Monk,et al.  Quantification of Spatial and Thematic Uncertainty in the Application of Underwater Video for Benthic Habitat Mapping , 2014 .

[15]  Thomas Blaschke,et al.  Geographic Object-Based Image Analysis – Towards a new paradigm , 2014, ISPRS journal of photogrammetry and remote sensing : official publication of the International Society for Photogrammetry and Remote Sensing.

[16]  S. Flögel,et al.  Cold-water coral growth in relation to the hydrography of the Celtic and Nordic European continental margin , 2008 .

[17]  A. Rowden,et al.  Field validation of habitat suitability models for vulnerable marine ecosystems in the South Pacific Ocean: Implications for the use of broad-scale models in fisheries management , 2016 .

[18]  Geoffrey J. Hay,et al.  Geographic Object-Based Image Analysis (GEOBIA): A new name for a new discipline , 2008 .

[19]  T. Thorsnes,et al.  Mapping of Cold-Water Coral Carbonate Mounds Based on Geomorphometric Features: An Object-Based Approach , 2018 .

[20]  Max Kuhn,et al.  Building Predictive Models in R Using the caret Package , 2008 .

[21]  B. Lindberg,et al.  Postglacial carbonate production by cold-water corals on the Norwegian Shelf and their role in the global carbonate budget , 2005 .

[22]  G. Foody.  Thematic map comparison: Evaluating the statistical significance of differences in classification accuracy , 2004 .

[23]  J. Guinan,et al.  Multiscale Terrain Analysis of Multibeam Bathymetry Data for Habitat Mapping on the Continental Slope , 2007 .

[24]  Stephen V. Stehman,et al.  Design and Analysis for Thematic Map Accuracy Assessment: Fundamental Principles , 1998 .

[25]  M. Taviani,et al.  Deep-water scleractinian corals promote higher biodiversity in deep-sea meiofaunal assemblages along continental margins , 2010 .

[26]  S. Cairns,et al.  Will human-induced changes in seawater chemistry alter the distribution of deep-sea scleractinian corals? , 2006 .

[27]  Cold-water coral reefs and glacial landforms from Sula Reef, mid-Norwegian shelf , 2016, memoirs.

[28]  Vonda E. Wareham,et al.  Deep cold‐water corals as nurseries for fish larvae , 2012 .

[29]  D. Yoerger,et al.  Footprint of Deepwater Horizon blowout impact to deep-water coral communities , 2014, Proceedings of the National Academy of Sciences.

[30]  A. Potter,et al.  Can we improve the spatial predictions of seabed sediments? A case study of spatial interpolation of mud content across the southwest Australian margin , 2011 .

[31]  J. Schiewe,et al.  SEGMENTATION OF HIGH-RESOLUTION REMOTELY SENSED DATA - CONCEPTS, APPLICATIONS AND PROBLEMS , 2002 .

[32]  Dawn J. Wright,et al.  Unified Geomorphological Analysis Workflows with Benthic Terrain Modeler , 2018 .

[33]  John Bell,et al.  A review of methods for the assessment of prediction errors in conservation presence/absence models , 1997, Environmental Conservation.

[34]  V. Huvenne,et al.  Using novel acoustic and visual mapping tools to predict the small-scale spatial distribution of live biogenic reef framework in cold-water coral habitats , 2016, Coral Reefs.

[35]  J. Opderbecke,et al.  Morphology and environment of cold-water coral carbonate mounds on the NW European margin , 2007 .

[36]  Jane Elith,et al.  A comparison of resampling methods for remote sensing classification and accuracy assessment , 2018 .

[37]  J. Garrabou,et al.  Upper thermal thresholds of shallow vs. deep populations of the precious Mediterranean red coral Corallium rubrum (L.): Assessing the potential effects of warming in the NW Mediterranean , 2008 .

[38]  Lene Buhl-Mortensen,et al.  Biological structures as a source of habitat heterogeneity and biodiversity on the deep ocean margins , 2010 .

[39]  Zhi Huang,et al.  Predictive mapping of seabed cover types using angular response curves of multibeam backscatter data: Testing different feature analysis approaches , 2013 .

[40]  Veit Hühnerbach,et al.  The Sula Reef Complex, Norwegian shelf , 2002 .

[41]  T. Thorsnes,et al.  Seabed sediments (grain size) of Nordland VI, offshore north Norway , 2017 .

[42]  Brian J. Bett,et al.  Role of cold-water Lophelia pertusa coral reefs as fish habitat in the NE Atlantic , 2005 .

[43]  Rudy J. Kloser,et al.  Impacts of bottom trawling on deep-coral ecosystems of seamounts are long-lasting , 2009 .

[44]  G. Wolff,et al.  Organic matter quality and supply to deep-water coral/mound systems of the NW European Continental Margin , 2007 .