Using novel acoustic and visual mapping tools to predict the small-scale spatial distribution of live biogenic reef framework in cold-water coral habitats

Abstract

Cold-water corals form substantial biogenic habitats on continental shelves and in deep-sea areas with topographic highs, such as banks and seamounts. In the Atlantic, many reef and mound complexes are engineered by Lophelia pertusa, the dominant framework-forming coral. In this study, a variety of mapping approaches were used at a range of scales to map the distribution of both cold-water coral habitats and individual coral colonies at the Mingulay Reef Complex (west Scotland). The new ArcGIS-based British Geological Survey (BGS) seabed mapping toolbox semi-automatically delineated over 500 Lophelia reef 'minimounds' from bathymetry data with 2-m resolution. The morphometric and acoustic characteristics of the minimounds were also automatically quantified and captured using this toolbox. Coral presence data were derived from high-definition remotely operated vehicle (ROV) records and high-resolution microbathymetry collected by a ROVmounted multibeam echosounder. With a resolution of 0.35 9 0.35 m, the microbathymetry covers 0.6 km 2 in the centre of the study area and allowed identification of individual live coral colonies in acoustic data for the first time. Maximum water depth, maximum rugosity, mean rugosity, bathymetric positioning index and maximum current speed were identified as the environmental variables that contributed most to the prediction of live coral presence. These variables were used to create a predictive map of the likelihood of presence of live cold-water coral colonies in the area of the Mingulay Reef Complex covered by the 2-m resolution data set. Predictive maps of live corals across the reef will be especially valuable for future long-term monitoring surveys, including those needed to understand the impacts of global climate change. This is the first study using the newly developed BGS seabed mapping toolbox and an ROV-based microbathymetric grid to explore the environmental variables that control coral growth on cold-water coral reefs.

Climate‐induced changes in the suitable habitat of cold‐water corals and commercially important deep‐sea fishes in the North Atlantic

“…Habitat suitability modelling approaches come with some caveats, and we, therefore, acknowledge multiple common and well-known limitations that may be particularly pronounced when modelling deep-sea taxa. For example, cold-water coral and fish distributions respond to small-scale variation in terrain, such as substrate type and seabed rugosity, as well as local oceanographic conditions such as food availability (Bennecke & Metaxas, 2017;De Clippele et al, 2017;Drazen et al, 2012;Rengstorf et al, 2013;Ross et al, 2015;White et al, 2005). We also recognize some limitations from the quantity, quality and spatial coverage of occurrence data, availability of absence records as well as some uncertainty in deepsea species identification (mostly for cold-water corals Incorporating these needs into the Deep Ocean Observing Strategy can help fill data gaps, and prioritize spatial locations for the collection of key physical and biogeochemical data (Canonico et al, 2019;Levin et al, 2019).…”

Geomorphometric Characterization of Pockmarks by Using a GIS-Based Semi-Automated Toolbox

“…Both marine geoscientists and marine biologists have used BPI widely [10,30]. BPI can be computed using the BTM toolbox [22].…”

“…This result is more successful at highlighting the small pockmarks as well as most of the larger ones, but it also detects artefacts in the MBES data, which are of a similar magnitude to the BPI values within parts of the pockmarks. Both marine geoscientists and marine biologists have used BPI widely [10,30]. BPI can be computed using the BTM toolbox [22].…”

44 Fate of Mediterranean Scleractinian Cold-Water Corals as a Result of Global Climate Change. A Synthesis

“…Zibrowius and Gili 1990;Rogers 1999;Roberts et al 2009;Buhl-Mortensen et al 2010;Mastrototaro et al 2010;Tittensor et al 2010;Gori et al 2013;Smith and Williams 2015); access to more sophisticated deep-sea technology facilitating surveys in deeper water over larger areas (e.g. Hovland et al 2002;Sumida et al 2004;Taviani et al 2005;Wheeler et al 2007;Freiwald et al 2009;Orejas et al 2009;De Mol et al 2011;Gori et al 2013;Savini et al 2014;Clippele et al 2016; see also Angeletti et al, this volume; Lo Iacono et al, this volume), and in several regions, primarily due to fishing activity and fisheries research surveys where the bycatch of deep-sea corals has occurred (e.g. Fosså et al 2002;Gass and Willison 2005;Hourigan 2009;Tracey et al 2011;Clark et al 2015).…”