Cold-Water Coral Habitat Mapping: Trends and Developments in Acquisition and Processing Methods

Aaron Lim,Luis Conti,Andrew J Wheeler

doi:10.3390/geosciences11010009

Abstract

Cold-water coral (CWC) habitats are considered important centers of biodiversity in the deep sea, acting as spawning grounds and feeding area for many fish and invertebrates. Given their occurrence in remote parts of the planet, research on CWC habitats has largely been derived from remotely-sensed marine spatial data. However, with ever-developing marine data acquisition and processing methods and non-ubiquitous nature of infrastructure, many studies are completed in isolation resulting in large inconsistencies. Here, we present a concise review of marine remotely-sensed spatial raster data acquisition and processing methods in CWC habitats to highlight trends and knowledge gaps. Sixty-three studies that acquire and process marine spatial raster data since the year 2000 were reviewed, noting regional geographic location, data types (‘acquired data’) and how the data were analyzed (‘processing methods’). Results show that global efforts are not uniform with most studies concentrating in the NE Atlantic. Although side scan sonar was a popular mapping method between 2002 and 2012, since then, research has focused on the use of multibeam echosounder and photogrammetric methods. Despite advances in terrestrial mapping with machine learning, it is clear that manual processing methods are largely favored in marine mapping. On a broader scale, with large-scale mapping programs (INFOMAR, Mareano, Seabed2030), results from this review can help identify where more urgent research efforts can be concentrated for CWC habitats and other vulnerable marine ecosystems.

Highlights

It is estimated that less than 5% of the seafloor is mapped at a resolution comparable to similar studies on land [1]
We present a perspective on the future needs for mapping Cold-water coral (CWC) habitats which are relevant to other marine environments
The criteria for studies to be included: (a) are peer-reviewed publications of CWC reef or mound habitats; (b) published no earlier than the year 2000 to highlight recent developments; (c) should present the acquisition and processing of spatial, georeferenced raster data that have been used as a primary dataset in the study and; (d) processing methods should not include point observations derived from video or physical samples

Summary

Introduction

It is estimated that less than 5% of the seafloor is mapped at a resolution comparable to similar studies on land [1]. Several recent studies have highlighted the environmental importance of CWC habitats as biodiversity hotspots because they develop complex local and regional food chains, serving as important spawning, nursery, and feeding areas for a multitude of fishes and invertebrates [15,16,17,18] They support speciose, high-biomass ecosystems at water depths where life is otherwise relatively scarce [5,19]. It is evident that there are large knowledge gaps which need to be filled by further mapping and integrated, multidisciplinary, and multi-scale research including integrated modeling of distribution, geology, biology, ecology, and the assessment of human impact [20] Given their occurrence in deep, inaccessible parts of the planet, the most common way of understanding these habitats is through marine remote sensing and subsequent analyses. We present a perspective on the future needs for mapping CWC habitats which are relevant to other marine environments

Future Mapping Perspectives

Surveying Cold-Water Coral Habitats

Processing Methods

Findings

Concluding Remarks