Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning

Subtidal natural hard substrates (SNHS) promote occupancy by rich benthic communities that provide irreplaceable and fundamental ecosystem functions, representing a global priority target for nature conservation and recognised in most European environmental legislation. However, scientifically valid...

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Autores principales: Giacomo Montereale Gavazzi, Danae Athena Kapasakali, Francis Kerchof, Samuel Deleu, Steven Degraer, Vera Van Lancker
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Lenguaje:EN
Publicado: MDPI AG 2021
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Acceso en línea:https://doaj.org/article/7eeba4cab24d4a92baa376940c1fe3c9
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spelling oai:doaj.org-article:7eeba4cab24d4a92baa376940c1fe3c92021-11-25T18:54:42ZSubtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning10.3390/rs132246082072-4292https://doaj.org/article/7eeba4cab24d4a92baa376940c1fe3c92021-11-01T00:00:00Zhttps://www.mdpi.com/2072-4292/13/22/4608https://doaj.org/toc/2072-4292Subtidal natural hard substrates (SNHS) promote occupancy by rich benthic communities that provide irreplaceable and fundamental ecosystem functions, representing a global priority target for nature conservation and recognised in most European environmental legislation. However, scientifically validated methodologies for their quantitative spatial demarcation, including information on species occupancy and fine-scale environmental drivers (e.g., the effect of stone size on colonisation) are rare. This is, however, crucial information for sound ecological management. In this investigation, high-resolution (1 m) multibeam echosounder (MBES) depth and backscatter data and derivates, underwater imagery (UI) by video drop-frame, and grab sediment samples, all acquired within 32 km<sup>2</sup> of seafloor in offshore Belgian waters, were integrated to produce a random forest (RF) spatial model, predicting the continuous distribution of the seafloor areal cover/m<sup>2</sup> of the stones’ grain sizes promoting colonisation by sessile epilithic organisms. A semi-automated UI acquisition, processing, and analytical workflow was set up to quantitatively study the colonisation proportion of different grain sizes, identifying the colonisation potential to begin at stones with grain sizes Ø ≥ 2 cm. This parameter (i.e., % areal cover of stones Ø ≥ 2 cm/m<sup>2</sup>) was selected as the response variable for spatial predictive modelling. The model output is presented along with a protocol of error and uncertainty estimation. RF is confirmed as an accurate, versatile, and transferable mapping methodology, applicable to area-wide mapping of SNHS. UI is confirmed as an essential aid to acoustic seafloor classification, providing spatially representative numerical observations needed to carry out quantitative seafloor modelling of ecologically relevant parameters. This contribution sheds innovative insights into the ecologically relevant delineation of subtidal natural reef habitat, exploiting state-of-the-art underwater remote sensing and acoustic seafloor classification approaches.Giacomo Montereale GavazziDanae Athena KapasakaliFrancis KerchofSamuel DeleuSteven DegraerVera Van LanckerMDPI AGarticleunderwater imagerymultibeam echosounderrandom forestsubtidal natural hard substratestone colonisationepilithic faunaScienceQENRemote Sensing, Vol 13, Iss 4608, p 4608 (2021)
institution DOAJ
collection DOAJ
language EN
topic underwater imagery
multibeam echosounder
random forest
subtidal natural hard substrate
stone colonisation
epilithic fauna
Science
Q
spellingShingle underwater imagery
multibeam echosounder
random forest
subtidal natural hard substrate
stone colonisation
epilithic fauna
Science
Q
Giacomo Montereale Gavazzi
Danae Athena Kapasakali
Francis Kerchof
Samuel Deleu
Steven Degraer
Vera Van Lancker
Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning
description Subtidal natural hard substrates (SNHS) promote occupancy by rich benthic communities that provide irreplaceable and fundamental ecosystem functions, representing a global priority target for nature conservation and recognised in most European environmental legislation. However, scientifically validated methodologies for their quantitative spatial demarcation, including information on species occupancy and fine-scale environmental drivers (e.g., the effect of stone size on colonisation) are rare. This is, however, crucial information for sound ecological management. In this investigation, high-resolution (1 m) multibeam echosounder (MBES) depth and backscatter data and derivates, underwater imagery (UI) by video drop-frame, and grab sediment samples, all acquired within 32 km<sup>2</sup> of seafloor in offshore Belgian waters, were integrated to produce a random forest (RF) spatial model, predicting the continuous distribution of the seafloor areal cover/m<sup>2</sup> of the stones’ grain sizes promoting colonisation by sessile epilithic organisms. A semi-automated UI acquisition, processing, and analytical workflow was set up to quantitatively study the colonisation proportion of different grain sizes, identifying the colonisation potential to begin at stones with grain sizes Ø ≥ 2 cm. This parameter (i.e., % areal cover of stones Ø ≥ 2 cm/m<sup>2</sup>) was selected as the response variable for spatial predictive modelling. The model output is presented along with a protocol of error and uncertainty estimation. RF is confirmed as an accurate, versatile, and transferable mapping methodology, applicable to area-wide mapping of SNHS. UI is confirmed as an essential aid to acoustic seafloor classification, providing spatially representative numerical observations needed to carry out quantitative seafloor modelling of ecologically relevant parameters. This contribution sheds innovative insights into the ecologically relevant delineation of subtidal natural reef habitat, exploiting state-of-the-art underwater remote sensing and acoustic seafloor classification approaches.
format article
author Giacomo Montereale Gavazzi
Danae Athena Kapasakali
Francis Kerchof
Samuel Deleu
Steven Degraer
Vera Van Lancker
author_facet Giacomo Montereale Gavazzi
Danae Athena Kapasakali
Francis Kerchof
Samuel Deleu
Steven Degraer
Vera Van Lancker
author_sort Giacomo Montereale Gavazzi
title Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning
title_short Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning
title_full Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning
title_fullStr Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning
title_full_unstemmed Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning
title_sort subtidal natural hard substrate quantitative habitat mapping: interlinking underwater acoustics and optical imagery with machine learning
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/7eeba4cab24d4a92baa376940c1fe3c9
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