Mapping shallow nearshore benthic features in a Caribbean marine-protected area: assessing the efficacy of using different data types (hydroacoustic versus satellite images) and classification techniques

McIntyre, Karen; McLaren, Kurt; Prospere, Kurt

doi:10.1080/01431161.2017.1395924

Cited by 16 publications

(16 citation statements)

References 67 publications

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“…The transition to deep water is signalled by a sudden drop in WD rel , and a threshold used to exclude these pixels. Discrete zones of WD rel were extracted using a quantile interval method, classified using the same approach as above, and corrected for the presence of coral by thresholding the ratio of the red to green band across all depths [7]. Such hierarchical classification schemes circumvent the effects of water depth changes to benthic reflectance [8].…”

Section: Methodsmentioning

confidence: 99%

The thin(ning) green line? Investigating changes in Kenya's seagrass coverage

2018

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Knowledge of seagrass distribution is limited to a few well-studied sites and poor where resources are scant (e.g. Africa), hence global estimates of seagrass carbon storage are inaccurate. Here, we analysed freely available Sentinel-2 and Landsat imagery to quantify contemporary coverage and change in seagrass between 1986 and 2016 on Kenya's coast. Using field surveys and independent estimates of historical seagrass, we estimate total cover of Kenya's seagrass to be 317.1 + 27.2 km 2 , following losses of 0.85% yr 21 since 1986. Losses increased from 0.29% yr 21 in 2000 to 1.59% yr 21 in 2016, releasing up to 2.17 Tg carbon since 1986. Anecdotal evidence suggests fishing pressure is an important cause of loss and is likely to intensify in the near future. If these results are representative for Africa, global estimates of seagrass extent and loss need reconsidering.

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Section: Methodsmentioning

confidence: 99%

The thin(ning) green line? Investigating changes in Kenya's seagrass coverage

2018

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“…analysis (Baumstark et al, 2016;Collin et al, 2016;McIntyre et al, 2018). However, these studies did undertake quantitative accuracy assessments with data separated into training and testing datasets which we were unable to perform here.…”

Section: Discussionmentioning

confidence: 92%

Rapid Assessment of Seabed Habitats Around Pitcairn Island in Aid of Activity Management During the COVID-19 Global Pandemic

et al. 2021

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The global COVID-19 pandemic of 2020 has forced small island states to make rapid changes to the way they manage their marine estates following changes in global shipping practices and access which are essential for the supply of food items and island’s infrastructure. Following the closure of the border of neighboring French Polynesia, changes had to be made to the Pitcairn Islands’ sole supply vessel route, which resulted in the vessel requiring to set anchor on arrival at the island to conserve fuel. Considering this change and to ensure the continued protection of vulnerable coral habitats the local government has had to make swift decisions to identify anchoring zones that minimize seabed disturbance. Data collected in January 2020, just prior to the pandemic, were assessed using a rapid assessment method and combined with earth observation data to create the first shallow water (<∼20 m) habitat map of this island. The results show the distribution of vulnerable coral communities and other habitats, achieving an accuracy of 68% compared with previously collected datasets making the results the best available evidence for management purposes. Although the seabed data were not originally collected for this analysis, having both video and stills imagery aligned with global positioning meant a rapid assessment method could be easily applied to the data. The assessment technique used has resulted in the first reliable habitat distribution maps to be produced in a management critical timeframe, providing managers with the evidence they required to make informed decisions relating to the protection and conservation of Pitcairn’s pristine, marine habitats during these unprecedented times.

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“…First, to enhance the classification accuracy, it appears evident that a higher satellite image resolution implies a higher accuracy for a same algorithm [224]. Notwithstanding this, we will describe here the different means to enhance the mapping with a given satellite resolution.…”

Section: Additional Inputs To Coral Mappingmentioning

confidence: 99%

Mapping of Coral Reefs with Multispectral Satellites: A Review of Recent Papers

et al. 2021

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Coral reefs are an essential source of marine biodiversity, but they are declining at an alarming rate under the combined effects of global change and human pressure. A precise mapping of coral reef habitat with high spatial and time resolutions has become a necessary step for monitoring their health and evolution. This mapping can be achieved remotely thanks to satellite imagery coupled with machine-learning algorithms. In this paper, we review the different satellites used in recent literature, as well as the most common and efficient machine-learning methods. To account for the recent explosion of published research on coral reel mapping, we especially focus on the papers published between 2018 and 2020. Our review study indicates that object-based methods provide more accurate results than pixel-based ones, and that the most accurate methods are Support Vector Machine and Random Forest. We emphasize that the satellites with the highest spatial resolution provide the best images for benthic habitat mapping. We also highlight that preprocessing steps (water column correction, sunglint removal, etc.) and additional inputs (bathymetry data, aerial photographs, etc.) can significantly improve the mapping accuracy.

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Mapping shallow nearshore benthic features in a Caribbean marine-protected area: assessing the efficacy of using different data types (hydroacoustic versus satellite images) and classification techniques

Cited by 16 publications

References 67 publications

The thin(ning) green line? Investigating changes in Kenya's seagrass coverage

The thin(ning) green line? Investigating changes in Kenya's seagrass coverage

Rapid Assessment of Seabed Habitats Around Pitcairn Island in Aid of Activity Management During the COVID-19 Global Pandemic

Mapping of Coral Reefs with Multispectral Satellites: A Review of Recent Papers

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