Artificial reef effectiveness changes among types as revealed by underwater hyperspectral imagery

Riera, Elisabeth; Hubas, Cédric; Ungermann, Mischa; Rigot, Guy; Pey, Alexis; Francour, Patrice; Rossi, Francesca

doi:10.1111/rec.13978

Cited by 3 publications

(2 citation statements)

References 33 publications

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“…Lafac Bay is an excellent candidate to evaluate the recovery potential of western Pacific reefs following natural disturbance events. Underwater hyperspectral imaging and automated benthic classification remain novel approaches to reef monitoring [ 74 , 87 , 117 , 122 – 124 ], which can provide accurate estimates of benthic community composition. These advancing technologies will benefit monitoring programs, especially those that rely on frequent, rapid, and accurate assessments of dynamic reef communities like those at Lafac Bay.…”

Section: Discussionmentioning

confidence: 99%

Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam

Mills,

Ungermann,

Rigot

et al. 2024

PLoS ONE

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The island of Guam in the west Pacific has seen a significant decrease in coral cover since 2013. Lafac Bay, a marine protected area in northeast Guam, served as a reference site for benthic communities typical of forereefs on the windward side of the island. The staghorn coral Acropora abrotanoides is a dominant and characteristic ecosystem engineer of forereef communities on exposed shorelines. Photoquadrat surveys were conducted in 2015, 2017, and 2019, and a diver-operated hyperspectral imager (i.e., DiveRay) was used to survey the same transects in 2019. Machine learning algorithms were used to develop an automated pipeline to assess the benthic cover of 10 biotic and abiotic categories in 2019 based on hyperspectral imagery. The cover of scleractinian corals did not differ between 2015 and 2017 despite being subjected to a series of environmental disturbances in these years. Surveys in 2019 documented the almost complete decline of the habitat-defining staghorn coral Acropora abrotanoides (a practically complete disappearance from about 10% cover), a significant decrease (~75%) in the cover of other scleractinian corals, and a significant increase (~55%) in the combined cover of bare substrate, turf algae, and cyanobacteria. The drastic change in community composition suggests that the reef at Lafac Bay is transitioning to a turf algae-dominated community. However, the capacity of this reef to recover from previous disturbances suggests that this transition could be reversed, making Lafac Bay an excellent candidate for long-term monitoring. Community analyses showed no significant difference between automatically classified benthic cover estimates derived from the hyperspectral scans in 2019 and those derived from photoquadrats. These findings suggest that underwater hyperspectral imagers can be efficient and effective tools for fast, frequent, and accurate monitoring of dynamic reef communities.

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Section: Discussionmentioning

confidence: 99%

Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam

Mills,

Ungermann,

Rigot

et al. 2024

PLoS ONE

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“…It increases the local biodiversity and stimulates the recovery of ecosystems [27,83,84]. AM technology improves the efficiency of the recultivation process in comparison with traditional artificial reefs (concrete molds with simple geometric shapes) [85].…”

Section: Artificial Reefsmentioning

confidence: 99%

Additive Manufacturing in Underwater Applications

Korniejenko,

Gądek,

Dynowski

et al. 2024

Applied Sciences

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Additive manufacturing (AM), commonly named 3D printing, is a promising technology for many applications. It is the most viable option for widespread use in automated construction processes, especially for harsh environments such as underwater. Some contemporary applications of this technology have been tested in underwater environments, but there are still a number of problems to be solved. This study focuses on the current development of 3D printing technology for underwater applications, including the required improvements in the technology itself, as well as new materials. Information about underwater applications involving part fabrication via AM is also provided. The article is based on a literature review that is supplemented by case studies of practical applications. The main findings show that the usage of additive manufacturing in underwater applications can bring a number of advantages—for instance, increasing work safety, limiting the environmental burden, and high efficiency. Currently, only a few prototype applications for this technology have been developed. However, underwater additive manufacturing is a promising tool to develop new, effective applications on a larger scale. The technology itself, as well as the materials used, still require development and optimization.

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Assessment of the utility of underwater hyperspectral imaging for surveying and monitoring coral reef ecosystems

Mills,

Ungermann,

Rigot

et al. 2023

Sci Rep

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Technological innovations that improve the speed, scale, reproducibility, and accuracy of monitoring surveys will allow for a better understanding of the global decline in tropical reef health. The DiveRay, a diver-operated hyperspectral imager, and a complementary machine learning pipeline to automate the analysis of hyperspectral imagery were developed for this purpose. To evaluate the use of a hyperspectral imager underwater, the automated classification of benthic taxa in reef communities was tested. Eight reefs in Guam were surveyed and two approaches for benthic classification were employed: high taxonomic resolution categories and broad benthic categories. The results from the DiveRay surveys were validated against data from concurrently conducted photoquadrat surveys to determine their accuracy and utility as a proxy for reef surveys. The high taxonomic resolution classifications did not reliably predict benthic communities when compared to those obtained by standard photoquadrat analysis. At the level of broad benthic categories, however, the hyperspectral results were comparable to those of the photoquadrat analysis. This was particularly true when estimating scleractinian coral cover, which was accurately predicted for six out of the eight sites. The annotation libraries generated for this study were insufficient to train the model to fully account for the high biodiversity on Guam’s reefs. As such, prediction accuracy is expected to improve with additional surveying and image annotation. This study is the first to directly compare the results from underwater hyperspectral scanning with those from traditional photoquadrat survey techniques across multiple sites with two levels of identification resolution and different degrees of certainty. Our findings show that dependent on a well-annotated library, underwater hyperspectral imaging can be used to quickly, repeatedly, and accurately monitor and map dynamic benthic communities on tropical reefs using broad benthic categories.

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Artificial reef effectiveness changes among types as revealed by underwater hyperspectral imagery

Cited by 3 publications

References 33 publications

Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam

Coral reefs in transition: Temporal photoquadrat analyses and validation of underwater hyperspectral imaging for resource-efficient monitoring in Guam

Additive Manufacturing in Underwater Applications

Assessment of the utility of underwater hyperspectral imaging for surveying and monitoring coral reef ecosystems

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