Mapping the change of coral reefs using remote sensing and in situ measurements: a case study in Pangkajene and Kepulauan Regency, Spermonde Archipelago, Indonesia

Haya, La Ode Muhammad Yasir; Fujii, Masahiko

doi:10.1007/s10872-017-0422-4

Cited by 25 publications

(8 citation statements)

References 44 publications

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“…Broad scale benthic composition maps over entire reefs with Landsat 8 satellite imagery are promising monitoring resources for researchers and managers [15]. However, the pixel size of moderate spatial resolution satellite imagery is a limiting factor when creating accurate substrate classification models [7].…”

Section: Introductionmentioning

confidence: 99%

Automating Drone Image Processing to Map Coral Reef Substrates Using Google Earth Engine

Bennett

Younes

Joyce

2020

Drones

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While coral reef ecosystems hold immense biological, ecological, and economic value, frequent anthropogenic and environmental disturbances have caused these ecosystems to decline globally. Current coral reef monitoring methods include in situ surveys and analyzing remotely sensed data from satellites. However, in situ methods are often expensive and inconsistent in terms of time and space. High-resolution satellite imagery can also be expensive to acquire and subject to environmental conditions that conceal target features. High-resolution imagery gathered from remotely piloted aircraft systems (RPAS or drones) is an inexpensive alternative; however, processing drone imagery for analysis is time-consuming and complex. This study presents the first semi-automatic workflow for drone image processing with Google Earth Engine (GEE) and free and open source software (FOSS). With this workflow, we processed 230 drone images of Heron Reef, Australia and classified coral, sand, and rock/dead coral substrates with the Random Forest classifier. Our classification achieved an overall accuracy of 86% and mapped live coral cover with 92% accuracy. The presented methods enable efficient processing of drone imagery of any environment and can be useful when processing drone imagery for calibrating and validating satellite imagery.

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Section: Introductionmentioning

confidence: 99%

Automating Drone Image Processing to Map Coral Reef Substrates Using Google Earth Engine

Bennett

Younes

Joyce

2020

Drones

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“…Recently, with the development of remote sensing technology, new progress has been made in the conservation of coral reefs. Yasir Haya and Fujii (2017) used multitemporal Landsat imagery to analyze the ratio of live coral cover. Wei et al (2018) evaluated remote sensing reflectance with a high spatial resolution, which was provided by the Landsat‐8 satellite for optically shallow environments for coral reef studies.…”

Section: Introductionmentioning

confidence: 99%

Tide‐Induced Periodic Sea Surface Temperature Drops in the Coral Reef Area of Nanwan Bay, Southern Taiwan

et al. 2020

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Tidal current-induced cyclonic eddies cause cold-water upwelling and periodic sea surface temperature (SST) drops around the coral reef area in Nanwan Bay, which is located at the southern tip of Taiwan. This study used Himawari-8 satellite data and tide gauge and coastal ocean dynamics application radar (CODAR) data to analyze the characteristics of the SST drops and cyclonic eddy propagation and used an oceanic general circulation model (OGCM) to simulate the tidal current flowing process. According to the CODAR data analysis, the mixed primary semidiurnal tide had an average current velocity of 0.3-0.4 m s −1 throughout the bay, and the average life cycle of a cyclonic eddy is 6.6 hr, with a propagation speed of 0.35 m s −1 . The SST drop during the spring tide period was greater than that during the neap tide period, and the SST dropped in both summer and winter. The average daily SST drop in the summer reached 2°C with a maximum observed value of 4.7°C, and the SST drop rate was 0.3-0.5°C hr −1 . The annual mean chlorophyll-a concentration was 0.25 mg m −3 . This study explored the special properties of the Nanwan Bay coral reef area from the perspective of ocean physics to allow ecologists to facilitate the implementation of long-term conservation and monitoring programs.Plain Language Summary In recent years, the increased global sea temperatures have caused severe coral bleaching; however, Nanwan Bay has suffered a comparatively smaller impact. To understand why, we analyzed satellite and radar data. We found that Nanwan Bay experienced an almost daily sea surface temperature (SST) drop during the summer and that this periodic variation was caused by a cyclonic eddy upwelling cold water to the surface. In the summer, the SST drop was 2°C on average and dropped at a rate of 0.3-0.5°C hr −1 . The observational record indicated that the water cooled as much as 4.7°C in 1 day. These eddies were caused by the unique topography in this area of the bay; they survived an average of 6.6 hr and moved at a rate of 0.35 m s −1 . The formed eddies disappeared in the bay or flowed southward out of the bay. With this study, we hope to help marine ecologists understand the Nanwan Bay environment from a geophysical perspective so that they have sufficient background knowledge when investigating coral biology and coral reef ecology in the future.

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“…In a recent study by Haya and Fujii (2017), analyses of remote sensing data and in situ coral reef surveys revealed a substantial decline in live coral cover within coral reef habitats in the shallow waters (<10 m) of the Spermonde Archipelago. Whereas in 1994 the archipelago was characterized by about 72% of living coral cover, in 2002 this value decreased to 64% and further reduced to 39% in 2014.…”

Section: Anthropogenic Influencementioning

confidence: 99%

Reef Island Evolution and Dynamics: Insights from the Indian and Pacific Oceans and Perspectives for the Spermonde Archipelago

Kench

Mann

2017

Front. Mar. Sci.

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Along southwestern Sulawesi, Indonesia, the Spermonde Archipelago comprises some 120 islands of variable size and degree of anthropogenic modification. Comparable to adjacent areas in Southeast Asia, the Spermonde Archipelago is characterized by the congregation of a naturally high marine biodiversity and, at the same time, a high population density influencing the surrounding environmental conditions. As a consequence, during the last decades, research projects that have been carried out in the Spermonde mainly focused on social, ecological, political and economic interactions. However, geological and geomorphological aspects of the coral reef islands are less well understood and there have been few studies undertaken since the pioneering work of Umbgrove, Kuenen, and Verstappen in the Indonesian archipelago in the early to mid-twentieth century. Here we review the existing studies, with a focus on the Spermonde Archipelago, and reconcile them with more recent works on reef island evolution and dynamics from the Indian and Pacific Oceans. This synthesis shows that reef islands in the Spermonde Archipelago are well suited for geomorphological investigations, and provides perspectives for future reef island research in that area that will have global interest. We identify four research priorities: (1) To identify the timing and chronology of island formation; (2) Improved understanding of carbonate budgets and sediment generation that contribute to island building; (3) Document morphological changes in reef islands at seasonal to decadal timescales, and; (4) Quantify the process regime that drives sediment transport and island change with particular focus on the role of different monsoon seasons.

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Mapping the change of coral reefs using remote sensing and in situ measurements: a case study in Pangkajene and Kepulauan Regency, Spermonde Archipelago, Indonesia

Cited by 25 publications

References 44 publications

Automating Drone Image Processing to Map Coral Reef Substrates Using Google Earth Engine

Automating Drone Image Processing to Map Coral Reef Substrates Using Google Earth Engine

Tide‐Induced Periodic Sea Surface Temperature Drops in the Coral Reef Area of Nanwan Bay, Southern Taiwan

Reef Island Evolution and Dynamics: Insights from the Indian and Pacific Oceans and Perspectives for the Spermonde Archipelago

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