scholarly journals Confidence Levels, Sensitivity, and the Role of Bathymetry in Coral Reef Remote Sensing

2020 ◽  
Vol 12 (3) ◽  
pp. 496 ◽  
Author(s):  
James A. Goodman ◽  
Mui Lay ◽  
Luis Ramirez ◽  
Susan L. Ustin ◽  
Paul J. Haverkamp
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Coral Reefs ◽  
Water Depth ◽  
Data Availability ◽  
Sensor Technology ◽  
Internal Quality ◽  
Benthic Habitat ◽  
Model Output ◽  
Confidence Levels

Remote sensing is playing an increasingly important role in the monitoring and management of coastal regions, coral reefs, inland lakes, waterways, and other shallow aquatic environments. Ongoing advances in algorithm development, sensor technology, computing capabilities, and data availability are continuing to improve our ability to accurately derive information on water properties, water depth, benthic habitat composition, and ecosystem health. However, given the physical complexity and inherent variability of the aquatic environment, most of the remote sensing models used to address these challenges require localized input parameters to be effective and are thereby limited in geographic scope. Additionally, since the parameters in these models are interconnected, particularly with respect to bathymetry, errors in deriving one parameter can significantly impact the accuracy of other derived parameters and products. This study utilizes hyperspectral data acquired in Hawaii in 2000–2001 and 2017–2018 using NASA’s Classic Airborne Visible/Infrared Imaging Spectrometer to evaluate performance and sensitivity of a well-established semi-analytical inversion model used in the assessment of coral reefs. Analysis is performed at several modeled spatial resolutions to emulate characteristics of different feasible moderate resolution hyperspectral satellites, and data processing is approached with the objective of developing a generalized, scalable, automated workflow. Accuracy of derived water depth is evaluated using bathymetric lidar data, which serves to both validate model performance and underscore the importance of image quality on achieving optimal model output. Data are then used to perform a sensitivity analysis and develop confidence levels for model validity and accuracy. Analysis indicates that derived benthic reflectance is most sensitive to errors in bathymetry at shallower depths, yet remains significant at all depths. The confidence levels provide a first-order method for internal quality assessment to determine the physical extent of where and to what degree model output is considered valid. Consistent results were found across different study sites and different spatial resolutions, confirming the suitability of the model for deriving water depth in complex coral reef environments, and expanding our ability to achieve automated widespread mapping and monitoring of global coral reefs.

scholarly journals Reconstructing High-Precision Coral Reef Geomorphology from Active Remote Sensing Datasets: A Robust Spatial Variability Modified Ordinary Kriging Method

2022 ◽  
Vol 14 (2) ◽  
pp. 253
Author(s):  
Qi Wang ◽  
Han Xiao ◽  
Wenzhou Wu ◽  
Fenzhen Su ◽  
Xiuling Zuo ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Coral Reefs ◽  
Spatial Variability ◽  
High Precision ◽  
Ordinary Kriging ◽  
Surface Model ◽  
Smoothing Effect ◽  
Geomorphological Parameters ◽  
Reef Geomorphology

Active remote sensing technology represented by multi-beam and lidar provides an important approach for the effective acquisition of underwater coral reef geomorphological information. A spatially continuous surface model of coral reef geomorphology reconstructed from active remote sensing datasets can provide important geomorphological parameters for the research of coral reef geomorphological and ecological changes. However, the surface modeling methods commonly used in previous studies, such as ordinary kriging (OK) and natural neighborhood (NN), often represent a “smoothing effect”, which causes the strong spatial variability of coral reefs to be imprecisely reflected by the reconstructed surfaces, thus affecting the accurate calculation of subsequent geomorphological parameters. In this study, a spatial variability modified OK (OK-SVM) method is proposed to reduce the impact of the “smoothing effect” on the high-precision reconstruction of the complex geomorphology of coral reefs. The OK-SVM adopts a collaborative strategy of global parameter transformation, local residual correction, and extremum correction to modify the spatial variability of the reconstructed model, while maintaining high local accuracy. The experimental results show that the OK-SVM has strong robustness to spatial variability modification. This method was applied to the geomorphological reconstruction of the northern area of a coral atoll in the Nansha Islands, South China Sea, and the performance was compared with that of OK and NN. The results show that OK-SVM has higher numerical accuracy and attribute accuracy in detailed morphological fidelity, and is more adaptable in the geomorphological reconstruction of coral reefs with strong spatial variability. This method is relatively reliable for achieving high-precision reconstruction of complex geomorphology of coral reefs from active remote sensing datasets, and has potential to be extended to other geomorphological reconstruction applications.

scholarly journals Representative benthic habitat mapping on Lovina coral reefs in Northern Bali, Indonesia

2021 ◽  
Vol 22 (11) ◽  
Author(s):  
Anggita Kartikasari ◽  
TODHI PRISTIANTO ◽  
RIZKI HANINTYO ◽  
EGHBERT ELVAN AMPOU ◽  
TEJA ARIEF WIBAWA ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Habitat Mapping ◽  
Benthic Habitat ◽  
Coral Rubble ◽  
Spatial Coverage ◽  
Coral Reef Ecosystems ◽  
Optical Imagery ◽  
Sentinel 2

Abstract. Kartikasari A, Pristianto T, Hanintyo R, Ampou EE, Wibawa TA, Borneo BB. 2021. Representative benthic habitat mapping on Lovina coral reefs in Northern Bali, Indonesia. Biodiversitas 22: 4766-4774. Satellite optical imagery datasets integrated with in situ measurements are widely used to derive the spatial distribution of various benthic habitats in coral reef ecosystems. In this study, an approach to estimate spatial coverage of those habitats based on observation derived from Sentinel-2 optical imagery and a field survey, is presented. This study focused on the Lovina coral reef ecosystem of Northern Bali, Indonesia to support deployment of artificial reefs within the Indonesian Coral Reef Garden (ICRG) programme. Three specific locations were explored: Temukus, Tukad Mungga, and Baktiseraga waters. Spatial benthic habitat coverages of these three waters was estimated based on supervised classification techniques using 10m bands of Sentinel-2 imagery and the medium scale approach (MSA) transect method of in situ measurement.The study indicates that total coverage of benthic habitat is 61.34 ha, 25.17 ha, and 27.88 ha for Temukus, Tukad Mungga, and Baktiseraga waters, respectively. The dominant benthic habitat of those three waters consists of sand, seagrass, coral, rubble, reef slope and intertidal zone. The coral reef coverage is 29.48 ha (48%) for Temukus covered by genus Acropora, Isopora, Porites, Montipora, Pocillopora. The coverage for Tukad Mungga is 8.69 ha (35%) covered by genus Acropora, Montipora, Favia, Psammocora, Porites, and the coverage for Baktiseraga is 11.37 ha (41%) covered by genus Montipora sp, Goniastrea, Pavona, Platygyra, Pocillopora, Porites, Acropora, Leptoseris, Acropora, Pocillopora, Fungia. The results are expected to be suitable as supporting data in restoring coral reef ecosystems in the northern part of Bali, especially in Buleleng District.

The scientific issues surrounding remote detection of submerged coral ecosystems

1998 ◽  
Vol 22 (2) ◽  
pp. 190-221 ◽  
Author(s):  
Heather Holden ◽  
Ellsworth LeDrew
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Coral Reefs ◽  
Large Scale ◽  
Aerial Photographs ◽  
Coastal Zones ◽  
Global Status ◽  
Coral Reef Ecosystems ◽  
Remote Estimation

According to the 1993 colloquium on the ‘Global status of coral reefs', our understanding of the global role of coral reefs is inadequate. To increase our understanding, an accurate large-scale mapping and monitoring programme is necessary. Historically, coastal zones have been mapped using traditional surveying tools such as topographic maps, nautical charts, existing aerial photographs and direct observations. Although less expensive than digital imagery, exclusive use of these traditional tools may not be practical for monitoring large or remote coral reef ecosystems accurately. Researchers are attempting to develop an adequate coral reef mapping system based on digital remote sensing, but are impeded by issues such as effects of the intervening water column and spectral distinction of bottom types. The two variables discussed, which will contribute to our understanding of the global role of coral reefs, are: 1) remote sensing of submerged coral reefs in general; and 2) remote sensing of coral bleaching in particular. A summary of radiative transfer theory is presented and case studies of attempts at mapping remotely the geographic extent and health of submerged ecosystems, as well as a discussion of the remote estimation of water depth and quality. Problems in the translation and delivery of information to the end user are presented, and possible solutions suggested.

scholarly journals Coral Reef Drag Coefficients – Water Depth Dependence

2017 ◽  
Vol 47 (5) ◽  
pp. 1061-1075 ◽  
Author(s):  
S. J. Lentz ◽  
K. A. Davis ◽  
J. H. Churchill ◽  
T. M. DeCarlo
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Drag Coefficient ◽  
Water Depth ◽  
Open Channel ◽  
Momentum Balance ◽  
Laboratory Studies ◽  
Drag Coefficients ◽  
Significant Term ◽  
The Cross

AbstractA major challenge in modeling the circulation over coral reefs is uncertainty in the drag coefficient because existing estimates span two orders of magnitude. Current and pressure measurements from five coral reefs are used to estimate drag coefficients based on depth-average flow, assuming a balance between the cross-reef pressure gradient and the bottom stress. At two sites wind stress is a significant term in the cross-reef momentum balance and is included in estimating the drag coefficient. For the five coral reef sites and a previous laboratory study, estimated drag coefficients increase as the water depth decreases consistent with open channel flow theory. For example, for a typical coral reef hydrodynamic roughness of 5 cm, observational estimates, and the theory indicate that the drag coefficient decreases from 0.4 in 20 cm of water to 0.005 in 10 m of water. Synthesis of results from the new field observations with estimates from previous field and laboratory studies indicate that coral reef drag coefficients range from 0.2 to 0.005 and hydrodynamic roughnesses generally range from 2 to 8 cm. While coral reef drag coefficients depend on factors such as physical roughness and surface waves, a substantial fraction of the scatter in estimates of coral reef drag coefficients is due to variations in water depth.

scholarly journals Coral reef monitoring in Panjang Island, Central Bangka

2021 ◽  
Vol 926 (1) ◽  
pp. 012099
Author(s):  
W Adi ◽  
I Akhrianti ◽  
M Hudatwi
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Coral Reefs ◽  
Satellite Imagery ◽  
Good Condition ◽  
Aerial Photographs ◽  
Visual Interpretation ◽  
Composite Band ◽  
Sentinel 2A ◽  
Color Composite

Abstract Bangka Island is the largest tin producer in Indonesia and since the granting of tin mining freedom in 2000, unconventional tin mining (TI) is increasingly prevalent. The existence of mining activities will directly or indirectly damage the environment both on land and at sea. Especially the high biodiversity of coral reef ecosystem. The purpose of this research was to analyze a map of the distribution of coral reef based on Sentinel 2A satellite imagery data. Analyze the extent of the coral reefs in shallow waters of Putri Island, and analyze of the condition coral reefs (percentage cover, mortality index and genus diversity) with using collaboration betwen the coral diving data and remote sensing data. Studies of changes in coral reef ecosystems have been ongoing since several decades ago. The combination of satellite imagery and aerial photographs is capable of making long-term and continuous observations on mapping and change detection. Remote sensing technology has several advantages overconventional sampling to monitor a large area in time almost simultaneously and continuously including the difficult to explore areas. This research was conducted with visual interpretation by using standard true color composite band (483) and false color composite band (843) of Sentinel 2A and also using lyzenga transformation. Estimation of coral reefs area based on result is 475,96 ha (2016) and decreased to 475 ha (2021). The condition of coral reefs at the research location is a good condition.

scholarly journals ANALISIS HABITAT DAN PERUBAHAN LUASAN TERUMBU KARANG DI PULAU MENJANGAN BESAR, KEPULAUAN KARIMUNJAWA MENGGUNAKAN CITRA SATELIT

2016 ◽  
Vol 5 (4) ◽  
pp. 302-310
Author(s):  
Rio Januardi ◽  
Agus Hartoko ◽  
Pujiono Wahyu Purnomo
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Coral Reefs ◽  
Good Condition ◽  
Landsat 8 ◽  
Geometric Center ◽  
Sensing Technology ◽  
Coral Reef Area ◽  
Short Time ◽  
Line Intercept

ABSTRAK Perairan Indonesia menyimpan keanekaragaman hayati laut karang tertinggi, diperkirakan luas ekosistem terumbu karang Indonesia mencapai 50.000 km2 yaitu 25 persen dari luas terumbu karang dunia. Penggunaan teknologi penginderaan jauh merupakan salah satu alternatif yang tepat untuk mendeteksi terumbu karang bagi negara yang mempunyai wilayah yang sangat luas dan memerlukan waktu yang relatif singkat serta biaya murah. Penelitian ini bertujuan untuk mengetahui jenis, kondisi, perubahan luasan dan tingkat akurasi monitoring terumbu karang di Pulau Menjangan Besar menggunakan citra satelit Landsat 8. Penelitian dilaksanakan pada November 2015-Januari 2016 di Pulau Menjangan Besar dan di Laboratorium Marine Geometric Center, Jurusan Perikanan UNDIP. Metode penelitian yang digunakan yaitu metode eksploratif untuk mengetahui jenis dan kondisi terumbu karang menggunakan metode Line Intersept Transect dan metode koreksi kolom air atau Lyzenga. Hasil penelitian  menemukan kondisi terumbu karang di Pulau Menjangan Besar masih dalam kondisi baik dengan persentase penutupan karang sebesar 51,6 persen. Jenis terumbu karang yang terdapat di Pulau Menjangan Besar yaitu Acropora sp, Stylopora sp, Porites sp, Favia sp, Heliopora sp, Euphylia sp, Pocilopora sp, Goniopora sp dan Favites sp dengan nilai keaneragaman sebesar 1.28 tergolong sedang/moderat dan nilai dominasi sebesar 0.58. Terumbu karang mengalami penurunan luasan sebesar 7,92 Ha dari tahun 2013-2015. Tingkat akurasi penggunaan citra satelit Landsat 8 yaitu 81,25 persen. Kata kunci :Persentase penutupan karang; Luasan habitat; Menjangan Besar; Penginderaan jauh ABSTRACTThe ocean of Indonesia has the highest biodiversity of Coral Reef, the extent of Indonesian’s coral reefs widely predicted 50.000 km2 which is about 25% of the world’s. The use of remote sensing technology is one the alternatives that is appropriate for the detection of coral reefs for a country that has a very wide area and requires a relatively short time and reasonable cost. This study aimed to determine the type; condition; changes in the area; and the level of monitoring coral reefs accuracy in Menjangan Besar Island used Landsat 8 satellite. The study was conducted on November 2015 until January 2016 in Menjangan Besar Island and the Marine Geometric Center, Fisheries Department at Diponegoro University. This research uses an explorative method to determine the type and condition of coral reefs using line intercept transect method and correction on water column method or Lyzenga. The result of this research is the condition of coral reefs in Menjangan Besar in the good condition with the cover percentage of coral at 51.6%. The species of Coral reefs in Menjangan Besar are identified as Acropora sp, Stylopora sp, Porites sp, Favia sp, Heliopora sp, Euphylia sp, Pocilopora sp, Goniopora sp and Favites sp with the value of diversity about 1.28 classified as moderate and the value of dominance of 0.58. The coral reef area decreased by 7.92 ha of the year 2013 to 2015. The accuracy level used Landsat 8 imagery satellite is 81.25%. This level of accuracy using Landsat 8 satellite imagery is 81.25%. Keywords :Percentages of coral reef cover; Extents habitat; Menjangan Besar; Remote sensing.

FORAMINIFERA BENTONIK SEBAGAI BIOINDIKATOR KUALITAS PERAIRAN TERUMBU KARANG DI PULAU TEGAL, TELUK LAMPUNG, LAMPUNG

2019 ◽  
Vol 17 (2) ◽  
Author(s):  
Sevina Rahmi ◽  
Suwarno Hadisusanto ◽  
Nazar Nurdin ◽  
Mira Yosi
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Water Depth ◽  
Coral Reef Ecosystem ◽  
Reef Community ◽  
Tourist Destinations ◽  
Low Diversity ◽  
Almost All ◽  
Reef Ecosystem

Foraminifera telah banyak digunakan sebagai indikator kualitas perairan sekitar terumbu karang di Indonesia berdasarkan perbandingan kelompok foraminifera bentonik tertentu. Studi tersebut diterapkan di sekitar Pulau Tegal, Teluk Lampung yang merupakan salah satu destinasi wisata yang secara tidak langsung memberikan pengaruh terhadap ekosistem terumbu karang. Penelitian ini bertujuan untuk mengetahui struktur komunitas foraminifera bentonik kaitannya dengan kondisi perairan terumbu karang Pulau Tegal, Teluk Lampung. Penelitian ini dilakukan pada 16 stasiun penelitian di Pulau Tegal yang mewakili semua sisi pulau dengan variasi kedalaman dari 0 meter hingga 28 meter. Hasil dari penelitian ini ditemukan 6.918 spesimen foraminifera bentonik dengan keanekaragaman yang tergolong rendah. Genera Amphistegina dan Elphidium ditemukan sangat melimpah pada hampir seluruh stasiun. Nilai Indeks FORAM (FI) diatas 4 ditemukan pada 11 stasiun penelitian yang mengindikasikan bahwa sebagian besar perairan Pulau Tegal berada dalam kondisi yang sangat baik dan kondusif untuk pertumbuhan serta pemulihan terumbu karang. Hasil ini sejalan dengan melimpahnya kehadiran kelompok foraminifera yang berasosiasi dengan terumbu karang pada perairan Pulau Tegal.Kata Kunci: Bioindikator, Pulau Tegal, Indeks FORAM, Terumbu Karang, Komunitas.Foraminifera has been widely used as an indicator of the quality of the waters around coral reefs in Indonesia based on the comparison of certain groups of benthonic foraminifera. The study was implemented around Tegal Island, Lampung Bay, which is one of the tourist destinations that influence the coral reef ecosystem. This study aims to determine the structure of bentonic foraminifera communities related to the condition of the coral reef waters of Tegal Island, Lampung Bay. This research was conducted at 16 research stations in Tegal Island representing all sides of the island with variations in depth from 0 m to 28 m water depth. The results of this study found 6.918 specimens of bentonic foraminifera with relatively low diversity. The genera Amphistegina and Elphidium were found to be very abundant in almost all stations. The FORAM Index (FI) above 4 was found in 11 research stations which indicated that most of the waters of Tegal Island were in very good conditions and conducive to the growth and recovery of coral reefs. This result is in line with the abundance of the presence of foraminifera groups associated with coral reefs in the waters of Tegal Island. Keywords: Bioindicator, Tegal Island, FORAM Index, Coral Reef, Community

scholarly journals CORAL REEF HABITAT CHANGING ASSESSMENT OF DERAWAN ISLANDS, EAST KALIMANTAN, USING REMOTE SENSING DATA

2010 ◽  
Vol 2 (-) ◽  
Author(s):  
MARLINA NURLIDIASARI ◽  
SYARIF BUDIMAN
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Coral Reefs ◽  
Change Detection ◽  
Remote Sensing Data ◽  
Landsat Tm ◽  
East Kalimantan ◽  
Marine Diversity ◽  
Multi Temporal ◽  
Remote Sensing Techniques

Coral reefs in Dcrawan Islands are astonishingly rich in the marine diversity. However, these reefs are threatened by humans. Destructive fishing methods, such as trawl, blasting and cyanide fishing practise, are found to be the main cause of this degradation. The coral reefs habitat reduction is also caused by tourism activities due to trampling over the reef and charging organic and anorganic wastes. The capabilities of satellite remote sensing techniques combined with field data collection have been assessed for the coral reef mapping and the change detection of Derawan Island. Multi-temporal Landsat TM and ETM images (1991 and 2002) have been used. Comparison of the classified images of 1991 and 2002 shows spatial changes of the habitat. The changes were in accordance with the known changes in the reef conditions. The analysis shows the decrease of the coral reef and patchy seagrass percentage, while the increase of the algae composite and patchy reef percentage. Keywords : Coral Reef, Change Detection, Landsat-TM, Derawan

Which Spectral Bands of WorldView-2 Are Useful in Remote Sensing of Water Depth? A Case Study in Coral Reefs

2014 ◽  
Vol 37 (3) ◽  
pp. 283-292 ◽  
Author(s):  
Ariyo Kanno ◽  
Yoji Tanaka ◽  
Ryuichiro Shinohara ◽  
Akira Kurosawa ◽  
Masahiko Sekine
Keyword(s):  
Remote Sensing ◽  
Coral Reefs ◽  
Water Depth ◽  
Spectral Bands

scholarly journals Detection of Coral Reef Bleaching Based on Sentinel-2 Multi-Temporal Imagery: Simulation and Case Study

2021 ◽  
Vol 8 ◽  
Author(s):  
Jingping Xu ◽  
Jianhua Zhao ◽  
Fei Wang ◽  
Yanlong Chen ◽  
Zhongping Lee
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Spatial Resolution ◽  
Water Depth ◽  
Coral Bleaching ◽  
Signal Attenuation ◽  
Change Analysis ◽  
Multi Temporal ◽  
Sentinel 2

Sentinel-2 mission has been shown to have promising applications in coral reef remote sensing because of its superior properties. It has a 5-day revisit time, spatial resolution of 10 m, free data, etc. In this study, Sentinel-2 imagery was investigated for bleaching detection through simulations and a case study over the Lizard Island, Australia. The spectral and image simulations based on the semianalytical (SA) model and the sensor spectral response function, respectively, confirmed that coral bleaching cannot be detected only using one image, and the change analysis was proposed for detection because there will be a featured change signal for bleached corals. Band 2 of Sentinel-2 is superior to its other bands for the overall consideration of signal attenuation and spatial resolution. However, the detection capability of Sentinel-2 is still limited by the water depth. With rapid signal attenuation due to the water absorption effect, the applicable water depth for bleaching detection was recommended to be less than 10 m. The change analysis was conducted using two methods: one radiometric normalization with pseudo invariant features (PIFs) and the other with multi-temporal depth invariant indices (DII). The former performed better than the latter in terms of classification. The bleached corals maps obtained using the PIFs and DII approaches had an overall accuracy of 88.9 and 57.1%, respectively. Compared with the change analysis based on two dated images, the use of a third image that recorded the spectral signals of recovered corals or corals overgrown by algae after bleaching significantly improved the detection accuracy. All the preliminary results of this article will aid in the future studies on coral bleaching detection based on remote sensing.

Sign in / Sign up

Export Citation Format

Share Document