Long-term coastline monitoring on a coral reef island (Moorea, French Polynesia)

Moussa, Rakamaly Madi; Fogg, Lily; Bertucci, Frédéric; Calandra, Maëlle; Collin, Antoine; Aubanel, Annie; Polti, Sandrine; Benet, Agnès; Salvat, Bernard; Galzin, René; Planes, Serge; Lecchini, David

doi:10.1016/j.ocecoaman.2019.104928

Cited by 24 publications

(37 citation statements)

References 19 publications

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“…Vegetation was removed and replaced by private embankments to consolidate infillings (from 3% or 1.2km in 1955 to 46% or 20.3km in 2019). Similar evolutions have been noted on other French Polynesian islands, notably an increase from 12% in 1977 to 57% in 2018 of embankments on the island of Moorea, which has similar geological, geomorphological, and socio-economical characteristics [3]. Through interviews with long-term Bora Bora residents performed in March 2021, it emerged that these embankments were initially linked to a drive to extend the island's land surface outwards and construct houses on the highly sought-after seaside, notably until the 1990s.…”

Section: Changes In Shoreline Position On the Southern Beachessupporting

confidence: 77%

“…method from [14]), as detailed in Table 1. Furthermore, a ground-based survey of the coastal typology was performed in 2019 using a GPS (similar methodology to [3]).…”

Section: Data Acquisitionmentioning

confidence: 99%

“…The coastline was classified into the eight categories that were discernible on aerial images: sandy beaches, mangroves, trees (tall trees on a muddy substrate), grass (or reeds), natural rocky shores, road embankments (and seawalls, necessary for urbanisation purposes), private embankments (to consolidate lands), and quays (cf. Figure 3 and 4; "method similar to [3]). The coastal classification for 2019 was performed first using the ground-based survey of the different coastal typologies to identify the bird-eye aspect of each category (Figure 3) and obtain a baseline from which to work backward in time and classify previous images through photointerpretation.…”

Section: Shoreline Classificationmentioning

confidence: 99%

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Spatiotemporal Trends of Bora Bora’s Shoreline Classification and Movement Using High Resolution Imagery From 1955 to 2019

Gairin¹,

Collin²,

James³

et al. 2021

Preprint

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Coastal urbanisation is a widespread phenomenon throughout the world and is often linked to increased erosion. Small Pacific islands are not spared from this issue, which is of great importance in the context of climate change. The French Polynesian island of Bora Bora was used as a case study to investigate the historical evolution of its coastline classification and position from 1955 to 2019. A time series of very-high-resolution aerial imagery was processed to highlight the changes of the island’s coastline. The overall length of natural shores, including beaches, decreased by 46% from 1955 to 2019 while man-made shores such as seawalls increased by 476%, and as of 2019 represented 61% of the coastline. This evolution alters sedimentary processes: the time series of aerial images highlights increased erosion in the vicinity of seawalls and embankments, leading to the incremental need to construct additional walls. In addition, the gradual removal of natural shoreline types modifies landscapes and may negatively impact marine biodiversity. Through documenting coastal changes on Bora Bora through time, this study highlights the impacts of man-made structures on erosional processes and underscores the need for sustainable coastal management plans in French Polynesia.

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Section: Changes In Shoreline Position On the Southern Beachessupporting

confidence: 77%

“…method from [14]), as detailed in Table 1. Furthermore, a ground-based survey of the coastal typology was performed in 2019 using a GPS (similar methodology to [3]).…”

Section: Data Acquisitionmentioning

confidence: 99%

Section: Shoreline Classificationmentioning

confidence: 99%

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Spatiotemporal Trends of Bora Bora’s Shoreline Classification and Movement Using High Resolution Imagery From 1955 to 2019

Gairin¹,

Collin²,

James³

et al. 2021

Preprint

Self Cite

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“…Extrinsic sources (e.g., local abiotic conditions, food availability) could be at play, given that sub-populations of blacktip reef shark neonates around Moorea occupy such small home ranges 47 and exhibit variable foraging success 33 . Conversely, the small spatial scale and somewhat homogenous coastline of Moorea 48 could mean that blacktip reef shark neonate habitats do not differ greatly in abiotic conditions. Further, there were no correlations between physiological and behavioural traits 8 .…”

Section: Discussionmentioning

confidence: 99%

The power struggle: assessing interacting global change stressors via experimental studies on sharks

Bouyoucos

Watson

Planes

et al. 2020

Sci Rep

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Ocean warming and acidification act concurrently on marine ectotherms with the potential for detrimental, synergistic effects; yet, effects of these stressors remain understudied in large predatory fishes, including sharks. We tested for behavioural and physiological responses of blacktip reef shark (Carcharhinus melanopterus) neonates to climate change relevant changes in temperature (28 and 31 °C) and carbon dioxide partial pressures (pCO2; 650 and 1050 µatm) using a fully factorial design. Behavioural assays (lateralisation, activity level) were conducted upon 7–13 days of acclimation, and physiological assays (hypoxia tolerance, oxygen uptake rates, acid–base and haematological status) were conducted upon 14–17 days of acclimation. Haematocrit was higher in sharks acclimated to 31 °C than to 28 °C. Significant treatment effects were also detected for blood lactate and minimum oxygen uptake rate; although, these observations were not supported by adequate statistical power. Inter-individual variability was considerable for all measured traits, except for haematocrit. Moving forward, studies on similarly ‘hard-to-study’ species may account for large inter-individual variability by increasing replication, testing larger, yet ecologically relevant, differences in temperature and pCO2, and reducing measurement error. Robust experimental studies on elasmobranchs are critical to meaningfully assess the threat of global change stressors in these data-deficient species.

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“…Xiang et al [20] established a new model that can be used to evaluate the sustainable utilization of coastlines so as to obtain the output efficiency of artificial coastlines and the interference degree of human activities on natural coastlines. Moussa et al [21] studied and analyzed the ecological conditions of the coastline of Moorea Island in a long-term study and determined that the factors affecting the changes in the coastline of the island were mainly caused by human beings, and it was necessary to establish a coastline observation station for continuous observation in order to maintain the coastline of the South Pacific island. Liu et al [22] analyzed the problems with coastline utilization in China since the 1990s and put forward opinions and suggestions for coastline protection and utilization.…”

Section: Introductionmentioning

confidence: 99%

Exploring the Spatial–Temporal Analysis of Coastline Changes Using Place Name Information on Hainan Island, China

Xia

Luan

Zhao

et al. 2021

IJGI

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A coastline is the boundary zone between land and sea, an active zone of human social production activities and an area where the ecology is fragile and easy to change. The traditional method to analyze temporal and spatial changes in the coastline is to extract the coastline through remote sensing, LiDAR, and field sampling and analyze the temporal and spatial changes with statistical data. The coastline extracted by these methods has high spatial and temporal resolution, but it requires remote sensing images and data obtained by other sensors, so it is impossible to extract coastlines from before the emergence of remote sensing technology. This paper improves the coastline generation algorithm. Firstly, a triangulated irregular network is used to generate the preliminary rough coastline, and then, each line segment is optimized with Python language according to the influence range of the place names to further approach the real coastline. The accuracy of the coastline extracted by this method can reach 80% within 500 m, which is of great significance in the mapping and analysis of small- and medium-scale coastlines. This paper analyzes the changes in the coastline of Hainan Island before the founding of China (pre-founding) and in modern times and analyzes the impact of coastal development on coastline change. Through the analysis, it is found that, from before the founding of the People’s Republic of China to the present, the natural coastline of Hainan Island has become shorter, the artificial coastline has become longer, and the coastline generally presents a trend of advancing toward the ocean. This method realizes coastline construction under the condition of missing remote sensing images and puts forward a new way to study historical coastline changes.

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Long-term coastline monitoring on a coral reef island (Moorea, French Polynesia)

Cited by 24 publications

References 19 publications

Spatiotemporal Trends of Bora Bora’s Shoreline Classification and Movement Using High Resolution Imagery From 1955 to 2019

Spatiotemporal Trends of Bora Bora’s Shoreline Classification and Movement Using High Resolution Imagery From 1955 to 2019

The power struggle: assessing interacting global change stressors via experimental studies on sharks

Exploring the Spatial–Temporal Analysis of Coastline Changes Using Place Name Information on Hainan Island, China

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