French Territories in the Western Indian Ocean

Bigot, Lionel; Chabanet, Pascale; Cuet, Pascale; Cauvin, Bruce; Durville, Patrick; Mulochau, Thierry; Naim, Odile; Nicet, Jb; Tessier, Emmanuel; Thomassin, B. A.; Wickel, Julien

doi:10.1016/b978-0-08-100853-9.00011-7

Cited by 6 publications

(4 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Across all of these events the reefs have apparently achieved considerable recovery and maintained the same dominance by Acropora . This suggests a high degree of community resilience, likely partly a result of high levels of connectivity ( Crochelet et al, 2016 ) due to the complex eddies that maintain high self-seeding of reefs within the northern Mozambique channel ( Obura et al, 2018 ; Bigot et al, 2018 ).…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Coral responses to a repeat bleaching event in Mayotte in 2010

Obura

Bigot

Benzoni

2018

PeerJ

View full text Add to dashboard Cite

BackgroundHigh sea surface temperatures resulted in widespread coral bleaching and mortality in Mayotte Island (northern Mozambique channel, Indian Ocean: 12.1°S, 45.1°E) in April–June 2010. MethodsTwenty three representative coral genera were sampled quantitatively for size class distributions during the peak of the bleaching event to measure its impact. ResultsFifty two percent of coral area was impacted, comprising 19.3% pale, 10.7% bleached, 4.8% partially dead and 17.5% recently dead. Acropora, the dominant genus, was the second most susceptible to bleaching (22%, pale and bleached) and mortality (32%, partially dead and dead), only exceeded by Pocillopora (32% and 47%, respectively). The majority of genera showed intermediate responses, and the least response was shown by Acanthastrea and Leptastrea (6% pale and bleached). A linear increase in bleaching susceptibility was found from small colonies (<2.5 cm, 83% unaffected) to large ones (>80 cm, 33% unaffected), across all genera surveyed. Maximum mortality in 2010 was estimated at 32% of coral area or biomass, compared to half that (16%), by colony abundance.DiscussionMayotte reefs have displayed a high level of resilience to bleaching events in 1983, 1998 and the 2010 event reported here, and experienced a further bleaching event in 2016. However, prospects for continued resilience are uncertain as multiple threats are increasing: the rate of warming experienced (0.1 °C per decade) is some two to three times less than projected warming in coming decades, the interval between severe bleaching events has declined from 16 to 6 years, and evidence of chronic mortality from local human impacts is increasing. The study produced four recommendations for reducing bias when monitoring and assessing coral bleaching: coral colony size should be measured, unaffected colonies should be included in counts, quadrats or belt transects should be used and weighting coefficients in the calculation of indices should be used with caution.

show abstract

Section: Discussionmentioning

confidence: 99%

“…2 ). The island is densely populated, with high pressure on the lagoon from fishing, and sedimentation from runoff and land-use change ( Thomassin, 2001 ; Bigot et al, 2018 ).…”

Section: Methodsmentioning

confidence: 99%

Coral responses to a repeat bleaching event in Mayotte in 2010

Obura

Bigot

Benzoni

2018

PeerJ

View full text Add to dashboard Cite

show abstract

“…Across all of these events the reefs have apparently achieved considerable recovery and maintained the same dominance by Acropora. This suggests a high degree of community resilience, likely partly a result of high levels of connectivity (Crochelet et al 2015) due to the complex eddies that maintain high self-seeding of reefs within the northern Mozambique channel (Obura et al, 2018;Bigot et al 2018).…”

Section: Recurring Bleaching In Mayottementioning

confidence: 99%

Peer Review #1 of "Coral responses to a repeat bleaching event in Mayotte in 2010 (v0.1)"

Eakin¹

2018

View full text Add to dashboard Cite

Background: High sea surface temperatures resulted in widespread coral bleaching and mortality in Mayotte Island (northern Mozambique channel, Indian Ocean: 12.1 o S, 45.1 o E) in April-June 2010. Methods: Twenty three representative coral genera were sampled quantitatively for size class distributions during the peak of the bleaching event, to measure its impact. Results. Fifty two percent of coral area was impacted, comprising 19.3% pale, 10.7% bleached, 4.8% partially dead and 17.5% recently dead. Acropora, the dominant genus, was the second most susceptible to bleaching (22%, pale and bleached) and mortality (32%, partially dead and dead), only exceeded by Pocillopora (32% and 47%, respectively). The majority of genera showed intermediate responses, and the least response was shown by Acanthastrea and Leptastrea (6% pale and bleached). A linear increase in bleaching susceptibility was found from small colonies (< 2.5 cm, 83% unaffected) to large ones (> 80 cm, 33% unaffected), across all genera surveyed. Maximum mortality in 2010 was estimated at 32% of coral area or biomass, compared to half that (16%), by colony abundance. Discussion. Mayotte reefs have displayed a high level of resilience to bleaching events in 1983, 1998 and the 2010 event reported here, and experienced a further bleaching event in 2016. However, prospects for continued resilience are uncertain as multiple threats are increasing: the rate of warming experienced (0.1 o C per decade) is some 2-3 times less than projected warming in coming decades, the interval between severe bleaching events has declined from 16 to 6 years, and evidence of chronic mortality from local human impacts is increasing. The study produced four recommendations for reducing bias when monitoring and assessing coral bleaching: coral colony size should be measured, unaffected colonies should be included in counts, quadrats or belt transects should be used and weighting coefficients in the calculation of indices should be used with caution.

show abstract

“…These territories are surrounded by deep waters and are remarkably isolated, making them ideal to study diffusion of eDNA in natural coral reef conditions with little influence from nearby systems. Previous studies have demonstrated the exceptionally pristine status of their coral reefs, with abundant large fish and predator occurrences (Bigot et al., 2019; Chabanet & Durville, 2007), which, together with the prevalence of currents and eddies, indicates their potential as a biodiversity hotspot (Bigot et al., 2019; Quod et al., 2007). Furthermore, these isolated islands are inhabited only by small military detachments, making them appropriate locations to investigate biodiversity with little direct anthropogenic influence (Conand et al., 2013).…”

Section: Introductionmentioning

confidence: 99%

Environmental DNA recovers fish composition turnover of the coral reefs of West Indian Ocean islands

Jaquier,

Albouy,

Bach

et al. 2024

Ecology and Evolution

View full text Add to dashboard Cite

Islands have been used as model systems to study ecological and evolutionary processes, and they provide an ideal set‐up for validating new biodiversity monitoring methods. The application of environmental DNA metabarcoding for monitoring marine biodiversity requires an understanding of the spatial scale of the eDNA signal, which is best tested in island systems. Here, we investigated the variation in Actinopterygii and Elasmobranchii species composition recovered from eDNA metabarcoding along a gradient of distance‐to‐reef in four of the five French Scattered Islands in the Western Indian Ocean. We collected surface water samples at an increasing distance from reefs (0 m, 250 m, 500 m, 750 m). We used a metabarcoding protocol based on the ‘teleo’ primers to target marine reef fishes and classified taxa according to their habitat types (benthic or pelagic). We investigated the effect of distance‐to‐reef on β diversity variation using generalised linear mixed models and estimated species‐specific distance‐to‐reef effects using a model‐based approach for community data. Environmental DNA metabarcoding analyses recovered distinct fish species compositions across the four inventoried islands and variations along the distance‐to‐reef gradient. The analysis of β‐diversity variation showed significant taxa turnover between the eDNA samples on and away from the reefs. In agreement with a spatially localised signal from eDNA, benthic species were distributed closer to the reef than pelagic ones. Our findings demonstrate that the combination of eDNA inventories and spatial modelling can provide insights into species habitat preferences related to distance‐to‐reef gradients at a small scale. As such, eDNA can not only recover large compositional differences among islands but also help understand habitat selection and distribution of marine species at a finer spatial scale.

show abstract

French Territories in the Western Indian Ocean

Cited by 6 publications

References 35 publications

Coral responses to a repeat bleaching event in Mayotte in 2010

Coral responses to a repeat bleaching event in Mayotte in 2010

Peer Review #1 of "Coral responses to a repeat bleaching event in Mayotte in 2010 (v0.1)"

Environmental DNA recovers fish composition turnover of the coral reefs of West Indian Ocean islands

Contact Info

Product

Resources

About