The current status of coral reefs and their vulnerability to climate change and multiple human stresses in the Comoros Archipelago, Western Indian Ocean

Cowburn, Benjamin; Samoilys, Melita; Obura, David

doi:10.1016/j.marpolbul.2018.04.065

Cited by 19 publications

(12 citation statements)

References 43 publications

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“…After the mortality caused by the 1998 bleaching event signs of recovery were observed from surveys 3 yr after the event, with coral recruits recorded at densities of 28 m 2 , the highest recorded globally at the time (Sheppard 2002;Harris and Sheppard 2008). Sheppard et al (2017) report lower densities of coral recruits in April 2017, 1 yr on from the 2016 bleaching, but the levels are still high in comparison to records from other locations (Cowburn et al 2018;Turner et al 2018). Also, modelling studies have predicted good vertical and horizontal larval connectivity in the Chagos Archipelago, which would facilitate coral recruitment and subsequent reef recovery (Riegl and Piller 2003).…”

Section: Discussionmentioning

confidence: 99%

Coral bleaching impacts from back-to-back 2015–2016 thermal anomalies in the remote central Indian Ocean

et al. 2019

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Studying scleractinian coral bleaching and recovery dynamics in remote, isolated reef systems offers an opportunity to examine impacts of global reef stressors in the absence of local human threats. Reefs in the Chagos Archipelago, central Indian Ocean, suffered severe bleaching and mortality in 2015 following a 7.5 maximum degree heating weeks (DHWs) thermal anomaly, causing a 60% coral cover decrease from 30% cover in 2012 to 12% in April 2016. Mortality was taxon specific, with Porites becoming the dominant coral genus post-bleaching because of an 86% decline in Acropora from 14 to 2% cover. Spatial heterogeneity in Acropora mortality across the Archipelago was significantly negatively correlated with variation in DHWs and with chlorophyll-a concentrations. In 2016, a 17.6 maximum DHWs thermal anomaly caused further damage, with 68% of remaining corals bleaching in May 2016, and coral cover further declining by 29% at Peros Banhos Atoll (northern Chagos Archipelago) from 14% in March 2016 to 10% in April 2017. We therefore document back-to-back coral bleaching and mortality events for two successive years in the remote central Indian Ocean. Our results indicate lower coral mortality in 2016 than 2015 despite a more severe thermal anomaly event in 2016. This could be caused by increased thermal resistance and resilience within corals surviving the 2015 thermal anomaly; however, high bleaching prevalence in 2016 suggests there remained a high sensitivity to bleaching. Similar coral mortality and community change were seen in the Chagos Archipelago following the 1998 global bleaching event, from which recovery took 10 yr. This relatively rapid recovery suggests high reef resiliency and indicates that the Archipelago's lack of local disturbances will increase the probability that the reefs will again recover over time. However, as the return time between thermal anomaly events becomes shorter, this ability to recover will become increasingly compromised. Keywords Coral bleaching Á Chagos archipelago Á Coral mortality Á British Indian Ocean Territory Á BIOT Á Coral community composition

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Section: Discussionmentioning

confidence: 99%

Coral bleaching impacts from back-to-back 2015–2016 thermal anomalies in the remote central Indian Ocean

et al. 2019

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“…Also, the issue of whether introduced seaweeds suppress coral recruitment by monopolizing settling substrate should be investigated. The WIO area has been subjected to some severe coral bleaching events (1998,2010,2016), resulting in large-scale coral mortality in shallow water areas (McClanahan et al 2007;Eriksson et al 2012;McClanahan 2017;Obura et al 2017;Cowburn et al 2018), thus opening up space for algal colonization. Recruitment is essential for the recovery of reefs, and as coral bleaching might be more frequently occurring due to climate change, factors limiting recruitment should be avoided.…”

Section: Scientific Knowledge Gaps To Address In the Wio Areamentioning

confidence: 99%

Knowledge gaps and management recommendations for future paths of sustainable seaweed farming in the Western Indian Ocean

Eggertsen

Halling

2020

Ambio

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Farming of eucheumatoid seaweeds is a widespread, promising activity and an important livelihood option in many tropical coastal areas as for example in East Africa, Western Indian Ocean (WIO). Compared to other types of aquaculture, seaweed farming has generally low impact on the environment. Nonetheless, there are potential direct or indirect negative effects of seaweed farming, such as introduction of alien species and changes in local environmental conditions. Although farming has been practiced in this region during several decades, the knowledge concerning the actual environmental impacts from faming non-native eucheumatoid haplotypes and consequently how to manage farming activities to mitigate those is highly limited. In this review, we provide a summary of the current scientific knowledge of potential direct and indirect negative environmental effects linked to eucheumatoid seaweed farming such as alterations of benthic macrophyte habitats and loss of native biodiversity. Furthermore, we highlight knowledge gaps that are of importance to address in the near future, e.g., large-scale ecosystem effects and farms as potential vectors of pathogens. We also provide a number of feasible management recommendations to be implemented for a continued development of environmentally sustainable seaweed farming practices in the WIO region, which includes spatial planning of farms to avoid sensitive areas and farming of native haplotypes of eucheumatoids instead of introduced specimens.

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“…The existing of those two island made a strait current for the regions that made quick change for water mass, also drive a lot of larvae biomass and nutrient, where this factors caused the good condition of coral reefs. The current speed is the flow of waters that drive the nutrient and organic matters for the needs of corals and zooxanthella in the photosynthesis process, larvae, and protecting the corals from the impact of sedimentation (Chacon- Gomez et al, 2013;Cowburn et al, 2018).…”

Section: Coral Reefsmentioning

confidence: 99%

Ratio of coral reefs to macroalgae: An ecosystem approach management

Ahmad

Fahrudin

Boer

et al. 2019

Depik

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The decline in the quality of coral reef ecosystems is not only caused by human activities but also caused by competition in ecosystems, including competition for space and nutrients. Research on the comparison of coral reefs with macroalgae is one of the determinants of coral reef health which is the basis for the management of coral reefs with an ecosystem approach. The purpose of this study was to analyze the comparison of coral reef cover with macroalgae. The research method used is Line Intercept Transect (LIT), the research location is 13 stations divided into 3 locations, namely north, centre, and south from Ternate Island in North Maluku. The results showed that the condition of coral reefs ranged from 24-86.60%, based on the condition categories of 13 observation locations, the coral reefs of Ternate Island were in very good condition at 15.38%, good conditions at 46.16%, adequate conditions at 30.77%, and damaged conditions 7.69%, while the condition of macroalgae cover ranged from 0-30.60% in the area of coral reef ecosystems. The ratio of the of coral reefs to algae ranges from 0 to 1.117, based on the ratio value, it is classified as low, medium to high, spread in the coral reef ecosystem of Ternate Island. Coral reef management strategies on Ternate Island include a continuous monitoring program for coral reef ecosystems, education on coral reef ecosystems, creating a conscious community of waste, and limiting the capture and restoking of herbivorous fish in coral reef areas.

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The current status of coral reefs and their vulnerability to climate change and multiple human stresses in the Comoros Archipelago, Western Indian Ocean

Cited by 19 publications

References 43 publications

Coral bleaching impacts from back-to-back 2015–2016 thermal anomalies in the remote central Indian Ocean

Coral bleaching impacts from back-to-back 2015–2016 thermal anomalies in the remote central Indian Ocean

Knowledge gaps and management recommendations for future paths of sustainable seaweed farming in the Western Indian Ocean

Ratio of coral reefs to macroalgae: An ecosystem approach management

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