Vulnerability to collapse of coral reef ecosystems in the Western Indian Ocean

Obura, David; Gudka, Mishal; Samoilys, Melita; Osuka, Kennedy; Mbugua, James; Keith, David A.; Porter, Sean; Roche, Ronan; Hooidonk, Ruben van; Ahamada, Said; Araman, Armindo; Karisa, Juliet; Komakoma, John; Madi, Mouchtadi; Ravinia, Isabelle; Razafindrainibe, Haja; Yahya, Saleh; Zivane, Francisco

doi:10.1038/s41893-021-00817-0

Cited by 47 publications

(64 citation statements)

References 74 publications

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“…The world's coral reef ecosystems have been profoundly affected by human activities (1)(2)(3)(4)(5)(6)(7)(8). In particular, global warming has markedly increased the frequency and severity of coral bleaching events (6,9,10), outbreaks of coral disease (11), and cyclones (12).…”

Section: Introductionmentioning

confidence: 99%

Volatility in coral cover erodes niche structure, but not diversity, in reef fish assemblages

et al. 2022

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The world’s coral reefs are experiencing increasing volatility in coral cover, largely because of anthropogenic environmental change, highlighting the need to understand how such volatility will influence the structure and dynamics of reef assemblages. These changes may influence not only richness or evenness but also the temporal stability of species’ relative abundances (temporal beta-diversity). Here, we analyzed reef fish assemblage time series from the Great Barrier Reef to show that, overall, 75% of the variance in abundance among species was attributable to persistent differences in species’ long-term mean abundances. However, the relative importance of stochastic fluctuations in abundance was higher on reefs that experienced greater volatility in coral cover, whereas it did not vary with drivers of alpha-diversity. These findings imply that increased coral cover volatility decreases temporal stability in relative abundances of fishes, a transformation that is not detectable from static measures of biodiversity.

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Section: Introductionmentioning

confidence: 99%

Volatility in coral cover erodes niche structure, but not diversity, in reef fish assemblages

et al. 2022

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“…This separation of Comoros from eastern Africa differs from the ecoregions based on hermatypic corals [22,24]. These intraregional differences are relevant in coral reef threat assessments and informed the recent IUCN Red Listing of Ecosystems process for the WIO's coral reefs [81]. method: Howard Choat, Phil Heemstra, Ali Green, and Dave Bellwood.…”

Section: Discussionmentioning

confidence: 92%

Diversity of Coral Reef Fishes in the Western Indian Ocean: Implications for Conservation

Samoilys

Álvarez‐Filip

Myers³

et al. 2022

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Communities of coral reef fishes are changing due to global warming and overfishing. To understand these changes and inform conservation, knowledge of species diversity and distributions is needed. The western Indian Ocean (WIO) contains the second highest coral reef biodiversity hotspot globally, yet a detailed analysis of the diversity of coral reef fishes is lacking. This study developed a timed visual census method and recorded 356 species from 19 families across four countries in the WIO to examine patterns in species diversity. Species richness and composition differed most between the island countries of Madagascar and Comoros and both these locations differed from locations in Tanzania and Mozambique which were similar. These three regional groupings helped define WIO ecoregions for conservation planning. The highest species richness was found in Tanzania and Mozambique, and the lowest and most different species composition was found in Comoros. Biogeography explains these differences with naturally lower species diversity expected from the small, oceanic, and isolated islands of Comoros. Present day ocean currents maintain these diversity patterns and help explain the species composition in northeast Madagascar. Species distributions were driven by 46 of the 356 species; these provide guidance on important species for ongoing monitoring. The results provide a benchmark for testing future changes in reef fish species richness.

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“…According to UNESCO, coral reefs in all 29 reef-containing World Heritage sites would cease to exist as functioning ecosystems by the end of this century if greenhouse gas emissions continue to be emitted at the present rate (Elena et al 2020 ). Recent assessment of the risk of ecosystem collapse to coral reefs of the Western Indian Ocean, covering about 5% of the global total, range from critically endangered to vulnerable (Obura et al 2021 ). Coral reefs provide suitable habitat for thousands of other species, including sharks, turtles and whales.…”

Section: Impacts Of Climate Changementioning

confidence: 99%

Climate change and its impact on biodiversity and human welfare

Shivanna

2022

Proc.Indian Natl. Sci. Acad.

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Climate change refers to the long-term changes in temperature and weather due to human activities. Increase in average global temperature and extreme and unpredictable weather are the most common manifestations of climate change. In recent years, it has acquired the importance of global emergency and affecting not only the wellbeing of humans but also the sustainability of other lifeforms. Enormous increase in the emission of greenhouse gases (CO 2 , methane and nitrous oxide) in recent decades largely due to burning of coal and fossil fuels, and deforestation are the main drivers of climate change. Marked increase in the frequency and intensity of natural disasters, rise in sea level, decrease in crop productivity and loss of biodiversity are the main consequences of climate change. Obvious mitigation measures include significant reduction in the emission of greenhouse gases and increase in the forest cover of the landmass. Conference of Parties (COP 21), held in Paris in 2015 adapted, as a legally binding treaty, to limit global warming to well below 2 °C, preferably to 1.5 °C by 2100, compared to pre-industrial levels. However, under the present emission scenario, the world is heading for a 3–4 °C warming by the end of the century. This was discussed further in COP 26 held in Glasgow in November 2021; many countries pledged to reach net zero carbon emission by 2050 and to end deforestation, essential requirements to keep 1.5 °C target. However, even with implementation of these pledges, the rise is expected to be around 2.4 °C. Additional measures are urgently needed to realize the goal of limiting temperature rise to 1.5 °C and to sustain biodiversity and human welfare.

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Vulnerability to collapse of coral reef ecosystems in the Western Indian Ocean

Cited by 47 publications

References 74 publications

Volatility in coral cover erodes niche structure, but not diversity, in reef fish assemblages

Volatility in coral cover erodes niche structure, but not diversity, in reef fish assemblages

Diversity of Coral Reef Fishes in the Western Indian Ocean: Implications for Conservation

Climate change and its impact on biodiversity and human welfare

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