Environmental Variability and Threshold Model’s Predictions for Coral Reefs

Current models of the future of coral reefs rely on threshold (TM) and multivariate environmental variability models (VM) that vary in how they account for spatial and temporal environmental heterogeneity. Here, a VM based on General Additive Model (GAM) methods evaluated the empirical relationships between coral cover (n = 905 sites pooled to 318 reef cells of the Western and Central Indian Ocean Provinces) and 15 potentially influential variables. Six environmental and one fisheries management variables were selected as significant including SST shape distributions, dissolved oxygen, calcite, and fisheries management. Common predictive variables, including cumulative degree-heating weeks (DHW), pH, maximum light, SST bimodality and rate of rise, and two multivariate metrics were either weak or not significant predictors of coral cover. A spatially-resolved 2020 baseline for future predictions of coral cover within 11,678 reef ∼6.25 km2 cells within 13 ecoregions and 4 fisheries management categories using the 7 top VM variables was established for comparing VM and TM coral cover prediction for the year 2050. We compared the two model’s predictions for high and low Relative Concentration Pathway (CMIP5; RCP8.5 and 2.6) scenarios using the four available future-cast SST variables. The excess heat (DHW)-coral mortality relationship of the TM predicted considerably lower coral cover in 2050 than the VM. For example, for the RCP8.5 and RCP2.6 scenarios, the decline in coral for the TM predicted was 81 and 58% compared to a 29 and 20% for the VM among reef cells with >25% coral cover in 2020, if a proposed optimal fisheries management was achieved. Despite differences, coral cover predictions for the VM and TM overlapped in two environmental regions located in the southern equatorial current region of the Indian Ocean. Historical and future patterns of acute and chronic stresses are expected to be more influential than cumulative heat stress in predicting coral cover, which is better accounted for by the VM than the TM.

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New Records of Heliopora hiberniana from SE Asia and the Central Indian Ocean

Diversity ◽

10.3390/d12090328 ◽

2020 ◽

Vol 12 (9) ◽

pp. 328

Author(s):

Zoe T. Richards ◽

Leon Haines ◽

Patrick Scaps ◽

Denis Ader

Keyword(s):

Indian Ocean ◽

Coral Reefs ◽

New Records ◽

Se Asia ◽

Central Indian Ocean

Coral reefs are among the most diverse ecosystems on the planet [...]

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Ecological Vulnerability of Coral Reef Ecosystem in Wakatobi National Park During Indian Ocean Dipole Event

HAYATI Journal of Biosciences ◽

10.4308/hjb.27.1.57 ◽

2020 ◽

Vol 27 (1) ◽

pp. 57

Author(s):

Hawis H. Madduppa ◽

Alan F. Koropitan ◽

Ario Damar ◽

Beginer Subhan ◽

Muhammad Taufik ◽

...

Keyword(s):

Indian Ocean ◽

Coral Reefs ◽

Adaptive Capacity ◽

Indian Ocean Dipole ◽

Coral Cover ◽

Indian Ocean Dipole Event ◽

Ecological Vulnerability ◽

Climate Exposure ◽

Hard Coral Cover ◽

Site Adaptability

This research examines coral reefs vulnerability which threatening its existences and functions by climate change. The ecological vulnerability in Wakatobi (Wangi-wangi, Kaledupa, Tomia, and Binongko) was assessed during Indian Ocean Dipole (IOD) event in 2016. Climate exposure was determined using sea surface temperature, chlorophyll-a concentration, and wind speed magnitude; sensitivity was determined using coral susceptibility, fish susceptibility, and macroalgae primary productivity rate; then adaptive capacity was developed by hard coral cover, coral size distribution, coral richness, fish biomass, herbivore diversity, and herbivore grazing relative to algal production. The values of Exposure, Sensitivity, and Adaptive capacity in Wakatobi were 0.93±0.02, 0.42±0.18, and 0.44±0.10, respectively. Site specific vulnerability scores ranged from 0.52 to 1.60 (mean 0.92±0.26). Binongko was the least vulnerable than other islands. Tomia was observed as the least adaptive capacity and Wangi-wangi was the most bleaching incidents. These results could help coral reefs monitoring priority during the event and then when the event is gone by focusing on the marked islands and sites. Sites that were observed as more vulnerable is urgently need a management strategy to overcome the vulnerability status in the future, such as increasing site adaptability.

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Penetration of solar UVB radiation in shallow tropical waters and its potential biological effects on coral reefs; results from the central Indian Ocean and Andaman Sea

Marine Ecology Progress Series ◽

10.3354/meps144109 ◽

1996 ◽

Vol 144 ◽

pp. 109-118 ◽

Cited By ~ 60

Author(s):

RP Dunne ◽

BE Brown

Keyword(s):

Indian Ocean ◽

Coral Reefs ◽

Biological Effects ◽

Andaman Sea ◽

Uvb Radiation ◽

Tropical Waters ◽

Central Indian Ocean

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Fish predators control outbreaks of Crown-of-Thorns Starfish

Nature Communications ◽

10.1038/s41467-021-26786-8 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Frederieke J. Kroon ◽

Diego R. Barneche ◽

Michael J. Emslie

Keyword(s):

Population Dynamics ◽

Coral Reefs ◽

Fisheries Management ◽

Coral Cover ◽

Fish Biomass ◽

Effective Management ◽

Recreational Fisheries ◽

Population Outbreaks ◽

Biomass Removal ◽

Fish Predators

AbstractOutbreaks of corallivorous Crown-of-Thorns Starfish (CoTS, Acanthaster spp.) have caused persistent and widespread loss of coral cover across Indo-Pacific coral reefs. The potential drivers of these outbreaks have been debated for more than 50 years, hindering effective management to limit their destructive impacts. Here, we show that fish biomass removal through commercial and recreational fisheries may be a major driver of CoTS population outbreaks. CoTS densities increase systematically with increasing fish biomass removal, including for known CoTS predators. Moreover, the biomass of fish species and families that influence CoTS densities are 1.4 to 2.1-fold higher on reefs within no-take marine reserves, while CoTS densities are 2.8-fold higher on reefs that are open to fishing, indicating the applicability of fisheries-based management to prevent CoTS outbreaks. Designing targeted fisheries management with consideration of CoTS population dynamics may offer a tangible and promising contribution to effectively reduce the detrimental impacts of CoTS outbreaks across the Indo-Pacific.

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Geomorphology of Aldabra Atoll

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1971.0006 ◽

1971 ◽

Vol 260 (836) ◽

pp. 31-66 ◽

Cited By ~ 52

Keyword(s):

Indian Ocean ◽

Coral Reefs ◽

Sea Level ◽

Bottom Topography ◽

East African ◽

Southwest Indian Ocean ◽

Sea Floor ◽

Regional Setting ◽

The North ◽

Central Indian Ocean

1. Regional setting Aldabra Atoll (latitude 9° 24' S, longitude 46° 20' E) is situated 420 km northwest of Madagascar and 640 km from the East African mainland, in the southwest Indian Ocean (figure 1). It forms one of a group of slightly elevated coral reefs to the north of Madagascar, and is thus distinguished from the sea-level coral reefs of the Farquhar group, the Amirantes, and the central Indian Ocean. The raised reefs of Aldabra, Assumption, Cosmoledo and Astove are situated on the summits of mountains approximately 4000 m high, rising from a fairly flat sea floor between 4000 and 4300 m deep. Aldabra and Assumption cap two neighbouring peaks, which are distinct at depths shallower than 2500 m, and Cosmoledo and Astove another pair, distinct above the 2000 m level (figure 2). The general bottom topography round these islands is based on surveys by H.M.S. Owen in 1962. More detailed surveys have been made of Aldabra itself, by H.M.S. Owen in 1962 and H.M.S. Vidal in 1967, and these soundings are contoured in figure 3.

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Factors influencing microbial mat composition, distribution and dinitrogen fixation in three western Indian Ocean coral reefs

European Journal of Phycology ◽

10.1080/09670262.2011.653652 ◽

2012 ◽

Vol 47 (1) ◽

pp. 51-66 ◽

Cited By ~ 17

Author(s):

Loïc Charpy ◽

Katarzyna A. Palinska ◽

Raeid M. M. Abed ◽

Marie José Langlade ◽

Stjepko Golubic

Keyword(s):

Indian Ocean ◽

Coral Reefs ◽

Western Indian Ocean ◽

Dinitrogen Fixation ◽

Microbial Mat ◽

Composition Distribution ◽

Factors Influencing

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Nitrogen enrichment in macroalgae following mass coral mortality

Coral Reefs ◽

10.1007/s00338-021-02079-w ◽

2021 ◽

Author(s):

Eleanor J. Vaughan ◽

Shaun K. Wilson ◽

Samantha J. Howlett ◽

Valeriano Parravicini ◽

Gareth J. Williams ◽

...

Keyword(s):

Coral Reefs ◽

Coral Cover ◽

Strong Association ◽

French Polynesia ◽

Mass Mortality ◽

Transplant Experiment ◽

Bleaching Event ◽

Coral Mortality ◽

Absolute Increase ◽

Inorganic Matter

AbstractScleractinian corals are engineers on coral reefs that provide both structural complexity as habitat and sustenance for other reef-associated organisms via the release of organic and inorganic matter. However, coral reefs are facing multiple pressures from climate change and other stressors, which can result in mass coral bleaching and mortality events. Mass mortality of corals results in enhanced release of organic matter, which can cause significant alterations to reef biochemical and recycling processes. There is little known about how long these nutrients are retained within the system, for instance, within the tissues of other benthic organisms. We investigated changes in nitrogen isotopic signatures (δ15N) of macroalgal tissues (a) ~ 1 year after a bleaching event in the Seychelles and (b) ~ 3 months after the peak of a bleaching event in Mo’orea, French Polynesia. In the Seychelles, there was a strong association between absolute loss in both total coral cover and branching coral cover and absolute increase in macroalgal δ15N between 2014 and 2017 (adjusted r2 = 0.79, p = 0.004 and adjusted r2 = 0.86, p = 0.002, respectively). In Mo’orea, a short-term transplant experiment found a significant increase in δ15N in Sargassum mangarevense after specimens were deployed on a reef with high coral mortality for ~ 3 weeks (p < 0.05). We suggest that coral-derived nutrients can be retained within reef nutrient cycles, and that this can affect other reef-associated organisms over both short- and long-term periods, especially opportunistic species such as macroalgae. These species could therefore proliferate on reefs that have experienced mass mortality events, because they have been provided with both space and nutrient subsidies by the death and decay of corals.

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The Mauritius Oil Spill: What’s Next?

Pollutants ◽

10.3390/pollutants1010003 ◽

2021 ◽

Vol 1 (1) ◽

pp. 18-28

Author(s):

Davide Seveso ◽

Yohan Didier Louis ◽

Simone Montano ◽

Paolo Galli ◽

Francesco Saliu

Keyword(s):

Indian Ocean ◽

Coral Reefs ◽

Oil Spill ◽

Local Population ◽

Marine Ecosystems ◽

Mangrove Forests ◽

Biological Impact ◽

Marine Oil ◽

Restoration Techniques

In light of the recent marine oil spill that occurred off the coast of Mauritius (Indian Ocean), we comment here the incident, the containment method used by the local population, the biological impact of oil spill on two sensitive tropical marine ecosystems (coral reefs and mangrove forests), and we suggest monitoring and restoration techniques of the impacted ecosystems based on recent research advancements.

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