scholarly journals Severe Heat Stress Resulted in High Coral Mortality on Maldivian Reefs following the 2015–2016 El Niño Event

Oceans ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 233-245
Author(s):  
Pia Bessell-Browne ◽  
Hannah E. Epstein ◽  
Nora Hall ◽  
Patrick Buerger ◽  
Kathryn Berry
Keyword(s):  
Heat Stress ◽  
Coral Bleaching ◽  
El Niño ◽  
El Nino ◽  
Coral Cover ◽  
Small Island ◽  
Live Coral ◽  
Dead Coral ◽  
Coral Assemblage ◽  
Severe Heat Stress

Coral cover worldwide has been declining due to heat stress caused by climate change. Here we report the impacts of the 2015–2016 El Niño mass coral bleaching event on the coral cover of reefs located on central and northern atolls of the Maldives. We surveyed six reef sites in the Alifu Alifu (Ari) and Baa (South Maalhosmadulu) Atolls using replicate 20 m benthic photo transects at two depths per reef site. Live and recently dead coral cover identified from images differed between reef sites and depth. Recently dead corals on average made up 33% of the coral assemblage at shallow sites and 24% at deep sites. This mortality was significantly lower in massive corals than in branching corals, reaching an average of only 6% compared to 41%, respectively. The best predictors of live coral cover were depth and morphology, with a greater percentage of live coral at deep sites and in massive corals. The same predictors best described the prevalence of recently dead coral, but showed inverse trends to live coral. However, there was high variability among reef sites, which could be attributed to additional local stressors. Coral bleaching and resulting coral mortalities, such as the ones reported here, are of particular concern for small island nations like the Maldives, which are reliant on coral reefs.

scholarly journals Coral bleaching in the Caramuanas reef (Todos os Santos Bay, Brazil) during the 2010 El Niño event

2017 ◽  
Vol 41 (2) ◽  
pp. 351-360
Author(s):  
Ricardo J. Miranda ◽  
Igor C.S. Cruz ◽  
Zelinda M.A.N. Leão
Keyword(s):  
Coral Bleaching ◽  
El Niño ◽  
El Nino ◽  
Coral Cover ◽  
Enso Event ◽  
Sea Surface ◽  
Live Coral ◽  
Thermal Anomalies ◽  
El Niño Event ◽  
Disease Occurrence

Episodes of coral bleaching related to El Niño events have been increasing in frequency and severity. This phenomenon is cited as a major cause of degradation of coral reefs. This study evaluates the effects of coral bleaching on the Caramuanas reef community, which occurred during the southern hemisphere summer of 2009/2010. Within this period the sea surface temperature of 31°C and thermal anomalies up to almost 1°C were recorded. During and after this El Niño event, frequency and severity of bleaching, live coral cover, number of colonies, class size, disease occurrence, and mortality rate were monitored on corals larger than 20 cm in diameter. The samples were taken at twelve fixed transects, in three reef stations. Statistical analysis showed that the severity of bleaching was different between the two periods, during and after the 2010 ENSO event. The Caramuanas reef showed sublethal bleaching effects indicating that this reef is tolerant to bleaching when the temperature anomalies do not exceed 0.75°C within one week.

scholarly journals Impact of El Niño 2015-2016 on the coral reefs of the Pacific of Costa Rica: the potential role of marine protection

2020 ◽  
Vol 68 (S1) ◽  
pp. S271-S282 ◽  
Author(s):  
Juan José Alvarado ◽  
Celeste Sánchez-Noguera ◽  
Gustavo Arias-Godínez ◽  
Tatiana Araya ◽  
Cindy Fernández-García ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
El Niño ◽  
El Nino ◽  
Coral Cover ◽  
Live Coral ◽  
El Niño Event ◽  
Live Coral Cover ◽  
The Pacific ◽  
The Impact

Introduction: El Niño 2015-2016 was considered one of the most severe worldwide, causing the third global event of coral bleaching. Previous high-intensity El Niño events (1982-83 and 1997-98) caused high coral mortalities and deterioration of coral reef structures along the Eastern Tropical Pacific, affecting both ecosystem and associated economical activities. Objective: The aim of this study was to determine the impact of the most recent El Niño event on coral reefs from Cocos Island and the Pacific coast of southern Costa Rica. Methods: Coral reefs were surveyed before (2013-2014) and after (2016) the disturbance, using underwater visual censuses within belt transects, to quantify the bottom coverage at different depths. Results: In general, average live coral cover decreased 50% after the 2015-2016 El Niño event, with Golfo Dulce being the most affected area with 75% of live coral cover decline. However, in certain localities such as Isla del Coco and Isla del Caño, the effects of El Niño were apparently minimal, since no substantial loss of live coral cover was detected. Differences in the level of deterioration found between coral reefs could be related to several factors, including the age of the protected area, the distance to centers of human population, and the effectiveness in the application of management strategies. Conclusions: The synergistic impact of the 2015-16 El Niño event and other stressors (e.g. illegal fishing and unregulated coastal human development) increased the levels of disturbance on coral reefs, threatening their structure and functioning. It is necessary to strengthen conservation strategies in order to improve the resilience of coral reefs to the impact of natural and anthropogenic disturbances. Concrete actions such as coral reef restoration, marine environmental education, and marine spatial planning must become important tools to maintain the good health of coral reefs and ensure the sustainability of the goods and services provided by these ecosystems.

Seasonal climate summary for the southern hemisphere (autumn 2017): the Great Barrier Reef experiences coral bleaching during El Niño–Southern Oscillation neutral conditions

2019 ◽  
Vol 69 (1) ◽  
pp. 310
Author(s):  
Grant A. Smith
Keyword(s):  
Western Australia ◽  
Coral Bleaching ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Maximum Temperature ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
Dry Conditions ◽  
The Mean

Austral autumn 2017 was classified as neutral in terms of the El Niño–Southern Oscillation (ENSO), although tropical rainfall and sub-surface Pacific Ocean temperature anomalies were indicative of a weak La Niña. Despite this, autumn 2017 was anomalously warm formost of Australia, consistent with the warming trend that has been observed for the last several decades due to global warming. The mean temperatures for Queensland, New South Wales, Victoria, Tasmania and South Australiawere all amongst the top 10. The mean maximum temperature for all of Australia was seventh warmest on record, and amongst the top 10 for all states but Western Australia, with a region of warmest maximum temperature on record in western Queensland. The mean minimum temperature was also above average nationally, and amongst top 10 for Queensland, Victoria and Tasmania. In terms of rainfall, there were very mixed results, with wetter than average for the east coast, western Victoria and parts of Western Australia, and drier than average for western Tasmania, western Queensland, the southeastern portion of the Northern Territory and the far western portion of Western Australia. Dry conditions in Tasmania and southwest Western Australia were likely due to a positive Southern Annular Mode, and the broader west coast and central dry conditions were likely due to cooler eastern Indian Ocean sea-surface temperatures (SSTs) that limited the supply of moisture available to the atmosphere across the country. Other significant events during autumn 2017 were the coral bleaching in the Great Barrier Reef (GBR), cyclone Debbie andmuch lower than average Antarctic sea-ice extent. Coral bleaching in the GBR is usually associated on broad scales with strong El Niño events but is becoming more common in ENSO neutral years due to global warming. The southern GBR was saved from warm SST anomalies by severe tropical cyclone Debbie which caused ocean cooling in late March and flooding in Queensland and New SouthWales. The Antarctic sea-ice extent was second lowest on record for autumn, with the March extent being lowest on record.

Successive marine heatwaves cause disproportionate coral bleaching during a fast phase transition from El Niño to La Niña

2020 ◽  
Vol 715 ◽  
pp. 136951 ◽  
Author(s):  
Steven J. Dalton ◽  
Andrew G. Carroll ◽  
Eugenia Sampayo ◽  
George Roff ◽  
Peter L. Harrison ◽  
...  
Keyword(s):  
Phase Transition ◽  
Coral Bleaching ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Fast Phase ◽  
La Nina

scholarly journals KONDISI EKOSISTEM TERUMBU KARANG DI PERAIRAN KRUENG RAYA, KABUPATEN ACEH BESAR

2021 ◽  
Vol 8 (1) ◽  
pp. 11
Author(s):  
Nurul Najmi ◽  
M Rizki Fazillah ◽  
Muhammad Agustiar
Keyword(s):  
Coral Reef ◽  
Coral Cover ◽  
Live Coral ◽  
Coral Mortality ◽  
Coral Reef Ecosystem ◽  
Dead Coral ◽  
High Increase ◽  
Mortality Index ◽  
Malacca Strait ◽  
Reef Ecosystem

This study aims to analyze the condition of the coral reef ecosystem including the substrate, genus composition, and the level of coral mortality in the waters of the Malacca Strait, Masjid Raya District, Aceh Besar District. The research was conducted from October 2016 to October 2019 in the waters of the Malacca Strait, Masjid Raya District, Aceh Besar District. The research site is divided into three stations consisting of Lhok Mee Station, Ahmad Rhang Manyang and Benteng Inong Balee Station. Data were collected using the Point Intercept Transect method. The results showed that the condition of coral reefs at Lhok Mee Station was in the damaged category with coral cover ranging from 6.56% - 13.44%. Ahmad Rhang Manyang Station is included in the moderate to good category with coral cover ranging from 38.75% - 67.19%. Meanwhile, Benteng Inong Balee Station is included in the medium category with coral cover ranging from 45.94% - 56.88%. The monitoring results found that 30 coral genera with the highest composition of the coral genera came from the Porites genus, while other coral genera were unevenly distributed. The value of the mortality index for Lhok Mee Station shows a high increase in mortality of live coral to dead coral. Meanwhile, Ahmad Rhang Manyang and Benteng Inong Balee stations have low coral mortality index values.

scholarly journals Coral microbiome diversity reflects mass coral bleaching susceptibility during the 2016 El Niño heat wave

2019 ◽  
Vol 9 (3) ◽  
pp. 938-956 ◽  
Author(s):  
Stephanie G. Gardner ◽  
Emma F. Camp ◽  
David J. Smith ◽  
Tim Kahlke ◽  
Eslam O. Osman ◽  
...  
Keyword(s):  
Heat Wave ◽  
Coral Bleaching ◽  
El Niño ◽  
El Nino ◽  
Coral Microbiome ◽  
Microbiome Diversity

Kondisi Terumbu Karang di Perairan Sisi Timur Pulau Tikus, Bengkulu

2017 ◽  
Vol 2 (2) ◽  
pp. 1
Author(s):  
Giyanto, S.Si, M.Sc
Keyword(s):  
Coral Reefs ◽  
Coral Cover ◽  
Water Clarity ◽  
Small Island ◽  
Live Coral ◽  
East Side ◽  
Water Columns ◽  
The Indian Ocean ◽  
Negative Impacts ◽  
The City

<strong>Condition of Coral Reefs in the Waters of the East Side of Tikus Island, Bengkulu. </strong> Tikus Island is located in the Province of Bengkulu. This small island is about 10 km from the City of Bengkulu. The area is only about 19,800 m2. The waters in the east side of the island was often used as location for the unloading and loading of coal from small ships into large ship (coal transhipment), to be taken to other places. This is because the condition of the port of Baai in Bengkulu is not yet possible for large ships to enter the harbour area. The study to determine the condition of coral reefs in the waters of the east side of Tikus Island was conducted in November 2012. Coral reef data collection was conducted at three stations using Line Intercept Transect (LIT). In addition, the water clarity was also measured using a Secchi disk. The results showed that the water clarity on the east side of Tikus Island was still good for coral growth, with values ranging from 9 to10 m. The percentage of live coral cover was 38.89 ± 5.02%, which was categorized as "fair". This condition was relatively better compared to several other locations that were also located in the Indian Ocean. Supporting data such as the high diversity and density of indicator fish Chaetodontidae as well as the values of heavy metal concentrations in the water columns that are still below the threshold values for marine lives, strengthen the results obtained. Regardless of the presence or absence of negative impacts of coal transhipment occurring in the waters of the east side of Tikus Island, the coral reefs were still in a normal condition. <br />

Suitability of the manta tow technique for estimating relative and absolute abundances of crown-of-thorns starfish (Acanthaster planci L. ) and corals

1992 ◽  
Vol 43 (2) ◽  
pp. 357 ◽  
Author(s):  
PJ Moran ◽  
G De'ath
Keyword(s):  
Coral Cover ◽  
Cost Effective ◽  
Live Coral ◽  
Statistical Relationship ◽  
Acanthaster Planci ◽  
Dead Coral ◽  
Effective Option ◽  
Fixed Area ◽  
Large Coral ◽  
Broad Scale

The manta tow technique has been used mainly for broad-scale surveys of large coral reef systems. The present study comprised two separate investigations of the technique. One involved investigating its repeatability by comparing the performance of three observers towed together along a reef. The other compared the counts of crown-of-thorns starfish from manta tow and SCUBA swim surveys undertaken within 30 large areas on eight reefs. Overall, the technique was found to be highly repeatable, particularly for crown-of-thorns starfish and live coral cover. It was less repeatable for assessing the cover of dead coral, although this was still within acceptable limits. A strong statistical relationship (r2adj = 0.91) was found between the starfish counts obtained from manta tows and those obtained from SCUBA swim surveys. Consequently, the former can be calibrated to predict the latter. The crown-of-thorns starfish is known to be cryptic and to have an aggregated distribution. However, the present study showed that the manta tow technique is a reasonably accurate and cost-effective option for determining relative changes in the distribution and abundance of noncryptic starfish where the unit of interest is a whole reef (or a large part thereof). As a comparison, approximately 14 manta tows (each lasting 2 min) will give the same level of accuracy as 10 SCUBA swim surveys of the same fixed area. The sensitivity of the manta tow technique in detecting relative changes in abundance will depend on the number of tows that are conducted. As a guide, however, a typical manta tow survey (involving approximately 50-60 tows) is capable of detecting a 20% change in the abundance of an out-breaking population of crown-of-thorns starfish. Given these findings, the manta tow technique also may be useful for assessing relative changes in the distribution and abundance of other organisms.

Severe, Widespread El Niño–Associated Coral Bleaching in the US Phoenix Islands

2011 ◽  
Vol 87 (3) ◽  
pp. 623-638 ◽  
Author(s):  
Bernardo Vargas-Ángel ◽  
Erin E Looney ◽  
Oliver J Vetter ◽  
Edmund F Coccagna
Keyword(s):  
Coral Bleaching ◽  
El Niño ◽  
El Nino ◽  
The Us

Relationships between boring sponge assemblages and the availability of dead coral substrate on Mexican Pacific coral reefs

2018 ◽  
Vol 99 (4) ◽  
pp. 795-805
Author(s):  
Héctor Nava ◽  
Carlos Alberto Emmanuel García-Madrigal ◽  
José Luis Carballo
Keyword(s):  
Coral Reefs ◽  
El Niño ◽  
El Nino ◽  
Potential Threat ◽  
Dead Coral ◽  
Coral Rubble ◽  
Mexican Pacific ◽  
Substrate Quality ◽  
Boring Sponge ◽  
Boring Sponges

AbstractBoring sponges are an important component of bioeroder assemblages in tropical coral reefs. They are considered as a potential threat for coral reef health, and the increase of dead corals is expected to promote their abundance. The relationship between the availability of dead coral substrata and the development of boring sponge assemblages was evaluated during El Niño 2015–16 at five reefs from Zihuatanejo, Guerrero, Mexico. Environment and substrate quality were assessed. Overall, environment conditions remained normal in relation to previous studies in the area. Only water temperature showed unusually high records at all sites and coincided with bleaching and mortality of corals, possibly caused by the effects of the El Niño event. Abundance of boring sponges in dead corals and coral rubble was lower than during previous studies. Although sponge abundance was not directly related to cover of both dead corals and coral rubble, cover of dead corals showed a high correlation with the variation in the structure of sponge assemblages across sites.Cliona vermiferadominated sponge assemblages at all sites, and its abundance was high under conditions of high cover of live corals and low cover of bleached corals. Since overall sponge abundance responded in a similar way, these results suggest that boring sponge assemblages dominated byC. vermiferaare enhanced by conditions favourable for corals. Our results imply that El Niño events in the Mexican Pacific are not likely to cause immediate population outbreaks of boring sponges.

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