Patterns of bleaching and mortality following widespread warming events in 2014 and 2015 at the Hanauma Bay Nature Preserve, Hawai‘i

Drastic increases in global carbon emissions in the past century have led to elevated sea surface temperatures that negatively affect coral reef organisms. Worldwide coral bleaching-related mortality is increasing and data has shown even isolated and protected reefs are vulnerable to the effects of global climate change. In 2014 and 2015, coral reefs in the main Hawaiian Islands (MHI) suffered up to 90% bleaching, with higher than 50% subsequent mortality in some areas. The location and severity of bleaching and mortality was strongly influenced by the spatial and temporal patterns of elevated seawater temperatures. The main objective of this research was to understand the spatial extent of bleaching mortality in Hanauma Bay Nature Preserve (HBNP), O‘ahu, Hawai‘i to gain a baseline understanding of the physical processes that influence localized bleaching dynamics. Surveys at HBNP in October 2015 and January 2016 revealed extensive bleaching (47%) and high levels of coral mortality (9.8%). Bleaching was highly variable among the four HBNP sectors and ranged from a low of ∼31% in the central bay at Channel (CH) to a high of 57% in the area most frequented by visitors (Keyhole; KH). The highest levels of bleaching occurred in two sectors with different circulation patterns: KH experienced comparatively low circulation velocity and a low temperature increase while Witches Brew (WB) and Backdoors (BD) experienced higher circulation velocity and higher temperature increase. Cumulative mortality was highest at WB (5.0%) and at BD (2.9%) although WB circulation velocity is significantly higher. HBNP is minimally impacted by local factors that can lead to decline such as high fishing pressure or sedimentation although human use is high. Despite the lack of these influences, high coral mortality occurred. Visitor impacts are strikingly different in the two sectors that experienced the highest mortality evidenced by the differences in coral cover associated with visitor use however, coral mortality was similar. These results suggest that elevated temperature was more influential in coral bleaching and the associated mortality than high circulation or visitor use.

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PERBANDINGAN TUTUPAN KARANG KERAS SEBELUM, SAAT DAN SESUDAH PEMUTIHAN KARANG DI PERAIRAN KRUENG RAYA, ACEH BESAR

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.29244/jitkt.v10i3.21974 ◽

2018 ◽

Vol 10 (3) ◽

pp. 739-745

Author(s):

Maria Ulfah ◽

Chyndy Yolanda ◽

Sofyatuddin Karina ◽

Syahrul Purnawan ◽

Sri Agustina

Keyword(s):

Mortality Rate ◽

Data Collection ◽

Coral Bleaching ◽

Coral Cover ◽

Coral Mortality ◽

Hard Coral ◽

Average Percentage ◽

Mortality Index ◽

Hard Coral Cover

ABSTRAKPenelitian ini bertujuan untuk mengetahui tutupan karang keras pada waktu sebelum (tahun 2015) saat (2016) dan sesudah pemutihan karang (2017) di Krueng Raya, Aceh Besar. Penelitian ini dilakukan pada bulan April 2017 di Krueng Raya, Aceh Besar. Pengambilan data dilakukan di 3 stasiun pengamatan menggunakan metode PIT (Point Intercept Transect) yang meliputi: Benteng Inong Balee, Ahmad Rhang Manyang, dan Lhok Mee. Hasil penelitian menunjukkan persentase rata - rata tutupan karang keras tahun 2015 sebesar 52,83% berkategori baik, tahun 2016 sebesar 32,43% berkategori sedang dan tahun pada tahun 2017 persentase tutupan karang keras menjadi 22,90% dan masuk ke dalam kategori rusak. Terdapat sebanyak 16 genus karang (2015), 18 genus karang (2016) dan 8 genus karang 8 (2017). Indeks Mortalitas (IM) tahun 2015 berkisar antara 0,02-0,20 (tingkat kematian karang yang rendah), tahun 2016 berkisar antara 0,13-0,49 (kematian karang rendah), tahun 2017 berkisar antara 0,63-0,79 (tingkat kematian karang tinggi). Hasil penelitian ini menunjukkan bahwa persentase tutupan karang keras mengalami penurunan hingga mencapai ±50% yang diakibatkan oleh pemutihan karang pada Perairan Krueng Raya Aceh Besar. ABSTRACTThe aim of this study was to determine hard coral cover at the time before (2015), during (2016) and after coral bleaching (2017) in Krueng Raya, Aceh besar. This study was conducted on April 2017 in Krueng Raya, Aceh Besar. Data collection was carried out at 3 observation stations using the PIT (Point Intercept Transect) method which included : Fort Inong Balee, Ahmad Rhang Manyang, and Lhok Mee. The results showed that the average percentage of hard coral cover in 2017 was 22.90% (bad category), it was lower than in 2016 32.43% (medium category) and in 2015 was 52.83% (good category). There were found 16 genera of coral (2015), 18 genera of coral (2016), and 8 genera of coral (2017). Mortality Index (MI) in 2015 ranged between 0.02-0.20 (low coral mortality rate), in 2016 ranged between 0.13-0.49 (low coral mortality rate), in 2017 ranged between 0.63-0.79 (high coral mortality rate). The results of this study indicate that the percentage of hard coral cover has decreased to reach 50% due to coral bleaching in the waters of Krueng Raya Aceh Besar.

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The past century of coral bleaching in the Saudi Arabian central Red Sea

PeerJ ◽

10.7717/peerj.10200 ◽

2020 ◽

Vol 8 ◽

pp. e10200

Author(s):

Thomas M. DeCarlo

Keyword(s):

Coral Reef ◽

Red Sea ◽

Coral Bleaching ◽

Saudi Arabian ◽

Outer Shelf ◽

Past Century ◽

Spatial And Temporal Patterns ◽

Late 20Th Century ◽

The Past ◽

Coral Reef Ecosystems

Accurate knowledge of the spatial and temporal patterns of coral bleaching is essential both for understanding how coral reef ecosystems are changing today and forecasting their future states. Yet, in many regions of the world, the history of bleaching is poorly known, especially prior to the late 20th century. Here, I use the information preserved within skeleton cores of long-lived Porites corals to reconstruct the past century of bleaching events in the Saudi Arabian central Red Sea. In these cores, skeletal “stress bands”—indicative of past bleaching—captured known bleaching events that occurred in 1998 and 2010, but also revealed evidence of previously unknown bleaching events in 1931, 1978, and 1982. However, these earlier events affected a significantly lesser proportion of corals than 1998 and 2010. Therefore, coral bleaching may have occurred in the central Red Sea earlier than previously recognized, but the frequency and severity of bleaching events since 1998 on nearshore reefs is unprecedented over the past century. Conversely, corals living on mid- to outer-shelf reefs have not been equally susceptible to bleaching as their nearshore counterparts, which was evident in that stress bands were five times more prevalent nearshore. Whether this pattern of susceptible nearshore reefs and resistant outer-shelf reefs continues in the future remains a key question in forecasting coral reef futures in this region.

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Differential impacts of 2016 coral bleaching on coral reef benthic communities at Sekotong Bay, Lombok Barat, Indonesia

Biodiversitas Journal of Biological Diversity ◽

10.13057/biodiv/d200237 ◽

2019 ◽

Vol 20 (2) ◽

pp. 570-575 ◽

Cited By ~ 1

Author(s):

IMAM BACHTIAR ◽

TRI ARYONO HADI

Keyword(s):

Coral Reef ◽

Coral Bleaching ◽

Soft Coral ◽

Coral Cover ◽

Benthic Communities ◽

Coral Community ◽

Coral Mortality ◽

Reef Recovery ◽

The Individual ◽

Cascade Effects

Abstract. Bachtiar I, Hadi TA. 2019. Differential impacts of 2016 coral bleaching on coral reef benthic communities at Sekotong Bay, Lombok Barat, Indonesia. Biodiversitas 20: 570-575. Coral bleaching has been a major causal factor of coral mortality worldwide in the last two decades and it is therefore threaten food security. Understanding post-bleaching recovery is therefore very crucial to formulate strategy in promoting natural coral reef recovery. The present study documented coral reef communities both in pre- and post-bleaching event in early 2016. The results show that coral bleaching variably reduced coral and soft-coral covers. Sponge and other fauna cover considerably fluctuated. Since the individual number of soft-coral, sponge and other fauna were small, there is likely no big impact of coral bleaching. Among 12 study sites, 11 sites showed significant reduction of coral cover but one site showed only little fluctuation. Overall mean reduction of coral cover was about 18%. Consequently, algal cover increased by about 24%. The present study revealed differential coral bleaching impact between outer- and inner- reefs. At outer reefs, coral community suffered more severe mass coral mortality than those at inner reefs. This disparity is likely owing to initial coral cover and species composition of the coral communities. In the second year, there is still no visible coral recruitment from larvae. Cascade effects of land-clearing and overfishing due to increasing tourism development is very likely to be additional major stress that pause post-bleaching coral reef recovery at Sekotong Bay, Lombok Island, Indonesia.

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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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Assessing population collapse of Drupella spp. (Mollusca: Gastropoda) 2 years after a coral bleaching event in the Republic of Maldives

Hydrobiologia ◽

10.1007/s10750-021-04546-5 ◽

2021 ◽

Author(s):

L. Saponari ◽

I. Dehnert ◽

P. Galli ◽

S. Montano

Keyword(s):

Coral Bleaching ◽

Prey Availability ◽

Coral Cover ◽

Environmental Data ◽

High Plasticity ◽

Bleaching Event ◽

Coral Recovery ◽

The Republic ◽

The Impact ◽

Line Intercept

AbstractCorallivory causes considerable damage to coral reefs and can exacerbate other disturbances. Among coral predators, Drupella spp. are considered as delayer of coral recovery in the Republic of Maldives, although little information is available on their ecology. Thus, we aimed to assess their population structure, feeding behaviour and spatial distribution around 2 years after a coral bleaching event in 2016. Biological and environmental data were collected using belt and line intercept transects in six shallow reefs in Maldives. The snails occurred in aggregations with a maximum of 62 individuals and exhibited a preference for branching corals. Yet, the gastropods showed a high plasticity in adapting feeding preferences to prey availability. Drupella spp. were homogenously distributed in the study area with an average of 9.04 ± 19.72 ind/200 m2. However, their occurrence was significantly different at the reef scale with the highest densities found in locations with higher coral cover. The impact of Drupella spp. appeared to be minimal with the population suffering from the loss of coral cover. We suggest that monitoring programs collect temporal- and spatial-scale data on non-outbreaking populations or non-aggregating populations to understand the dynamics of predation related to the co-occurrence of anthropogenic and natural impacts.

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Coral Reef Recovery in the Mexican Caribbean after 2005 Mass Coral Mortality—Potential Drivers

Diversity ◽

10.3390/d12090338 ◽

2020 ◽

Vol 12 (9) ◽

pp. 338

Author(s):

Xochitl E. Elías Ilosvay ◽

Ameris I. Contreras-Silva ◽

Lorenzo Alvarez-Filip ◽

Christian Wild

Keyword(s):

Coral Cover ◽

Geographical Location ◽

Relative Effect ◽

Significant Loss ◽

Coral Mortality ◽

Hard Coral ◽

Mexican Caribbean ◽

Algae Growth ◽

Reef Recovery ◽

Coral Recovery

In 2005, an extreme heatwave hit the Wider Caribbean, followed by 13 hurricanes (including hurricanes Emily and Wilma) that caused significant loss in hard coral cover. However, the drivers of the potential recovery are yet to be fully understood. Based on recent findings in the literature of coral cover recovery in the Mexican Caribbean after the mass bleaching event and associated hurricanes in 2005, this study analyzed, through random-effects meta-analysis, the hard coral and macroalgae benthic development and potential drivers of change between 2005 and 2016 in the Mexican Caribbean. Therefore, we tested the relative effect of sea surface temperature (SST), chlorophyll-a water concentration, coastal human population development, reef distance to shore, and geographical location on both hard coral and macroalgae cover over time. Findings revealed increases of both hard coral (by 6%) and algae cover (by ca. 14%, i.e., almost three times the increase of corals) over 12 years. Although our findings confirm the partial coral recovery after the 2005 Caribbean mass coral mortality event, they also indicate rapid colonization of algae across the region. Surprisingly, only SST correlated negatively with changes in coral cover. Contrary to expectations, there was a significantly greater algae cover increase in the Central section of the Mexican Caribbean, which is characterized by a low population density. However, a constant discharge of nutrient-rich freshwater may have facilitated algae growth there. This study reports partial regional reef recovery, but it also indicates that local factors, particularly eutrophication, facilitate algae growth at a speed that is much faster than coral recovery.

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Acanthaster planci impact on coral communities at permanent transect sites on Bruneian reefs, with a regional overview and a critique on outbreak causes

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315411000890 ◽

2011 ◽

Vol 92 (4) ◽

pp. 803-809 ◽

Cited By ~ 22

Author(s):

David J.W. Lane

Keyword(s):

Coral Cover ◽

Food Limitation ◽

Past Century ◽

Live Coral ◽

Sea Star ◽

Acanthaster Planci ◽

The Past ◽

Live Coral Cover ◽

Coral Communities ◽

High Precipitation

The submerged coral reefs of Brunei, little-impacted by human activity and characterized by high live coral cover, have no recorded history in recent decades of the presence of the crown-of-thorns (COT), Acanthaster planci. This sea star, first recorded on Brunei reefs in 2008, attained outbreak densities in 2010. At Littledale Shoal its impact on corals at permanent transect sites has been quantified; mean live coral cover reduced by half from 2006 to 2010 due predominantly to predation. Line intersect transect data confirm a predisposition for tabular Acropora species, a prominent feature at this site, although other scleractinian taxa were also predated. Other regional outbreaks are reviewed, including episodes, and their timing, within the neighbouring Coral Triangle (CT). Mounting evidence implicates nutrient-enhanced increases in primary production as a primary cause of COT outbreaks. However, this stands in contrast with a report of global oceanic phytoplankton decline in the past century, and there is little evidence of such a link in the CT, even though this region is characterized by high precipitation, erosional plumes and seasonal upwelling-associated phytoplankton blooms. Furthermore, until survivorship and competency for a wider spectrum of mass-spawned invertebrate planktotrophs in relation to elevated phytoplankton densities is better understood, such evidence, suggesting release from food limitation as the principal cause of enhanced COT recruitment, should be interpreted with caution.

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Coral communities condition in varying wave exposure: the gulf of Cazones, Cuba

Revista de Biología Tropical ◽

10.15517/rbt.v64i1.18231 ◽

2016 ◽

Vol 64 (1) ◽

pp. 79 ◽

Cited By ~ 3

Author(s):

Hansel Caballero Aragon ◽

Pedro M Alcolado ◽

Néstor Rey-Villiers ◽

Susana Perera Valderrama ◽

Juliett González Méndez

Keyword(s):

Species Richness ◽

Community Structure ◽

Marine Protected Area ◽

Coral Cover ◽

Coral Community ◽

Wave Exposure ◽

Maximum Diameter ◽

Live Coral ◽

Coral Mortality ◽

Coral Communities

Wave exposure can influence community structure and distribution of shallow coral reefs, by affecting organisms both directly and indirectly. To assess the current stony coral community condition under different degrees of wave exposure at a marine protected area of the Gulf of Cazones (SW Cuba), two expeditions were carried out in May 2010 and June 2012. Four sampling sites were sampled at reef crests (1.5 m deep), and twelve at fore-reefs, at 10, 15 and 20 m deep in four geographic locations. Live coral cover, species richness and composition, colony density, and maximum diameter were assessed using the AGRRA 2001 methodology. Multivariate and non-parametric statistics were applied to compare sites. The coral community structure within reef crests was not homogenous. The observed variability of indicators apparently was determined by great coral mortality events resulting from natural disturbances that occurred in the past (hurricanes, bleaching and diseases). Fore-reef coral communities displayed better condition and lower coral mortality than reef crests. Species richness and coral composition varied, while multivariate and statistical methods did not reveal site grouping with regard to wave exposure. The remaining biological condition indicators were similar among sites, except in the most exposed one, where coral cover and coral size were slightly lower. Wave exposure in the gulf of Cazones seemed not to have a significant influence on differences in condition and structure of the assessed coral communities.

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Climate Change Induced Thermal Stress Caused Recurrent Coral Bleaching over Gulf of Kachchh and Malvan Marine Sanctuary, West Coast of India

10.5772/intechopen.96806 ◽

2021 ◽

Author(s):

Mohit Arora ◽

Kalyan De ◽

Nandini Ray Chaudhury ◽

Mandar Nanajkar ◽

Prakash Chauhan ◽

...

Keyword(s):

Thermal Stress ◽

Coral Reef ◽

Coral Reefs ◽

Coral Bleaching ◽

Large Scale ◽

Heat Waves ◽

Southern Oscillation ◽

Coral Cover ◽

Imminent Threat ◽

Marginal Reefs

Coral reefs are one of the most sensitive, productive, and invaluable biological resources on the earth. However, coral reefs are facing unprecedented stress due to ongoing climate changes and intensified anthropogenic disturbances globally. Elevated Sea Surface Temperature (SST) has emerged as the most imminent threat to the thermos-sensitive reef-building corals. The 2010–2014-2016 El Niño Southern Oscillation (ENSO) caused prolonged marine heat waves (MHWs) that led to the most widespread coral bleaching and mortality in the tropical Indi-Pacific regions. Coral bleaching prediction is vital for the management of the reef biodiversity, ecosystem functioning, and services. Recent decades, satellite remote sensing has emerged as a convenient tool for large-scale coral reef monitoring programs. As thermal stress is a critical physical attribute for coral bleaching hence, the present study examines the effectiveness of the elevated SSTs as a proxy to predict coral bleaching in shallow water marginal reefs. Advanced Very High-Resolution Radiometer (AVHRR) satellite data from the NOAA Coral Reef Watch’s (CRW) platform has been used for this study. Coral bleaching indices like Bleaching Threshold (BT), Positive SST Anomaly (PA), and Degree Heating Weeks (DHW) are computed to analyze the thermal stress on the coral reefs. The computed thermal stress from satellite-derived SST data over regions concurrence with the mass coral bleaching (MCB) events. This study concludes that in the last decades (2010 to 2019) the coral cover around these regions has dramatically declined due to higher SST, which indicates that the thermal stress induced recurrent bleaching events attributed to the coral loss.

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STATUS TERUMBU KARANG DAN IKAN KARANG DI GILI MATRA, NUSA TENGGARA BARAT

ECOTROPHIC Jurnal Ilmu Lingkungan (Journal of Environmental Science) ◽

10.24843/ejes.2020.v14.i01.p02 ◽

2020 ◽

Vol 14 (1) ◽

pp. 14

Author(s):

Eghbert Elvan Ampou ◽

Suciadi Catur Nugroho ◽

Nuryani Widagti

Keyword(s):

Water Quality ◽

Coral Reef ◽

Coral Cover ◽

Reef Fishes ◽

Coral Mortality ◽

Hard Coral ◽

Mortality Index ◽

Fish Group ◽

Hard Coral Cover ◽

Reef Condition

This study aims to identify the status of reef fishes and coral reefs in Gili Meno, Air, and Trawangan or Gili Matra waters. This area is part of the North Lombok Regency, West Nusa Tenggara Province. Field observation was conducted on September 2011 at 11 (eleven) diving points. The video-transect method was used for observing the coral reef condition, while reef fishes abundance was observed by using visual-census method. The parameter that used to determine the condition of coral reef in study location are the percentage of live hard coral cover and index of coral mortality. In general, the result shows that percentage of live hard coral cover in each diving point ranged from 4.4% - 37.2% and the Coral Mortality Index (IMK) ranged form 0.40-0.92. The values describe that the condition of coral reef at eleven diving points vary from fair until poor condition. Current status of coral reef condition showed an insignificant increase from bad to moderate during the period 2011 -2018. There were 23 families of reef fishes from 46 genera were found during the study consisting of 16 genera of target fish groups, 5 genera of indicator fish group, and 25 genera of major fish group. The water quality is still within the limits of environmental quality standards. Keywords: Reef fish, coral reef, Mortality Index, water quality, Gili Matra

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