Fingerprints of the Anthropocene: the 2016 Coral Bleaching Event in an Equatorial Archipelago

Coral reef ecosystems worldwide are experiencing increasingly frequent episodes of temperature-related “coral bleaching”. The Banggai Archipelago in Central Sulawesi, Indonesia, has extensive coral reefs and is home to the endemic Banggai cardinalfish, Pterapogon kauderni, a species listed as Endangered in the IUCN red List. A rapid survey was undertaken at seven sites (1.2°S-2°S) in this archipelago, in response to the national call for action during the 2016 global bleaching event. The CoralWatch method (6 point colour scale: CW1-CW6) was used; colony life-form (Global Coral Reef Monitoring Network categories) and genus (Indo-Pacific Coral-finder) were recorded. Partial and full bleaching were observed at all sites; of 1166 colonies, 64.7% were fully bleached (CW1) or very pale (CW2); with 13.5% in CW4-CW6. Water temperatures were 1-3°C above recorded maxima from 2004-2012. Branching and encrusting life-forms had the highest full/severe bleaching rates. Common genera with above average bleaching rates included Stylophora, Seriatopora, Pocillopora, Isopora, Merulina, Galaxea, some forms of Acropora and Porites. Algal overgrowth was observed on both live (fully/partially) bleached and dead colonies. Densities of Diadema sp. urchins, a key simbiont of the Banggai cardinalfish, until recently the most abundant coral reef herbivore, were extremely low (orders of magnitude less than 2004 densities), with few adult individuals present at 5/7 sites. The Caribbean experience underlines the urgency of addressing the unregulated Diadema fishery which has developed in the Banggai Archipelago since around 2007. Rehabilitating populations of this key invertebrate herbivore would contribute to biodiversity conservation and reef resilience/recovery in this equatorial archipelago.

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Detecting 2020 Coral Bleaching Event in the Northwest Hainan Island Using CoralTemp SST and Sentinel-2B MSI Imagery

Remote Sensing ◽

10.3390/rs13234948 ◽

2021 ◽

Vol 13 (23) ◽

pp. 4948

Author(s):

Bailu Liu ◽

Lei Guan ◽

Hong Chen

Keyword(s):

Coral Bleaching ◽

Large Scale ◽

Global Climate ◽

Hainan Island ◽

Threshold Value ◽

Bleaching Event ◽

Wide Range ◽

Coral Reef Ecosystems ◽

The Difference ◽

Difference Images

In recent years, coral reef ecosystems have been affected by global climate change and human factors, resulting in frequent coral bleaching events. A severe coral bleaching event occurred in the northwest of Hainan Island, South China Sea, in 2020. In this study, we used the CoralTemp sea surface temperature (SST) and Sentinel-2B imagery to detect the coral bleaching event. From 31 May to 3 October, the average SST of the study area was 31.01 °C, which is higher than the local bleaching warning threshold value of 30.33 °C. In the difference images of 26 July and 4 September, a wide range of coral bleaching was found. According to the temporal variation in single band reflectance, the development process of bleaching is consistent with the changes in coral bleaching thermal alerts. The results show that the thermal stress level is an effective parameter for early warning of large-scale coral bleaching. High-resolution difference images can be used to detect the extent of coral bleaching. The combination of the two methods can provide better support for coral protection and research.

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Early trajectories of benthic coral reef communities following the 2015/16 coral bleaching event at remote Aldabra Atoll, Seychelles

Scientific Reports ◽

10.1038/s41598-020-74077-x ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Anna Koester ◽

Valentina Migani ◽

Nancy Bunbury ◽

Amanda Ford ◽

Cheryl Sanchez ◽

...

Keyword(s):

Coral Reef ◽

Water Temperature ◽

Coral Bleaching ◽

Coral Cover ◽

Bleaching Event ◽

Hard Coral ◽

Reef Communities ◽

Remote Sites ◽

Hard Coral Cover ◽

Coral Reef Communities

Abstract Documenting post-bleaching trajectories of coral reef communities is crucial to understand their resilience to climate change. We investigated reef community changes following the 2015/16 bleaching event at Aldabra Atoll, where direct human impact is minimal. We combined benthic data collected pre- (2014) and post-bleaching (2016–2019) at 12 sites across three locations (lagoon, 2 m depth; seaward west and east, 5 and 15 m depth) with water temperature measurements. While seaward reefs experienced relative hard coral reductions of 51–62%, lagoonal coral loss was lower (− 34%), probably due to three-fold higher daily water temperature variability there. Between 2016 and 2019, hard coral cover did not change on deep reefs which remained dominated by turf algae and Halimeda, but absolute cover on shallow reefs increased annually by 1.3% (east), 2.3% (west) and 3.0% (lagoon), reaching, respectively, 54%, 68% and 93% of the pre-bleaching cover in 2019. Full recovery at the shallow seaward locations may take at least five more years, but remains uncertain for the deeper reefs. The expected increase in frequency and severity of coral bleaching events is likely to make even rapid recovery as observed in Aldabra’s lagoon too slow to prevent long-term reef degradation, even at remote sites.

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Inferences on the role of coral bleaching or seasonality on cross-habitat movement of nekton assemblages in adjacent coral reef, seagrass, and mangrove habitats

Bulletin of Marine Science ◽

10.5343/bms.2019.0024 ◽

2020 ◽

Vol 96 (3) ◽

pp. 431-448

Author(s):

Severino G Salmo ◽

John Charles A Altomonte

Keyword(s):

Coral Reef ◽

Coral Bleaching ◽

Seasonal Changes ◽

Dominant Species ◽

Environmental Parameters ◽

Bleaching Event ◽

Seasonal Fluctuations ◽

Bleached Coral ◽

Habitat Affinity

We investigated shifts in nekton assemblages in coral reef, seagrass, and mangrove habitats that coincided with a coral bleaching event in June 2016. The study was conducted in May 2016 (prebleaching), July 2016 (bleaching), October 2016 (4-mo postbleaching), and February 2017 (7-mo postbleaching) in relatively undisturbed coastal areas in Busuanga, Palawan, western Philippines. We used triangular trap nets to capture nekton samples from each habitat. In coral reef and mangrove habitats, there were increases in nekton abundance and biomass from the prebleaching to the bleaching period. After the bleaching event, however, there were reductions in nekton abundance and biomass at the coral reefs until 7-mo postbleaching. Species composition changed at all sites where shifts in dominant species, habitat affinity, and trophic category were observed. The postbleaching increase in nekton abundance in mangroves coincided with the decreased nekton abundance in the coral reef, suggesting a cross-habitat movement, likely due to the reduced suitability and/or food in the bleached coral reef. The changes in the nekton assemblage may also have been due to seasonal fluctuations in environmental parameters, especially salinity. Our study presents evidence of the possible role of coral bleaching or seasonal changes on cross-habitat movements of nekton assemblages, which can be inferred as an indicator of disturbance. The presence of adjacent vegetated habitats may provide refuge for the affected nekton assemblage of the coral reef.

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Recruitment of hard coral after coral bleaching in Krueng Raya Water, Aceh Besar

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/869/1/012043 ◽

2021 ◽

Vol 869 (1) ◽

pp. 012043

Author(s):

M Ulfah ◽

A Siswanto ◽

S Agustina ◽

S Purnawan

Keyword(s):

Coral Reef ◽

Coral Bleaching ◽

Sampling Method ◽

Systematic Sampling ◽

Hard Coral ◽

Coral Recruitment ◽

Coral Genus ◽

Study Results ◽

Coral Reef Ecosystems ◽

Systematic Sampling Method

Abstract Krueng Raya waters is an area that has a distribution of coral reef ecosystems. This study aims to determine the recruitment of hard corals after coral bleaching Krueng Raya waters, Aceh Besar District. This research was conducted in April 2017 in Krueng Raya, Aceh Besar. Data were collected at three observation stations using a systematic sampling method using a 1x1 m quadratic transect. Based on the study results, coral recruitment was obtained from eight families and 13 genera (Acropora, Cetenactis, Diploastrea, Favia, Favites, Galaxea, Goniastrea, Helliopora, Leptastrea, Montastrea, Pavona, Pocillopora, and Porites). Where the most abundant coral genus found was from the genus Pocilopora and Porites (16 coloni/10m2). while the station with the highest colony abundance was at station 3 with 28 colonies/10m2.

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One Hundred and Fifty Years of Warming on Caribbean Coral Reefs

10.1101/2021.05.12.443696 ◽

2021 ◽

Author(s):

Colleen B Bove ◽

Laura Mudge ◽

John F Bruno

Keyword(s):

Coral Reef ◽

Coral Reefs ◽

Thermal Characteristics ◽

Marine Systems ◽

Caribbean Coral ◽

Coral Reef Ecosystems ◽

Caribbean Coral Reef ◽

Caribbean Coral Reefs ◽

The Caribbean ◽

And Function

Anthropogenic climate change is rapidly altering the characteristics and dynamics of biological communities. This is especially apparent in marine systems as the world's oceans are warming at an unprecedented rate, causing dramatic changes to coastal marine systems, especially on coral reefs of the Caribbean. We used three complementary ocean temperature databases (HadISST, Pathfinder, and OISST) to quantify change in thermal characteristics of Caribbean coral reefs over the last 150 years (1871-2020). These sea surface temperature (SST) databases included combined in situ and satellite-derived SST (HadISST, OISST), as well as satellite-only observations (Pathfinder) at multiple spatial resolutions. We also compiled a Caribbean coral reef database identifying 5,326 unique reefs across the region. We found that Caribbean reefs have warmed on average by 0.20 °C per decade since 1987, the calculated year that rapid warming began on Caribbean reefs. Further, geographic variation in warming rates ranged from 0.17 °C per decade on Bahamian reefs to 0.26 °C per decade on reefs within the Southern and Eastern Caribbean ecoregions. If this linear rate of warming continues, these already threatened ecosystems would warm by an additional 1.6 °C on average by 2100. We also found that marine heatwave (MHW) events are increasing in both frequency and duration across the Caribbean. Caribbean coral reefs now experience on average 5 MHW events annually, compared to 1 per year in the early 1980s. Combined, these changes have caused a dramatic shift in the composition and function of Caribbean coral reef ecosystems. If reefs continue to warm at this rate, we are likely to lose even the remnant Caribbean coral reef communities of today in the coming decades.

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Composition of coral species and benthic organism at Tiaka Oilfield, Tolo Bay, Central Sulawesi

Tomini Journal of Aquatic Science ◽

10.37905/tjas.v1i1.5941 ◽

2020 ◽

Vol 1 (1) ◽

pp. 22-28

Author(s):

Kasim Mansyur ◽

Achmad Rizal ◽

Musayyadah Tis'in ◽

Muh Saleh Nurdin ◽

Nuke Susanti

Keyword(s):

Coral Reef ◽

Coral Species ◽

Oil Field ◽

Benthic Organism ◽

Benthic Organisms ◽

Benthic Species ◽

Visual Census ◽

Coral Reef Ecosystems ◽

Central Sulawesi ◽

Line Intercept

This research aims to find out the composition of the coral and benthic organisms at Tiaka Oilfield. This study was conducted in July 2015. Monitoring of coral and benthic organisms used line intercept transect and visual census method. The research results indicated that 16 coral species were consisting of 6 genera. Coral species dominated by the genus Acropora. Benthic organisms that live in symbiosis with coral reef ecosystems in the Tiaka Oil Field were found 11 benthic species consisting of 54 species

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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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