scholarly journals Photo tow: a new method for estimating coral reef status and changes at large spatial scale. A coral bleaching event case study

2008 ◽  
pp. 67-74
Author(s):  
Yannick Chancerelle ◽  
Robert Maurin ◽  
Sébastien Poujade ◽  
Caroline Vieux
Keyword(s):  
Coral Reef ◽  
Spatial Scale ◽  
Coral Bleaching ◽  
New Method ◽  
Bleaching Event ◽  
Large Spatial Scale

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

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.

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

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.

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

2018 ◽  
Author(s):  
Abigail Moore ◽  
Samliok Ndobe ◽  
Jamaluddin Jompa
Keyword(s):  
Coral Reef ◽  
Coral Bleaching ◽  
Monitoring Network ◽  
Life Forms ◽  
Iucn Red List ◽  
Bleaching Event ◽  
Colour Scale ◽  
Coral Reef Ecosystems ◽  
The Caribbean ◽  
Central Sulawesi

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.

Use of NOAA Coral Reef Watch Ecoforecasts by Resource Managers During the 2014-2017 Global Coral Bleaching Event

2018 ◽  
Author(s):  
C. Mark Eakin ◽  
Gang Liu ◽  
Jacqueline De La Cour ◽  
Erick Geiger ◽  
William Skirving ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Bleaching ◽  
Bleaching Event ◽  
Resource Managers

MONITORING CORAL RECOVERY AT NEARSHORE CORAL REEFS IN PHANGNGA PROVINCE, THE ANDAMAN SEA FOLLOWING THE 2010 CORAL BLEACHING EVENT

2017 ◽  
Author(s):  
Makamas Sutthacheep ◽  
Makamas Sutthacheep ◽  
Thamasak Yeemin ◽  
Thamasak Yeemin ◽  
Sittiporn Pengsakun ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Coral Cover ◽  
Global Climate ◽  
Andaman Sea ◽  
Live Coral ◽  
Bleaching Event ◽  
Sea Star ◽  
Coral Recovery

Mass bleaching and subsequent mortality of scleractinian corals in response to elevated seawater temperatures has been considered as one of the most impacts of global climate change. Three extensive coral bleaching events in the Andaman Sea were reported, in the years 1991, 1995 and 2010. Studies on survival of coral colonies, coral recruitment and community structure of coral reef associated macrofauna would predict the trends for coral recovery from the impacts of coral bleaching events. The present study aimed to examine the status of coral communities, density of coral recruits and coral reef associated macrofauna at nearshore coral reefs in Phangnga Province, the Andaman Sea following the 2010 coral bleaching event. The dead coral cover was high (>50%) while the live coral cover was in the range of 13-21%. There was high diversity of coral recruits on natural substrates. The average densities of macrobenthic fauna varied from 1.9 to 2.6 individuals.m-2, with significant differences among study sites. The dominant macrobenthic species were a soft coral (Lobophytum sp.), a sea star (Linckia laevigata) and a sea urchin (Echinostrephus molaris). Coral recovery at these coral reefs would be possible but local anthropogenic stressors must be overwhelmingly reduced in order to enhance coral reef resilience. The long-term monitoring programs in the Andaman Sea are required for decision makers to support their adaptive management approaches.

scholarly journals Detection of Coral Reef Bleaching Based on Sentinel-2 Multi-Temporal Imagery: Simulation and Case Study

2021 ◽  
Vol 8 ◽  
Author(s):  
Jingping Xu ◽  
Jianhua Zhao ◽  
Fei Wang ◽  
Yanlong Chen ◽  
Zhongping Lee
Keyword(s):  
Remote Sensing ◽  
Coral Reef ◽  
Spatial Resolution ◽  
Water Depth ◽  
Coral Bleaching ◽  
Signal Attenuation ◽  
Change Analysis ◽  
Multi Temporal ◽  
Sentinel 2

Sentinel-2 mission has been shown to have promising applications in coral reef remote sensing because of its superior properties. It has a 5-day revisit time, spatial resolution of 10 m, free data, etc. In this study, Sentinel-2 imagery was investigated for bleaching detection through simulations and a case study over the Lizard Island, Australia. The spectral and image simulations based on the semianalytical (SA) model and the sensor spectral response function, respectively, confirmed that coral bleaching cannot be detected only using one image, and the change analysis was proposed for detection because there will be a featured change signal for bleached corals. Band 2 of Sentinel-2 is superior to its other bands for the overall consideration of signal attenuation and spatial resolution. However, the detection capability of Sentinel-2 is still limited by the water depth. With rapid signal attenuation due to the water absorption effect, the applicable water depth for bleaching detection was recommended to be less than 10 m. The change analysis was conducted using two methods: one radiometric normalization with pseudo invariant features (PIFs) and the other with multi-temporal depth invariant indices (DII). The former performed better than the latter in terms of classification. The bleached corals maps obtained using the PIFs and DII approaches had an overall accuracy of 88.9 and 57.1%, respectively. Compared with the change analysis based on two dated images, the use of a third image that recorded the spectral signals of recovered corals or corals overgrown by algae after bleaching significantly improved the detection accuracy. All the preliminary results of this article will aid in the future studies on coral bleaching detection based on remote sensing.

scholarly journals Will community calcification reflect reef accretion on future, degraded coral reefs?

2021 ◽  
Author(s):  
Coulson A. Lantz ◽  
William Leggat ◽  
Jessica L. Bergman ◽  
Alexander Fordyce ◽  
Charlotte Page ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Elevated Temperatures ◽  
Coral Cover ◽  
Coral Tissue ◽  
Bleaching Event ◽  
Bleached Coral ◽  
Coral Health ◽  
Percent Area

Abstract. Coral bleaching events continue to drive the degradation of coral reefs worldwide, causing a shift in the benthic community from coral to algae dominated ecosystems. Critically, this shift may decrease the capacity of degraded coral reef communities to maintain net positive accretion during warming-driven stress events (e.g., reef-wide coral bleaching). Here we measured rates of net ecosystem calcification (NEC) and net ecosystem production (NEP) on a degraded coral reef lagoon community (coral cover  20 %) during a reef-wide bleaching event in February of 2020 at Heron Island on the Great Barrier Reef. We found that during this bleaching event, rates of community NEP and NEC across replicate transects remained positive and did not change in response to bleaching. Repeated benthic surveys over a period of 20 d indicated an increase in the percent area of bleached coral tissue, corroborated by relatively low Symbiodiniaceae densities (~0.6 × 106 cm−2) and dark-adapted photosynthetic yields in photosystem II of corals (~0.5) sampled along each transect over this period. Given that a clear decline in coral health was not reflected in the overall community NEC estimates, it is possible that elevated temperatures in the water column that compromise coral health enhanced the thermodynamic favourability for calcification in other, ahermatypic benthic calcifiers. These data suggest that positive NEC on degraded reefs may not equate to the net positive accretion of reef structure in a future, warmer ocean. Critically, our study highlights that if coral cover continues to decline as predicted, NEC may no longer be an appropriate proxy for reef growth as the proportion of the community NEC signal owed to ahermatypic calcification increases and coral dominance on the reef decreases.

scholarly journals Ghost reefs: Nautical charts document large spatial scale of coral reef loss over 240 years

2017 ◽  
Vol 3 (9) ◽  
pp. e1603155 ◽  
Author(s):  
Loren McClenachan ◽  
Grace O’Connor ◽  
Benjamin P. Neal ◽  
John M. Pandolfi ◽  
Jeremy B. C. Jackson
Keyword(s):  
Coral Reef ◽  
Spatial Scale ◽  
Large Spatial Scale

MONITORING CORAL RECOVERY AT NEARSHORE CORAL REEFS IN PHANGNGA PROVINCE, THE ANDAMAN SEA FOLLOWING THE 2010 CORAL BLEACHING EVENT

2017 ◽  
Author(s):  
Makamas Sutthacheep ◽  
Makamas Sutthacheep ◽  
Thamasak Yeemin ◽  
Thamasak Yeemin ◽  
Sittiporn Pengsakun ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Coral Bleaching ◽  
Coral Cover ◽  
Global Climate ◽  
Andaman Sea ◽  
Live Coral ◽  
Bleaching Event ◽  
Sea Star ◽  
Coral Recovery

Mass bleaching and subsequent mortality of scleractinian corals in response to elevated seawater temperatures has been considered as one of the most impacts of global climate change. Three extensive coral bleaching events in the Andaman Sea were reported, in the years 1991, 1995 and 2010. Studies on survival of coral colonies, coral recruitment and community structure of coral reef associated macrofauna would predict the trends for coral recovery from the impacts of coral bleaching events. The present study aimed to examine the status of coral communities, density of coral recruits and coral reef associated macrofauna at nearshore coral reefs in Phangnga Province, the Andaman Sea following the 2010 coral bleaching event. The dead coral cover was high (>50%) while the live coral cover was in the range of 13-21%. There was high diversity of coral recruits on natural substrates. The average densities of macrobenthic fauna varied from 1.9 to 2.6 individuals.m-2, with significant differences among study sites. The dominant macrobenthic species were a soft coral (Lobophytum sp.), a sea star (Linckia laevigata) and a sea urchin (Echinostrephus molaris). Coral recovery at these coral reefs would be possible but local anthropogenic stressors must be overwhelmingly reduced in order to enhance coral reef resilience. The long-term monitoring programs in the Andaman Sea are required for decision makers to support their adaptive management approaches.

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