scholarly journals Coral responses to a repeat bleaching event in Mayotte in 2010

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5305 ◽  
Author(s):  
David O. Obura ◽  
Lionel Bigot ◽  
Francesca Benzoni
Keyword(s):  
Coral Bleaching ◽  
Human Impacts ◽  
Linear Increase ◽  
Size Class ◽  
Sea Surface ◽  
Bleaching Event ◽  
Coral Colony ◽  
High Level ◽  
Weighting Coefficients ◽  
Coral Area

Background High sea surface temperatures resulted in widespread coral bleaching and mortality in Mayotte Island (northern Mozambique channel, Indian Ocean: 12.1°S, 45.1°E) in April–June 2010. Methods Twenty three representative coral genera were sampled quantitatively for size class distributions during the peak of the bleaching event to measure its impact. Results Fifty two percent of coral area was impacted, comprising 19.3% pale, 10.7% bleached, 4.8% partially dead and 17.5% recently dead. Acropora, the dominant genus, was the second most susceptible to bleaching (22%, pale and bleached) and mortality (32%, partially dead and dead), only exceeded by Pocillopora (32% and 47%, respectively). The majority of genera showed intermediate responses, and the least response was shown by Acanthastrea and Leptastrea (6% pale and bleached). A linear increase in bleaching susceptibility was found from small colonies (<2.5 cm, 83% unaffected) to large ones (>80 cm, 33% unaffected), across all genera surveyed. Maximum mortality in 2010 was estimated at 32% of coral area or biomass, compared to half that (16%), by colony abundance. Discussion Mayotte reefs have displayed a high level of resilience to bleaching events in 1983, 1998 and the 2010 event reported here, and experienced a further bleaching event in 2016. However, prospects for continued resilience are uncertain as multiple threats are increasing: the rate of warming experienced (0.1 °C per decade) is some two to three times less than projected warming in coming decades, the interval between severe bleaching events has declined from 16 to 6 years, and evidence of chronic mortality from local human impacts is increasing. The study produced four recommendations for reducing bias when monitoring and assessing coral bleaching: coral colony size should be measured, unaffected colonies should be included in counts, quadrats or belt transects should be used and weighting coefficients in the calculation of indices should be used with caution.

scholarly journals Kecenderungan Naiknya Suhu Permukaan Laut dan Resiliensi Karang Setelah Kejadian Pemutihan Karang 2010 dan 2016 di Taman Wisata Perairan (TWP) Pulau Pieh, Padang, Sumatra Barat

2020 ◽  
Vol 5 (1) ◽  
pp. 1
Author(s):  
Sam Wouthuyzen ◽  
Muhammad Abrar ◽  
Corry Corvianawatie ◽  
Suryo Kusumo ◽  
Yogi Yanuar ◽  
...  
Keyword(s):  
Coral Bleaching ◽  
Hot Spot ◽  
Coral Disease ◽  
High Water ◽  
Sea Surface ◽  
Bleaching Event ◽  
Marine Tourism ◽  
Average Value ◽  
West Sumatra ◽  
Almost All

<strong>Trend of Sea Surface Temperature Increase and Coral Resilience After Bleaching Events of 2010 and 2016 in The Marine Tourism Park (TWP) of Pieh Island, Padang, West Sumatra</strong>. The coral bleaching event has hit almost all of Indonesia's waters at least 4 times (in the last 34 years), which the last two events (2010 and 2016) have been discussed rather deeply. However, detailed studies in a specific location, such as in Marine Tourism Park (TWP) of Pieh Island, Padang waters, West Sumatra Province that influenced by the water mass of Indian Ocean have not yet been studied. The aim of  this paper  is to examine the trend of sea surface temperatures (SST)’s increase in the TWP of Pieh Island in 2010 and 2016 coral bleaching, and the coral resilience after the events. In this study, the long-term SST data acquired from the Aqua MODIS satellite images were used intensively.  Results show that the highest mean monthly SST called MMM that corals can be tolerated in the TWP of Pieh is 29.6 <sup>o</sup>C, higher than in all Indonesian waters (29.1 <sup>o</sup>C).The differences between the anomaly SST and the normal SST (MMM) or called Hot Spot (HS) has exceeded the average MMM in the 2010 bleaching event around 0.4-0.5 <sup>o</sup>C with its peak in April, and with alert-1 severity (Degree Heating Weeks (DHW) &lt; 8 <sup>o</sup>C-weeks; which means that the coral has partial bleaching with patchy pattern).In 2016, the HS increased by an average of 0.5 ~ 1.0 <sup>o</sup>C with peaks in January-February and May-June and with the severity of Alert-2 (DHW ≥ 8 <sup>o</sup>C-weeks, which means corals experienced severe bleaching, over wider areas, and some of corals are died). One year earlier (2015), higher HS with an average value of 0.3-0.8 <sup>o</sup>C and DHW ~ 4 <sup>o</sup>C-weeks were also observed. This indicates that coral bleaching events in the TWP of Pieh Island is repeated and occurs for long periods.The trend of increasing SST in this TWP is 0.23<sup>o</sup>C/decade, lower than in the all Indonesian waters (0.36 <sup>o</sup>C/decade). This trend shows that coral reefs in Indonesian waters including this TWP have a high resilience to recover themselves from bleaching, since the trend of increasing SST &lt; 1.0 <sup>o</sup>C/decade of the 11 coral resilience key factors, positive factors that support high coral resilience are low pollution/nutrients, low sedimentation (high water transparency), and low unfriendly of human activities, while the most negative one is the explosion of crown-of-thorns starfish, Acanthaster planci population as well as coral disease.

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

Hydrobiologia ◽  
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.

scholarly journals Extreme white colouration of frogfish Antennarius maculatus due to coral bleaching event

Coral Reefs ◽  
2016 ◽  
Vol 36 (1) ◽  
pp. 167-167 ◽  
Author(s):  
Gabriel Grimsditch ◽  
Ahmed Basheer ◽  
D. E. P. Bryant
Keyword(s):  
Coral Bleaching ◽  
Bleaching Event

scholarly journals Rapid coral mortality following unusually calm and hot conditions on Iriomote, Japan

F1000Research ◽  
2018 ◽  
Vol 6 ◽  
pp. 1728 ◽  
Author(s):  
Andrew H Baird ◽  
Sally A. Keith ◽  
Erika Woolsey ◽  
Ryuta Yoshida ◽  
Tohru Naruse
Keyword(s):  
Water Movement ◽  
Sea Surface ◽  
Bleaching Event ◽  
Coral Mortality ◽  
Average Wind Speed ◽  
Common Cause ◽  
Wind Speeds ◽  
Average Wind ◽  
The Mean ◽  
Low Wind Speeds

Coral bleaching can be induced by many different stressors, however, the most common cause of mass bleaching in the field is higher than average sea surface temperatures (SST). Here, we describe an unusual bleaching event that followed very calm sea conditions combined with higher than average SST. Patterns of mortality differed from typical bleaching in four ways: 1) mortality was very rapid; 2) a different suite of species were most affected; 3) tissue mortality in Acropora spp. was often restricted to the center of the colony; 4) the event occurred early in summer. The two weeks prior to the event included 8 days where the average wind speed was less than 3 ms-1. In addition, SSTs in the weeks preceding and during the event were 1.0-1.5°C higher than the mean for the last 30 years. We hypothesize that this unusual bleaching event was caused by anoxia resulting from a lack of water movement induced by low wind speeds combined with high SST.

Elevated sea-water temperature and solar UV-B flux associated with two successive coral mass bleaching events in Tahiti

1995 ◽  
Vol 46 (8) ◽  
pp. 1153 ◽  
Author(s):  
JH Drollet ◽  
M Faucon ◽  
PMV Martin
Keyword(s):  
Water Temperature ◽  
Coral Bleaching ◽  
Sea Water ◽  
Bleaching Event ◽  
Chemical Parameters ◽  
Physico Chemical ◽  
Long Line ◽  
Solar Uv ◽  
Line Transects ◽  
A Minor

After a minor coral bleaching event in 1993, a more dramatic episode occurred in Tahiti from March to July 1994. Coral bleaching was recorded along four continuous 25-m-long line transects. Physico-chemical parameters of the sea water (temperature, salinity, dissolved oxygen and pH) were noted once a week, and solar UV-B flux was recorded daily before and during the bleaching episode. Results emphasized the importance of the taxonomic position of coral in susceptibility to bleaching. The evolution of bleaching through time was related to mean daily solar UV-B flux and sea-water temperature. Moreover, comparison of the 1993 and 1994 data suggested temperature and/or UV-B thresholds that may elicit minor or severe bleaching events.

scholarly journals Reply to: "Tropical cirrus and water vapor: an effective Earth infrared iris feedback?"

2002 ◽  
Vol 2 (2) ◽  
pp. 99-101 ◽  
Author(s):  
M.-D. Chou ◽  
R. S. Lindzen ◽  
A. Y. Hou
Keyword(s):  
Boundary Layer ◽  
Optical Properties ◽  
Water Vapor ◽  
Surface Temperature ◽  
Climate Sensitivity ◽  
Physical Meaning ◽  
Radiative Forcing ◽  
Sea Surface ◽  
Boundary Layer Clouds ◽  
High Level

Abstract. In assessing the iris effect suggested by Lindzen et al. (2001), Fu et al. (2002) found that the response of high-level clouds to the sea surface temperature had an effect of reducing the climate sensitivity to external radiative forcing, but the effect was not as strong as LCH found. The approach of FBH to specifying longwave emission and cloud albedos appears to be inappropriate, and the derived cloud optical properties may not have real physical meaning. The cloud albedo calculated by FBH is too large for cirrus clouds and too small for boundary layer clouds, which underestimates the iris effect.

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