scholarly journals Ecological Vulnerability of Coral Reef Ecosystem in Wakatobi National Park During Indian Ocean Dipole Event

2020 ◽  
Vol 27 (1) ◽  
pp. 57
Author(s):  
Hawis H. Madduppa ◽  
Alan F. Koropitan ◽  
Ario Damar ◽  
Beginer Subhan ◽  
Muhammad Taufik ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Coral Reefs ◽  
Adaptive Capacity ◽  
Indian Ocean Dipole ◽  
Coral Cover ◽  
Indian Ocean Dipole Event ◽  
Ecological Vulnerability ◽  
Climate Exposure ◽  
Hard Coral Cover ◽  
Site Adaptability

This research examines coral reefs vulnerability which threatening its existences and functions by climate change. The ecological vulnerability in Wakatobi (Wangi-wangi, Kaledupa, Tomia, and Binongko) was assessed during Indian Ocean Dipole (IOD) event in 2016. Climate exposure was determined using sea surface temperature, chlorophyll-a concentration, and wind speed magnitude; sensitivity was determined using coral susceptibility, fish susceptibility, and macroalgae primary productivity rate; then adaptive capacity was developed by hard coral cover, coral size distribution, coral richness, fish biomass, herbivore diversity, and herbivore grazing relative to algal production. The values of Exposure, Sensitivity, and Adaptive capacity in Wakatobi were 0.93±0.02, 0.42±0.18, and 0.44±0.10, respectively. Site specific vulnerability scores ranged from 0.52 to 1.60 (mean 0.92±0.26). Binongko was the least vulnerable than other islands. Tomia was observed as the least adaptive capacity and Wangi-wangi was the most bleaching incidents. These results could help coral reefs monitoring priority during the event and then when the event is gone by focusing on the marked islands and sites. Sites that were observed as more vulnerable is urgently need a management strategy to overcome the vulnerability status in the future, such as increasing site adaptability.

scholarly journals A biological Indian Ocean Dipole event in 2019

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei Shi ◽  
Menghua Wang
Keyword(s):  
Biological Activity ◽  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Infrared Imaging ◽  
Equatorial Indian Ocean ◽  
The West ◽  
Indian Ocean Dipole Event ◽  
Chl A ◽  
Positive Indian Ocean Dipole ◽  
Dipole Response

AbstractThe 2019 positive Indian Ocean Dipole (IOD) event in the boreal autumn was the most serious IOD event of the century with reports of significant sea surface temperature (SST) changes in the east and west equatorial Indian Ocean. Observations of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) between 2012 and 2020 are used to study the significant biological dipole response that occurred in the equatorial Indian Ocean following the 2019 positive IOD event. For the first time, we propose, identify, characterize, and quantify the biological IOD. The 2019 positive IOD event led to anomalous biological activity in both the east IOD zone and west IOD zone. The average chlorophyll-a (Chl-a) concentration reached over ~ 0.5 mg m−3 in 2019 in comparison to the climatology Chl-a of ~ 0.3 mg m−3 in the east IOD zone. In the west IOD zone, the biological activity was significantly depressed. The depressed Chl-a lasted until May 2020. The anomalous ocean biological activity in the east IOD zone was attributed to the advection of the higher-nutrient surface water due to enhanced upwelling. On the other hand, the dampened ocean biological activity in the west IOD zone was attributed to the stronger convergence of the surface waters than that in a normal year.

Inter-basin and Multi-time Scale Interactions in generating the 2019 Extreme Indian Ocean Dipole

2021 ◽  
pp. 1-39
Author(s):  
Lei Zhang ◽  
Weiqing Han ◽  
Zeng-Zhen Hu
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Intraseasonal Oscillation ◽  
Tropical Indian Ocean ◽  
Forecast Model ◽  
Tropical Pacific ◽  
Boreal Summer ◽  
Indian Ocean Dipole Event ◽  
Easterly Wind ◽  
Western Tropical Pacific

AbstractAn unprecedented extreme positive Indian Ocean Dipole event (pIOD) occurred in 2019, which has caused widespread disastrous impacts on countries bordering the Indian Ocean, including the East African floods and vast bushfires in Australia. Here we investigate the causes for the 2019 pIOD by analyzing multiple observational datasets and performing numerical model experiments. We find that the 2019 pIOD is triggered in May by easterly wind bursts over the tropical Indian Ocean associated with the dry phase of the boreal summer intraseasonal oscillation, and sustained by the local atmosphere-ocean interaction thereafter. During September-November, warm sea surface temperature anomalies (SSTA) in the central-western tropical Pacific further enhance the Indian Ocean’s easterly winds, bringing the pIOD to an extreme magnitude. The central-western tropical Pacific warm SSTA is strengthened by two consecutive Madden Julian Oscillation (MJO) events that originate from the tropical Indian Ocean. Our results highlight the important roles of cross-basin and cross-timescale interactions in generating extreme IOD events. The lack of accurate representation of these interactions may be the root for a short lead time in predicting this extreme pIOD with a state-of-the-art climate forecast model.

scholarly journals New Scales to Guide the Assessment of Hard Coral Cover and Diversity in the Philippines

2020 ◽  
pp. 121-126
Keyword(s):  
Ecosystem Services ◽  
Coral Reefs ◽  
Coral Cover ◽  
Rapid Identification ◽  
The Philippines ◽  
Hard Coral ◽  
Hard Coral Cover ◽  
Assessment Scales

Coral reefs supply vital ecosystem services to the Philippines. Safeguarding these services requires the rapid identification of reefs that provide most services, and identification is best made by measuring hard coral cover and diversity and using updated and locally relevant assessment scales on these measurements. The use of these assessment scales has advantages and is recommended to update and improve Philippine laws.

Role of a Cyclonic Eddy in the 7000-Year-Old Mentawai Coral Reef Death During the 1997 Indian Ocean Dipole Event

2010 ◽  
Vol 7 (2) ◽  
pp. 296-300 ◽  
Author(s):  
P R C Rahul ◽  
P S Salvekar ◽  
B K Sahu ◽  
Shailesh Nayak ◽  
T Srinivas Kumar
Keyword(s):  
Coral Reef ◽  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Cyclonic Eddy ◽  
Indian Ocean Dipole Event

A Unique Feature of the 2019 Extreme Positive Indian Ocean Dipole Event

2020 ◽  
Vol 47 (18) ◽  
Author(s):  
Guojian Wang ◽  
Wenju Cai ◽  
Kai Yang ◽  
Agus Santoso ◽  
Toshio Yamagata
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Unique Feature ◽  
Indian Ocean Dipole Event ◽  
Positive Indian Ocean Dipole

scholarly journals ­Inshore, turbid coral reefs from northwest Borneo exhibiting low diversity, but high cover show evidence of resilience to various environmental stressors

2018 ◽  
Author(s):  
Christina Brown ◽  
Nicola Browne ◽  
Jennifer L McIlwain ◽  
Jens Zinke
Keyword(s):  
Coral Reefs ◽  
Coral Cover ◽  
Synergistic Effects ◽  
Coral Disease ◽  
Sediment Accumulation ◽  
Land Development ◽  
Direct Result ◽  
Wet Season ◽  
Mucus Production ◽  
Hard Coral Cover

For reefs in SE Asia the synergistic effects of rapid land-development, insufficient environmental policies and a lack of enforcement has led to poor water quality and compromised coral health from increased sediment and pollution. Those inshore turbid coral reefs, subject to significant sediment inputs, may also inherit some resilience to the effects of thermal stress and coral bleaching. We studied the inshore turbid reefs near Miri, in northwest Borneo, through a comprehensive assessment of coral cover, health and function in addition to quantifying sediment-related parameters. Although Miri Reefs had comparatively low coral species diversity, dominated by massive and encrusting forms of Diploastrea, Porites, Montipora, Favites, Dipsastrea and Pachyseris, they were characterised by a healthy cover ranging from 22-39%. We found a strong inshore to offshore gradient in hard coral cover, diversity and community composition as a direct result of spatial differences in sediment but over scales of <10 km. As well as distance to shore, we included other environmental variables like reef depth and sediment accumulation/size that explained 62.5% of variation in benthic composition among sites. None of the reefs showed evidence of coral disease and relatively low prevalence of compromised health signs including bleaching (6.7%), bioerosion (6.6%), pigmentation (2.2%), scars (1.1%) and mucus production (0.5%). There were, however, seasonal differences in bioerosion rates which increased five-fold after the 2017 wet season. Tagged colonies of Diploastrea and Pachyseries showing partial bleaching in 2016, had fully recovered by 90-100% the following year. Differences in measures of coral function like that of symbiont density and chlorophyll a for Montipora, Pachyseris and Acropora were not detected among sites. This study provides further evidence that turbid coral reefs exposed to seasonally elevated sediment loads can exhibit relatively high coral cover and be resilient to disease and elevated sea surface temperatures.

scholarly journals KONDISI TERUMBU KARANG PADA KAWASAN WISATA PANTAI MALALAYANG KOTA MANADO PROVINSI SULAWESI UTARA DENGAN MENGGUNAKAN METODE UNDERWATER PHOTO TRANSECT

2021 ◽  
Vol 9 (1) ◽  
pp. 44
Author(s):  
Devidson Daud ◽  
Joshian N. W. Schaduw ◽  
Chatrien Luzianna Sinjal ◽  
Janny D Kusen ◽  
Erli Y Kaligis ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Coral Cover ◽  
Computer Software ◽  
Digital Camera ◽  
Hard Coral ◽  
Software Technology ◽  
Technological Developments ◽  
Moderate Condition ◽  
Hard Coral Cover

Coral reefs are coastal ecosystems with the highest level of diversity with around one million species worldwide. Corals are invertebrates belonging to the Phylum Coelenterate (hollow animals) or Cnidaria. The Underwater Photo Transect (UPT) method is a method that utilizes technological developments, both digital camera technology and computer software technology. Capturing data in the field in the form of underwater photos carried out by shooting using a Canon G-16 camera equipped with a waterproof protector (housing). In this study it can be seen that the percentage of hard corals at point 1 is in the medium category, point 2 is in the medium category, and point 3 is in the bad category with the percentage of hard coral cover as follows: point 1 (one) 29.75%, point 2 (two) 31.16%, and point 3 (three) 24.26%, of the three points can represent the overall condition of the coral reefs in Malalayang Beach which is in moderate condition with a percentage of 28.39%.Keywords: Malalayang Beach, Coral Reef, UPT, CPCe

scholarly journals Phytoplankton blooms induced/sustained by cyclonic eddies during the Indian Ocean Dipole event of 1997 along the southern coasts of Java and Sumatra

2008 ◽  
Vol 5 (5) ◽  
pp. 3905-3918 ◽  
Author(s):  
P. Rahul Chand Reddy ◽  
P. S. Salvekar
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
State Of The Art ◽  
Sea Surface ◽  
Phytoplankton Blooms ◽  
Indian Ocean Dipole Event ◽  
Indonesian Archipelago ◽  
The Indian Ocean ◽  
The Tropics ◽  
Sst Anomalies

Abstract. The Indonesian archipelago is the gateway in the tropics connecting two oceans (Pacific and the Indian Ocean) and two continents (Asia and Australia). During the Indian Ocean Dipole 1997, record anomalous and unanticipated upwelling had occurred along the southern coasts of Java and Sumatra causing massive phytoplankton blooms. But the method/mode/process for such anomalous upwelling was not known. Using monthly SeaWifs chlorophyll-a anomalies, TOPEX Sea Surface Height (SSH) anomalies, Sea Surface Temperatures (SST) and currents from a state-of-the-art OGCM, we report the presence of a series of cyclonic eddies along southern coasts of Sumatra and Java during November, December 1997 and January 1998. Upwelling caused by these cyclonic eddies, as also supported by the SSH and SST anomalies, has been responsible for the phytoplankton blooms to persist and dissipate during the 3 months (November, December 1997 and January 1998).

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