Group items tagged

Le blanchissement corallien : un fléau pour les petits États insulaires.

WA's SCOTT Reef has recovered from mass bleaching in 1998.

A particular species of crab has been helping Great Barrier Reef coral combat white syndrome, a deadly disease that causes coral tissue to disintegrate.

Unprecedented warm sea surface temperature (SST) anomalies were observed off the west coast of Australia in February-March 2011. Peak SST during a 2-week period were 5°C warmer than normal, causing widespread coral bleaching and fish kills. Understanding the climatic drivers of this extreme event, which we dub "Ningaloo Niño", is crucial for predicting similar events under the influence of global warming. Here we use observational data and numerical models to demonstrate that the extreme warming was mostly driven by an unseasonable surge of the poleward-flowing Leeuwin Current in austral summer, which transported anomalously warm water southward along the coast. The unusual intensification of the Leeuwin Current was forced remotely by oceanic and atmospheric teleconnections associated with the extraordinary 2010-2011 La Niña. The amplitude of the warming was boosted by both multi-decadal trends in the Pacific toward more La Niña-like conditions and intraseasonal variations in the Indian Ocean.

The third global bleaching event took its toll on Western Australia's super-corals.

Coral reefs off Tanzania's coast are being destroyed, most beyond repair.

Coral bleaching spreads to Maldives, devastating spectacular reefs.

Coral bleaching spreads to Maldives, devastating spectacular reefs.

Preliminary findings of a comprehensive scientific survey examining the impact of the climate change-related 2016 mass bleaching in the Maldives indicate that all reefs surveyed were affected by the event. Approximately 60% of all coral colonies assessed - and up to 90% in some sites - were bleached.

Preliminary findings of a comprehensive scientific survey examining the impact of the climate change-related 2016 mass bleaching in the Maldives indicate that all reefs surveyed were affected by the event. Approximately 60% of all coral colonies assessed - and up to 90% in some sites - were bleached.

In the Maldives, one of the world's lowest-lying countries, new and urgent solutions are needed to protect the islands from the impacts of climate change. Tourist resort owners and local communities are joining government authorities in efforts to make the islands more resilient.

NOAA scientists are warning that warm ocean temperatures in the tropical Pacific and Indian Oceans could set the stage for major coral bleaching events across the globe in 2015.

NOAA scientists are warning that warm ocean temperatures in the tropical Pacific and Indian Oceans could set the stage for major coral bleaching events across the globe in 2015.

Restoring coral reefs, with some help from local fish.

Restoring coral reefs, with some help from local fish.

Reef fisheries can continue to provide food and income despite corals being lost to climate change, according to new research conducted in the Seychelles.

Repeat coral bleaching caused by rising sea temperatures has resulted in lasting changes to fish communities, according to a new long-term study in the Seychelles.

When reefs decline, parrotfish thrive.

Two severe heat waves triggered coral bleaching and mass mortality in the Maldives in 1998 and 2016. Analysis of live coral cover data from 1997 to 2019 in shallow (5 m depth) reefs of the Maldives showed that the 1998 heat wave caused more than 90% of coral mortality leaving only 6.8 ± 0.3% of survived corals in all the shallow reefs investigated. No significant difference in coral mortality was observed among atolls with different levels of human pressure. Maldivian reefs needed 16 years to recover to the pre-bleaching hard coral cover values. The 2016 heat wave affected all reefs investigated, but reefs in atolls with higher human pressure showed greater coral mortality than reefs in atolls with lower human pressure. Additionally, exposed (ocean) reefs showed lower coral mortality than those in sheltered (lagoon) reefs. The reduced coral mortality in 2016 as compared to 1998 may provide some support to the Adaptive Bleaching Hypothesis (ABH) in shallow Maldivian reefs, but intensity and duration of the two heat waves were different. Analysis of coral cover data collected along depth profiles on the ocean sides of atolls, from 10 to 50 m, allowed the comparison of coral mortality at different depths to discuss the Deep Refuge Hypothesis (DRH). In the upper mesophotic zone (i.e., between 30 and 50 m), coral mortality after bleaching was negligible. However, live coral cover did not exceed 15%, a value lower than coral survival in shallow reefs. Low cover values of corals surviving in the mesophotic reefs suggest that their role as refuge or seed banks for the future recovery of some species in shallow-water reefs of the Maldives may be small. The repeatedly high coral mortality after bleaching events and the long recovery period, especially in sites with human pressure, suggest that the foreseen increased frequency of bleaching events would jeopardize the future of Maldivian reefs, and ask for reducing local pressures to improve their resilience.