Summer isn't over yet for predicted coral bleaching events

Summer isn't over yet for predicted coral bleaching events

Communities with a high cover of branching and table corals within sheltered lagoon habitats, such as at South Scott Reef, are particularly susceptible to elevated water temperatures

In October 2015, the US Federal Agency, the National Oceanic and Atmospheric Administration (NOAA) issued a warning that reefs worldwide were at high risk of widespread coral bleaching during the summer months. To date, no severe or widespread coral bleaching has been observed on reefs in Australia this austral season, however some small scale, localised bleaching has been observed.

Based on the latest NOAA Coral Reef Watch predictions, bleaching risk remains higher for reefs in Western Australia than for the Great Barrier Reef (GBR). Model projections suggest that the north western Australia region, including Scott Reef, Ashmore Reef and the Northern Kimberley, is at a higher risk for severe bleaching than the GBR.


In the West

Information regarding the bleaching risk for Western Australia is primarily gathered through NOAA satellite data on Sea Surface Temperatures (SSTs). Historically, there is good understanding of how SSTs correspond to bleaching impacts at many reefs. NOAA’s Coral Reef Watch uses this information to identify at-risk reefs. Coral Reef Watch predictions for the many coral reefs off north Western Australia are currently at “Alert Level 2,” indicating the risk of widespread bleaching is greater than 50%.

The remote nature of coral reefs off the Western Australian coast makes it difficult to monitor bleaching activity without a co-ordinated, cohesive approach. In response, a state-wide coral reef science workshop was held in November 2015 with all relevant research and management agencies in Western Australian. The key objective was to plan a strategic response to a state-wide bleaching event.

In January, AIMS researchers conducted coral bleaching baseline surveys at Scott Reef and the Rowley Shoals during the Indian Ocean Marine Research Centre (IOMRC) Joint Research Cruise, aboard the AIMS Research Vessel Solander. Oceanographic instrumentation was also deployed during the cruise by researchers from the University of Western Australia. This data will provide detailed information about local and regional variation in environmental conditions throughout the predicted bleaching period and a better understanding of the response of different corals.

These reefs will be re-surveyed in April to coincide with the forecasted bleaching event.


In the East

As of 16th February, NOAA models show that, based on current conditions, the warming threat for the Great Barrier Reef has reduced to a "Warning Level" (down from the previous "Alert Level 1"). AIMS will continue to monitor conditions over the coming weeks, however the risk of a widespread bleaching event is now less likely. 

A strong collaboration network between AIMS, James Cook University (JCU), the Bureau of Meterology (BoM), the NOAA Coral Reef Watch and the Great Barrier Reef Marine Park Authority (GBRMPA) galvanises resources and expertise to deliver a co-ordinated, efficient approach to predict, detect and monitor a large-scale bleaching event if it eventuates.

For example, satellite remote sensing and remote oceanographic instrumentation such as the AIMS weather stations provide real-time information on water temperature anomalies. This information, together with meteorological and oceanographic modelling from collaborating agencies, assists in identifying regions of the marine park that might be warming to levels that could pose a bleaching risk for corals. This information is bolstered by in-water observations recorded as part of the ‘Eye on the Reef’ program managed by the Great Barrier Reef Marine Park Authority. The program combines a number of monitoring and assessment methods to produce information on the latest reef health status and trends for management and research and will alert GBRMPA if bleaching begins to happen at regularly visited reef sites. This information is then shared with its stakeholders and partners.

AIMS will provide further information regarding coral bleaching in Australia’s tropical waters as the season progresses. Follow us on Facebook and Twitter for updates.

(Image credit for bleaching risk map: NOAA Coral Reef Watch)