How La Nina will affect reefs around the Whitsundays
THE health of the Great Barrier Reef could be impacted by regional weather patterns with La Nina set to bring a mixed bag of conditions.
A La Nina weather pattern has now formed in the tropical Pacific and will likely bring a long, wet summer.
Increased rain could be good news for the reef by cooling ocean temperatures.
However, the heightened chance of a cyclone has the potential to wreak havoc on areas of the reef.
Marine experts met this week in a meeting convened by the Great Barrier Reef Marine Park Authority to discuss these risks.
Great Barrier Reef Marine Park Authority’s chief scientist Dr David Wachenfeld said the whole picture of La Nina’s potential impact was still not clear.
“While cyclones can be damaging for coral reefs and flooding can wash pollutants into marine waters, increased rain and associated cloud cover may provide shading over the reef, cooling water temperatures,” he said.
“However, offsetting this is the global rise in ocean temperatures which is resulting in longer and more frequent marine heatwaves, such as we’ve seen on the Great Barrier Reef during the past five years.”
Dr David Wachenfeld said corals were extremely sensitive to temperature changes and it was important to try and unpack the long-range weather forecasts.
Forecasts from the Bureau of Meteorology and the US National Oceanic and Atmospheric Administration both indicate higher than average sea temperatures through December 2020 and January 2021.
While La Nina events often result in reduced ocean temperatures, thermal stress is still possible as sea surface temperatures across the whole reef have gone up because of climate change.
The workshop found it would be the regional and local weather conditions that would influence reef temperatures and therefore, whether thermal stress develops.
Australian Institute of Marine Science research program director Dr Britta Schaffelke said monitoring would be key in identifying issues.
“AIMS science teams will continue our routine long-term reef monitoring and water quality monitoring, assessing changes in reef conditions, which may result from cyclones, marine heatwaves or flooding,” she said.
“AIMS also maintain ocean moorings, reef top weather stations and sensor networks, shallow reef-based temperature loggers, and autonomous ocean gliders in partnership with the Integrated Marine Observing System.
“This reef-wide network allows us to continually monitor ocean temperatures and look at forecast models to assess the risk of marine heatwave events.”