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A marine heatwave stuck along more than 2,000km of the Queensland coast, causing worry about the well-being of corals in the Great Barrier Reef and other marine life. Data from the US National Atmospheric and Oceanic Administration (NOAA) indicate that the heatwave began in late June, leaving about 1 million square kilometers northeast of Australia under the mercy of heatwave conditions.

The marine heatwave, defined as an occurrence whereby temperatures over an area are among the hottest 10% ever recorded for that time of year and last for at least five days, is expected to raise the risk of coral diseases and may impact fish populations, as they would need to exert more effort to find food in warmer conditions.

The Great Barrier Reef Marine Park Authority (GBRMPA) was informed of the increased ocean temperatures by the Bureau of Meteorology. Though marine heatwaves in winter typically have less dramatic effects compared to those in summer, there are still concerns that this heatwave could lead to an increase in coral diseases over the coming months.

Dr. Alex Sen Gupta, a marine heatwave expert from the UNSW Climate Change Research Centre, highlighted that global occurrences of marine heatwaves are currently at an exceptional level, causing potential impacts on marine flora and fauna due to warmer temperatures.

On her part, Dr. Jessica Stella from GBRMPA pointed out that while corals are not at risk of bleaching during this heatwave, the concern lies in a potential rise in coral diseases, as pathogens may not become dormant if the temperatures do not cool enough.

Marine biologist Prof. Jodie Rummer explained that the heatwave raises the metabolic rate of fish, increasing their need for food, thus straining the entire ecosystem.

Dr. Grant Smith from the Bureau of Meteorology reported that temperatures were more than 1°C above average for this time of year in large portions of the Great Barrier Reef and Coral Sea, with sea surface temperatures expected to remain above average until December.

Experts warned that if the reef's waters are already warmer than usual heading into summer, less additional heating would be needed to stress corals enough for them to bleach, a potentially deadly stress reaction for the animals.

Around the world, marine heatwaves are becoming more frequent and lasting longer due to climate change, and there is concern about the potential emergence of an El Niño climate pattern, which can further elevate global temperatures and increase the risk of coral bleaching. Therefore, authorities are planning for the worst-case scenario while hoping for the best. Australians are rightfully concerned about what may come their way during the upcoming summer season.