Probes show reef risks
High temperatures are adding more stress to the Great Barrier Reef.
Australian Institute of Marine Science (AIMS) oceanographer Craig Steinberg says new technology is giving clear data on the risk of coral bleaching.
AIMS runs marine weather stations, and now an in-water autonomous robot, to monitor temperatures in real time. A network of more than 170 electronic temperature loggers is also deployed across the Reef.
“We have re-deployed an Integrated Marine Observing System (IMOS) underwater glider to areas of concern in the waters north-east of Townsville,” Mr Steinberg says.
“With its on-board sensors, the glider provides our scientists with information about ocean properties at different depths of the water column including temperature and light, to help explain any observed levels of coral bleaching.
“Knowing how deep the warm surface layer is, can help determine the depth corals are likely to experience heat stress.”
These observations provide detailed insights as to the level of bleaching now, and in context of the long-term health on the reefs AIMS has regularly surveyed for 35 years.
According to the Bureau of Meteorology, 2019 was Australia's warmest year on record. At the end of last year, sea surface temperatures were cooler than average in the Coral Sea but warmer offshore of north-western Australia. This situation has now reversed in 2020.
AIMS Chief Executive Officer Dr Paul Hardisty said the underlying trend of ocean warming means there is increased stress on Australian reefs, and an increased likelihood of bleaching in any given year.
“This year, we have come close to a major bleaching event. We are still on the knife-edge. How the reef fares will depend on weather conditions over the next few weeks. Importantly, this is happening in a non El-Niño year,” Dr Hardisty said.
“The next major El Niño event, which typically results in warmer sea temperatures on the reef at this critical time of year, poses a real risk for the reef. We need to be prepared as oceans continue to warm.
“The scale and severity of the bleaching damage in 2016 and 2017 highlighted the critical threat warming ocean temperatures pose to coral reefs.
“Coral reefs typically take a decade or more to recover from disturbances like severe bleaching events, yet they are becoming more frequent. Without a reduction of global temperatures, the health of the Reef is expected to continue to decline.”
Dr Hardisty said the weather over the next few weeks will determine if the waters in Queensland will warm further and lead to significant bleaching, or certain events would cause them to cool.