![]() ![]() On the Central and Northern GBR, region-wide hard coral cover reached 33% and 36%, respectively the highest level recorded in the past 36 years of monitoring.Nearly half of the surveyed reefs (39 out of 87) had hard coral cover levels between 10% and 30%, while almost a third of the surveyed reefs (28 out of 87) had hard coral cover levels between 30% and 50%.The combination of few acute stresses and lower accumulated heat stress in 20 compared to 20 has resulted in low coral mortality and has allowed coral cover to continue to increase in the Northern and Central GBR.The number of crown-of-thorns starfish outbreaks on survey reefs has generally decreased however, there remain ongoing outbreaks on some reefs in the Southern GBR. Survey reefs experienced low levels of other acute stress over the past 12 months, with no severe cyclones impacting the Marine Park.The peak of this bleaching event was in March, and accumulated heat stress measured as Degree Heating Weeks (DHW) 1 for most of the GBR reached levels expected to result in widespread bleaching but not extensive mortality. ![]() Above-average water temperatures led to a mass coral bleaching event over the austral summer of 2021/22, the fourth event since 2016 and the first recorded during a La Niña year.In 2022, widespread recovery has led to the highest coral cover recorded by the LTMP in the Northern and Central GBR, largely due to increases in the fast-growing Acropora corals, which are the dominant group of corals on the GBR and have been largely responsible previous changes in hard coral cover.Over the past 36 years of monitoring by the Australian Institute of Marine Science (AIMS), coral reefs in the GBR have shown an ability to begin recovery after disturbances.This report summarises the condition of coral reefs of the Great Barrier Reef (GBR) from the Long-Term Monitoring Program (LTMP) surveys of 87 reefs conducted between August 2021 and May 2022 (reported as ‘2022’).The polyps can only grow in shallow warm water, less than about 30 m depth and water temperatures above about 18° C. Each coral polyp lives inside a shell of aragonite (calcium carbonate), and the shells of dead coral are eventually cemented together and covered with more calcium carbonate, from encrusting calcareous algae. Many of the present reef areas were once hills on a former coastal plain, and these became islands when the water level rose after the last Ice Age, to be colonised by coral polyps. Each reef has a thin layer of living coral capping a structure made up mainly of calcareous sand and rubble from the breakdown and consolidation of coral and other skeletal material. ![]() There are also fringing reefs on sub-tidal rock of the main coastline or continental islands. Individual reefs are of two main types: platform reefs formed from radial growths, and wall reefs resulting from elongated growths, often in areas of strong water currents. There are 500 species of seaweed, 16 species of sea snake, 1500 species of fish, and 215 bird species, plus dugong and sea turtles. The Reef comprises 400 different species of coral, 4000 different species of mollusc, and many other kinds of invertebrates. ![]()
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