The northern and central Nice Barrier Reef have recorded their highest quantity of coral cowl for the reason that Australian Institute of Marine Science (AIMS) started monitoring 36 years in the past.
Revealed at the moment, AIMS’ Annual Abstract Report on Coral Reef Situation for 2021/22 reveals one other 12 months of elevated coral cowl throughout a lot of the Reef.
Within the 87 consultant reefs surveyed between August 2021 and Could 2022 below the AIMS Lengthy-Time period Monitoring Program (LTMP), common laborious coral cowl within the area north of Cooktown elevated to 36% (from 27% in 2021) and to 33% within the central Nice Barrier Reef (from 26% in 2021).
Nonetheless, common coral cowl within the southern area (from Proserpine to Gladstone) decreased from 38% in 2021 to 34%.
AIMS CEO Dr Paul Hardisty stated the leads to the north and central areas had been an indication the Reef might nonetheless recuperate, however the lack of coral cowl within the southern area confirmed how dynamic the Reef was.
“A 3rd of the achieve in coral cowl we recorded within the south in 2020/21 was misplaced final 12 months as a result of ongoing crown-of-thorns starfish outbreaks,” he stated.
“This reveals how weak the Reef is to the continued acute and extreme disturbances which might be occurring extra usually and are longer-lasting.”
Dr Hardisty stated the elevated frequency of mass coral bleaching occasions was “uncharted territory” for the Reef, with this 12 months’s bleaching occasion the fourth in seven years and the primary to happen throughout a La Niña.
“In our 36 years of monitoring the situation of the Nice Barrier Reef we’ve not seen bleaching occasions so shut collectively,” he stated.
“Each summer season the Reef is liable to temperature stress, bleaching and doubtlessly mortality and our understanding of how the ecosystem responds to that’s nonetheless growing.
“The 2020 and 2022 bleaching occasions, whereas intensive, did not attain the depth of the 2016 and 2017 occasions and, consequently, we’ve seen much less mortality. These newest outcomes reveal the Reef can nonetheless recuperate in intervals freed from intense disturbances.”
AIMS monitoring program group chief Dr Mike Emslie stated the 2022 outcomes constructed on the will increase in coral cowl reported for 2021, with a lot of the enhance persevering with to be pushed by fast-growing Acropora corals.
“These corals are significantly weak to wave injury, like that generated by sturdy winds and tropical cyclones,” he stated.
“They’re additionally extremely vulnerable to coral bleaching, when water temperatures attain elevated ranges, and are the popular prey for crown-of-thorns starfish. Which means massive will increase in laborious coral cowl can rapidly be negated by disturbances on reefs the place Acropora corals predominate.”
Dr Emslie stated local weather change was driving more and more frequent and longer-lasting marine heatwaves.
“The height of the newest bleaching occasion in March occurred when the gathered warmth stress triggered widespread bleaching however not intensive mortality,” he stated.
“The rising frequency of warming ocean temperatures and the extent of mass bleaching occasions highlights the crucial menace local weather change poses to all reefs, significantly whereas crown-of-thorns starfish outbreaks and tropical cyclones are additionally occurring. Future disturbance can reverse the noticed restoration in a brief period of time.”
The 36-year-long dataset of AIMS’ Lengthy-Time period Monitoring Program (LTMP) is the biggest, longest, and most complete info supply on the well being of the Nice Barrier Reef. It helps decide long-term traits within the situation of coral communities throughout the Reef.
P.c laborious coral cowl describes the proportion of the reef that’s lined in dwelling laborious coral. In 2021-22, most reefs surveyed had between 10 and 50 p.c.
Bleaching is a coral’s response to hectic situations comparable to warmth. Throughout bleaching, the coral animal loses its symbiotic algae and pigments, inflicting it to show white and doubtlessly die. Corals can survive a bleaching occasion, however they’re below extra stress.