Professor Roughan said this January could cross that mark.
David Booth, professor of marine ecology at the University of Technology Sydney, said several years ago corals bleached in the harbor when the ocean temperature hit 26 degrees, with all eyes now on towards the reaction of the coral this time.
He said it was interesting to see new species migrate, but it came at the expense of other species accustomed to cooler environments.
Professor Booth added that while marine animals that thrive in cooler ecosystems can move as warmer waters prevail, they can only travel limited distances.
“The fish may scatter further south, but they will run out of room – once they reach the end of Tasmania it’s a long way to Antarctica,” he said.
Ocean swimmer Lauren Tischendorf, who recently became the first female to swim solo around Lord Howe Island, swims regularly around the beaches in the eastern suburbs.
“I certainly noticed that in early December and late November the water was warmer than normal,” she said. “You can tell it early in the morning because it’s still cool outside, but the water is quite warm and soft.
“While this warmer water is great for swimming – you can go further without feeling cold, without needing extra nutrition and rehydration – but at the same time, it’s not as good for our environment. “
Swimmers at St Kilda Beach in Melbourne experienced sea temperatures of 21.3 degrees on Tuesday, about 0.5 degrees warmer than the monthly average, while the ocean temperature at Williamstown was 21, 6 degrees – slightly higher than its monthly average of 20.8 degrees. The hottest temperature on record in Williamstown in January was 24 degrees.