Waters Off Southern NSW A Warming Hotspot: East Australian Current Carrying More Heat South
A University of New South Wales study has found that the waters off the NSW far south coast have warmed at more than three times the global average. The study, published in Geophysical Research Letters, analysed more than 10 years of water temperature readings from five sites adjacent to the East Australian Current, combined with 25 years of satellite data. It revealed that coastal waters at Narooma, about 280 kilometres south of Sydney, have warmed an average 0.48 degrees per decade, more than double the rate of temperature rises at sites in North Stradbroke Island and Coffs Harbour.
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Nine kilometres east of Narooma is Montague Island (Baranguba), home to the largest breeding colony of little penguins in NSW. The island was the site of a five-year study by Gemma Carroll for her doctoral thesis at Macquarie University. The study looked at the impact of surface sea temperatures on the ability of little penguins to hunt for food. Their main food sources — small pelagic fish like anchovies and sardines as well as squid and krill — depend on upwellings of nutrients caused by the movement of ocean currents.
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The study of the Montague Island colony found that fluctuations in sea surface temperature had a noticeable impact on the little penguins' hunting success. " We found that offshore temperatures of about 19 to 21 degrees Celsius were optimal for the penguins," Dr Carroll said. "Above that range, the penguins weren't able to find sufficient food to meet their needs."
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"We've already seen some loss of penguin colonies in the northern part of their range, up near Coffs Harbour, we're seeing less breeding activity up there," Dr Carroll said. "Montague Island is a really fantastic place for Little Penguins to breed. "It's a kind of safe haven from predators because it's so far offshore, and we really hope that they are able to keep breeding there in the long term. "But the food availability issue is something they're going to face throughout their range on the east coast, as the EAC strengthens."
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https://www.abc.net.au/news/2021-04-03/narooma-a-global-hot-spot-for-ocean-warming-nsw-south-coast/100036384
