The little penguin population on Granite Island is still feeling the effects of the Millennium Drought (2001-10) according to new research from Flinders University.
The drought had major impacts on freshwater river inflows, which in turn influenced the little penguin population's main fish food source, southern garfish.
The coastal and estuarine environment at Victor Harbor, the Lower Lakes and Coorong depends on regular outflows from the mouth of the River Murray, which regularly closes during periods of drought.
The current Granite Island population has fallen to only 20 adults while all other populations in Encounter Bay are now extinct, said Flinders University expert Dr Diane Colombelli- Négrel, who coordinates annual census counts of numbers on Granite Island.
The research also suggested ocean warming and other factors - such as predation and low juvenile survival - could also have contributed to the dwindling population.
"The fact that the Granite Island little penguin population still had not recovered in 2020 - after larger river outflows in 2012-13 and at the end of 2016 - suggests that the population may have reached some critical reduction in the number of breeding birds during the drought period," The research stated.
"Given droughts are becoming more and more frequent, future studies are needed both within Australia and elsewhere to identify which species may be affected by hydrological droughts (including) for seabird conservation and river management.
"The results of this study suggest that decisions regarding river water management should consider not only human and terrestrial environmental requirements, but also the long- term impacts that this may have for the coastal environment outside the river system."
Researchers called for:
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