Melbourne’s little penguins adapt well to changes in the Yarra and Port Phillip Bay
Researchers have shown that Melbourne’s colony of little penguins at St Kilda are adapting remarkably well to the changing volume of flow from the Yarra River and the variable conditions in Port Phillip Bay, thanks to the penguins’ flexible foraging strategies.
The team of researchers from Monash University, in collaboration with Earthcare St Kilda and Phillip Island Nature Parks, spent the last three years tracking penguins in the Bay using GPS technology.
The team led by Monash PhD student Nicole Kowalczyk used the technology to determine the penguins’ diet, measured their reproductive success and assessed the shifting biological productivity in the Bay. They have also used valuable environmental data collected daily by the MS Spirit of Tasmania ferry on its transits of the Bay.
The colony of penguins has grown to over 1000 birds and continues to grow since its original colonisation in the 1970s of the breakwater built for the 1956 Olympic Games. The penguins have thrived despite their close proximity to the city centre of Melbourne and the intensive commercial and recreation use of Port Phillip Bay.
Ms Kowalczyk explained that the secret of the little penguins’ success partly lies in their flexible strategies for foraging in the Bay and in their ability to shift foraging areas as conditions change.
“The penguins change their foraging strategy with changes in outflow of the Yarra River,” she said. “In drought years when river outflow falls, the penguins concentrate their foraging closer to the river mouth to take advantage of the increased fish productivity resulting from nutrients carried by the Yarra. In contrast, when outflow from the Yarra increases, the penguins range more widely in the Bay to follow the dispersed nutrients and productivity.”
“Our research highlights the importance of keeping water catchments and rivers healthy, because their impact on the Bay and its inhabitants can be significant,” Associate Professor Reina said. “Penguins and many other marine animals are incredibly flexible in the face of changing environmental conditions, but they all need a healthy ecosystem in order to do well.”
Monitoring the marine environment by MS Spirit of Tasmania
To further track the penguins’ foraging areas, the researchers used environmental data collected daily by the MS Spirit of Tasmania ferry on its transits of the Bay. The Spirit is a ‘Ship of Opportunity’; part of an international program for monitoring the marine environment. Using data collected in the Bay, Ms Kowalczyk discovered a significant overlap between the Spirit’s route and the penguins’ foraging area.
“GPS tracking technology combined with the environmental data revealed that the penguins selectively forage in areas of high chlorophyll. Chlorophyll indicates the presence of the photosynthetic algae that support the entire food web. The penguins also prefer waters of less suspended sediment, because the clearer waters make it easier for them to see and hunt their fish prey,” Ms Kowalczyk said.
Associate Professor Reina said: “Environmental sampling by ‘Ships of Opportunity’ around the world makes a tremendous contribution to our detailed understanding of ocean conditions. This collaboration between merchant ships and marine scientists enables us to make discoveries such as these.”