DNA reveals jellyfish a popular choice in albatross diet
Albatross have a taste for jellyfish, according to DNA evidence from their droppings.
Analysis of 1460 scat samples from eight sub-Antarctic breeding colonies of black-browed and Campbell albatrosses, found jellyfish DNA was present in 37% of the scats and made up 20% of the dietary DNA identified in those scats.
Seabird ecologist, Ms Julie McInnes, from the Australian Antarctic Division and Institute for Marine and Antarctic Studies (IMAS), said scientists previously considered jellyfish an unlikely menu item.
“Past studies of albatross diets relied largely on analysis of their stomach contents, with jellyfish found in less than one in five samples, and then only in low amounts of around five per cent,” Ms McInnes said.
“However, jellyfish are difficult to identify through stomach content analysis, because they are quickly digested and leave no ‘hard parts’, such as bones.”
The new research relied on a technique known as DNA metabarcoding, which enables the DNA of distinct groups of organisms to be identified within a scat sample.
The analysis identified six main prey groups, with bony fish the favoured prey item, followed by jellyfish, crustaceans and squid.
“Our results show that jellyfish are a common prey of adult black-browed and Campbell albatrosses and that they are fed to chicks,” Ms McInnes said.
“We also found that the frequency of jellyfish occurrence in the diet was similar in years of high and low jellyfish abundance, suggesting that the birds may be actively targeting jellyfish.”
The finding provides new information about the foraging ecology of the birds and will help scientists assess the health of the broader marine ecosystem into the future.
“The diets of top-order predators, such as seabirds, reflect changes in the availability of prey, due to pressures such as climate change or fishing,” Ms McInnes said
“Warmer oceans and overfishing are predicted to favour jellyfish populations, so it’s important to understand the contribution of these gelatinous organisms to the birds’ diet.
“Any future monitoring programs that use diet data should employ methods that can detect all major prey groups, so that ecosystem changes can be observed,” Ms McInnes said.
The research collaboration also included the Tasmanian Department of Primary Industries, Parks, Water and Environment, and a range of international institutions. It was published in Molecular Ecology in August.