Consumption by humans and marine animals impacted
University of Sidney
Research led by the University of Sydney shows that under warm
water events the nutritional balance of fish and squid changes and is of lower
quality, while under cold water events it is of higher quality.
Conducted in New Zealand, the research used a highly successful
marine predator seabird –the Australasian gannet – as a biological monitor of
the marine environment and food sources.
The team combined miniature bird-borne GPS loggers, fish and
squid nutritional analysis and nutritional modelling, and quantified colder and
warmer water events by comparing the mean sea surface temperature with 10 years
of data.
Fish and squid captured by gannets were found to have
significantly lower ratio of healthy oils to protein during warm water periods
(where sea surface temperature was warmer than the 10-year mean) and better
nutritional quality during cold water periods (lower than the 10-year mean).
Published in the Journal of Animal Ecology, the research was a collaboration between the Charles Perkins Centre, School of Life and Environment Sciences and School of Mathematics and Statistics at the University of Sydney; James Cook University in Queensland; Massey University in New Zealand; and the Ornithological Society of New Zealand.
It forms part of
the human-animal
interactions and Human Food Chain project nodes at the Charles Perkins Centre.
Lead author Dr Gabriel
Machovsky-Capuska, adjunct senior researcher at the University of
Sydney’s Charles Perkins Centre, said the findings had implications for marine life and
its predators, including humans.
Co-author Professor David
Raubenheimer, the University of Sydney’s
Leonard P Ullmann Chair in Nutritional Ecology at the School of Life and Environmental
Sciences and Charles Perkins Centre, said the research team devised a novel approach in
order to conduct the research.
“Our approach, which we call nutritional landscapes, allows us
to associate the nutritional quality of marine resources – otherwise very
challenging, as marine life continuously moves – with geographic location,
water depth and environmental conditions such as sea surface temperature and
chlorophyll levels,” Professor Raubenheimer explained.
“These findings underline the importance of linking marine
environmental fluctuations with the nutritional quality of fish and squid for
human consumption – and provide significant insights for fisheries that are
capturing fish for humans to eat.”
Dr Machovsky-Capuska said the findings were also revealing for
environmental and conservation purposes.
“The work shows that diet and foraging behaviour of marine
predators are significantly influenced by warm and cold events,” he said.
“During warm water events gannets had to work harder for their
food as they expanded their foraging habitat and increased their foraging trip
duration, while at the same time consuming prey and diets with lower content of
energy-providing oils,” he said.
“Our approach can be used to understand and ultimately protect
travelling routes for migratory species, and could support the conservation of
endangered species in terms of food quality and habitat suitability.”