Sea lions as food web ambassadors
By finding out what sea lions have been eating, Lucy Jack hopes to gain insights into marine food webs and how they have changed over time.
Stable isotope analysis is being used to identify whether these apex
predators, at the top of the food chain, are eating food from a
kelp-based or coastal food web, or from a phytoplankton-based open ocean
This research will also reveal the trophic level of the
seals and sea lions (how far up the food web they are eating, and
therefore how tall the food web is). This is important because since
humans have impacted the world's oceans by fishing, marine food webs
have become shorter. By looking at changes in sea lion trophic level,
Lucy will be able to see if and when these changes have taken place,
since the arrival of humans in NZ.
Lucy gains insights into the diet of present day animals through analysis of fur samples, which should show what the animals have been eating over the last year. Samples of bones from Maori middens will show what a pre-European diet was like.
She is collecting samples from animals in Otago, Southland, Stewart Island and the Auckland Islands.