Micro-slices of fish scales reveal effects of dams on lungfish diet

Australian lungfish are living fossils that have survived virtually unchanged since their appearance in the fossil record 340 million years ago. They are well known to have the nifty ability to survive for several days out of water. Now, a new study uses their scales to infer what they ate over periods of more than 50 years. The new technique first ages the lungfish by measuring radioactive signatures in the scales that track radioactivity from nuclear weapons testing in the 1950s and 1960s, and then having dated micro-slices of the fish scales, each slice is examined for carbon and nitrogen isotopes that unveil their food sources throughout their life. The results show that Australian lungfish shifted from food sources on river bottoms (typical of pristine streams) to food sources found in the water column, after their rivers were dammed. In addition, their scales reveal a period when the dairy industry expanded and nitrogen fertilizer in the water increased, and then nitrogen levels declined again as diary pastures dwindled. The new research was led by SAFS professor Julian Olden, and is published in River Research and Applications.

Back to Top