Novel uses for compound specific stable isotopes applied to eco-evolutionary and ecotoxicological research

A fundamental aspect of understanding ecosystems is establishing the role of individuals in their environments and for this stable isotope analysis has become a global standard.

An increasingly popular but still developing method is the analysis of nitrogen isotopes (δ15N) in specific amino acids (AA) which allows for trophic position estimates in organisms without wider sampling of their prey. This is possible because specific AAs fractionate in predictable ways through a food chain.

However, exposure to stress can change fractionation leading to incorrect ecological interpretations. We will test how δ15N in fifteen AAs change in fish exposed to environmental stress.

The hypothesis is that individuals exposed to stress will have differing fractionation rates in some AAs, violating their use as food web descriptors but allowing them to serve as novel stress biomarkers.

We will combine experimental studies on sticklebacks and cod (two populations; from the northern and southern Baltic) exposed to hypoxia and food limitation and cyanotoxins and compare to a unique multidecadal δ15N-AA cod dataset that covers periods of good and bad physiological status along with altered environmental conditions.

The proposed study lies at the forefront of ecological stable isotope research and will not only shed light on the causes behind deteriorated Baltic cod health but also contribute to understand biological stress responses on individual, population and species level.