Trace me if you can: Studying the marine top predators with biogeochemical markers

Deciphering the diet and major migratory movements  

An intrinsic biogeochemical marker is, according to González-Solís, a tracer, that is, “a chemical that is incorporated in animal tissues, mainly through the consumption of food, in a predictable way, such as some stable isotopes, trace elements, lipids and even contaminants. All these substances leave a chemical fingerprint in biological tissues. In this sense, all of them can be used to trace the trophic ecology and migratory movements of marine organisms over space and time.”

The various aspects of animal ecology are usually studied using samples of diet or placing devices to track movement in animals, such as satellite transmitters. Biogeochemical markers, by contrast, may not provide taxonomic detail or geographic accuracy, but tracers are not hampered by biases and constraints of the conventional approaches. Other advantages are that analyses of tracers can be conducted on any species, subsequent animal recovery is not required and results provide information about movements and past locations, as well as insights into the animals’ diet in previous areas. 

Improving strategies to conserve biodiversity  

The use of tracers in animal ecology has increased over the last decade, due to their interest in fields such as the protection and conservation of biodiversity. However, we still have insufficient knowledge on, for example, the way tracers are integrated in the tissues. According to experts, in the future research efforts will have to go on to be able to face a major challenge: deciphering in the correct way the information these traces can give us. “There are many factors that can influence the dynamics of these tracers in the biological tissues. If we do not fully understand these processes, we may take the wrong message”, warns González-Solís.