15.10.2026 – Ocean sentinel

Cetaceans are found in every oceans of our planet and studying them help scientific communities to monitor ocean health, help to understand the entire marine ecosystem. Many marine mammals can serve as biological sentinels : their health, behaviour and population trends give early warning signs of broader marine ecosystem damage. They sit near the top of the marine food web and so they accumulate a lot of toxins from what they eat, like chemical pollutants, pesticides and so. Some variations in individual body condition can reflect changes in prey availability, food web structure, and pathogen transmission. 

Cetaceans are ecosystem engineers for our oceans: they help maintain healthy marine ecosystems by supporting biodiversity and habitat productivity. Through a process known as the “whale pump”, whales bring nutrients from deeper waters to the surface, where they release them through their feces. Nutrients such as iron and nitrogen support the growth of phytoplankton, helping sustain the marine food web and contributing to productive ocean ecosystems.

But how to study cetaceans? Different technologies are now used to understand them better and to help understand and protect our oceans better. Scientists undertake boat and aerial surveys. They use photo-identification to compare natural scars, dorsal fin shapes and fluke patterns to track individual animals over decades. Drones are used to measure body condition, assess physical health, to collect air and water droplets from a whale’s blowhole, extracting hormones, DNA, and lung microbiota. Satellite tags are also used on some animals to get more knowledge of their large-scale migratory routes, trans-oceanic geographic positions, long-term habitat use, and environmental data like water temperature and salinity.

By Juliette Colançon 

Sightings of the day

Ribeira Brava

09:00 Rough-toothed dolphin

13:00 Blainville’s beaked whale

Steno 

09:30 Rough-toothed dolphin

13:30 Rough-toothed dolphin

16:00 Atlantic spotted dolphin, Rough-toothed dolphin