Respiratory microbiota of humpback whales may be reduced in diversity and richness the longer they fast.

Humpback whales endure several months of fasting while undertaking one of the longest annual migrations of any mammal, which depletes the whales' energy stores and likely compromises their physiological state. Airway microbiota are linked to respiratory health in mammals. To illuminate the dynamics of airway microbiota in a physiologically challenged mammal, we investigated the bacterial communities in the blow of East Australian humpback whales at two stages of their migration: at the beginning (n = 20) and several months into their migration (n = 20), using barcoded tag sequencing of the bacterial 16S rRNA gene. We show that early in the fasting the whale blow samples had a higher diversity and richness combined with a larger number of core taxa and a different bacterial composition than later in the fasting. This study provides some evidence that the rich blow microbiota at the beginning of their fasting might reflect the whales' uncompromised physiology and that changes in the microbiota occur during the whales' migration.