Bacteria on Whale Skin Tell a Tale of Health and Illness
by Amy Apprill
Whales swimming in the ocean are never really alone. Even if one swims by itself with no other whales for miles around, it still has company—the tiny microbes that live on its skin. For a long time, these microbes went unnoticed or ignored. What scientists knew about skin microbes on whales was limited to studies on stranded or deceased animals, and virtually nothing was known about the microbes residing on healthy, free-ranging whales. But as links are now emerging between the microbiology of human skin and health, immunity and skin disorders, I realized that it could also be possible to learn about the health of marine mammals by studying the microbes on their skin.
We first examined the skin bacteria of North Pacific humpback whales (Megaptera novaeangliae) breeding in Hawaiian waters. Humpbacks are migratory animals that feed up north in the Arctic and make one of the longest migrations of any mammal to lower latitudes for birthing and mating. How on earth do you take a sample of their skin bacteria? Lucky for me, my marine mammal colleagues were already permitted for and skilled at collecting skin from these animals for a population genetics project. I sub-sampled skin from small biopsies already being taken for their project, and also skimmed floating skin off the ocean’s surface after whales leapt out of the water, a behavior known as breaching. Back at the laboratory, we analyzed the skin using genetic techniques focused on bacteria.
We found, to our surprise, similarities in the types of bacteria hosted by the various North Pacific humpback whales we sampled. We also observed some differences in the bacterial communities on the skin of whales that were mildly health-compromised, like those entangled in fishing gear, compared to samples from healthy whales. This implication for health was very preliminary, but still pretty exciting…
(read more: Smithsonian Ocean Portal)
photo: Wanetta Ayers