A microbiome refers to all the microscopic organisms (bacteria, fungi, and other tiny living things) that inhabit a particular environment—often the body of a human or other animal. These microorganisms can be beneficial, harmful, or neutral to the animal they are living inside, and an animal’s microbiome can be an indicator of its health and lifestyle. For federally threatened and endangered species like the southern sea otter, microbiomes offer a promising new approach for monitoring disease, disturbance, and other threats.

Researchers collected samples from 158 wild, healthy sea otters living off the California coast, along with samples from captive sea otters at Monterey Bay Aquarium and captive otters from other species living at zoos. They then sequenced the DNA found in the samples to determine what kinds of bacteria were in the otter microbiomes and how the species found in the wild and captive otters compared to one another.

They identified more than 700 kinds of bacteria in the sea otter guts! But the proportion of bacterial DNA was surprisingly low compared to other mammals—the scientists think this may be related to sea otters’ super-fast metabolism, which helps them stay warm in cold ocean waters.

The new microbiome data for these healthy wild southern sea otters will serve as a baseline going forward, giving a wildlife managers a new tool to understand how sea otters respond to changing oceans.

Check out the open-access paper here.