Otters feel the burn from wildfires

In the summer and fall of 2008, two major wildfires burned more than 70,000 hectares of California’s Big Sur area. Now researchers have found that sea otters may have suffered as a result.

Scientists have done plenty of studies on how wildfires affect land animals. Habitat, diet, and reproduction rates can all be thrown out of whack after the smoke clears. But do these fires affect nearby ocean critters too? That’s an important question to answer because researchers predict that wildfires in North America will get bigger and fiercer in upcoming decades. For instance, marine animals might be exposed to higher levels of carcinogenic chemicals called polycyclic aromatic hydrocarbons (PAHs).

Two fires in Big Sur gave the study authors a chance to test this hypothesis. The Basin wildfire occurred in June and July 2008, followed by the Chalk wildfire in September and October that year. The researchers collected blood samples from 39 otters in Big Sur in November 2008 and 2009, then analyzed the animals’ genetic material. They also examined blood samples from 42 normal sea otters, some in captivity and some living off the Alaskan coast.

When the researchers compared gene expression patterns between the Big Sur otters surveyed a month and a year after the fires, they found some differences. The recently-exposed animals showed signs of detoxifying PAHs and reduced immune system function, which would make them more vulnerable to diseases. Similar differences were seen between the 2008 Big Sur otters and the normal captive and Alaskan animals.

After the fires, ash and charcoal were probably deposited off the coast, the authors say. It’s reassuring that the otters sampled in 2009 appeared mostly back to normal. But researchers will have to do more work to determine whether wildfires have any lingering effects. Roberta Kwok | 14 August 2014

Source: Bowen, L. et al. 2014. Effects of wildfire on sea otter (Enhydra lutris) gene transcript profiles. Marine Mammal Science doi: 10.1111/mms.12151.

Image © worldswildlifewonders | Shutterstock

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