Are Putrid Lakes "the Color of Antifreeze w/Chunks of Broccoli Floating" Killing Sea Otters?

By Andrew Moseman | September 24, 2010 2:17 pm

Sea_otterCalifornia sea otters, furry frolickers of the saltwater seas, are in trouble. And the root cause is… a freshwater toxin? That’s the surprising truth, according to a study in the journal PLoS One led by Melissa Miller, a state wildlife veterinarian.

For the last several years, the otters on California’s coast have been dying in droves, and their population diminishing. No one could quite put a finger on why. Disease and starvation floated as explanations, and sharks seem to be devouring more sea otters lately. But none of these were the root cause, Miller finally found.

Instead, she says, the culprit is a blue-green algae called Microcystis. This type of simple bacteria loves stagnant, nutrient-rich fresh water, and it’s been showing up more and more lately in coastal California locales like Pinto Lake, near Monterey Bay.

“The best way to describe it? The lake turns the color of automobile antifreeze with chunks of broccoli floating in it,” said Robert Ketley, water quality manager for the nearby city of Watsonville. “It’s that grotesque. When the scum dries, it has a turquoise color to it.” [Los Angeles Times]

Microcystis thrives in freshwater, but the cycle of water carries it out to sea.

Eventually the fresh water flows into the ocean, carrying the algae with it. However, the toxin does not break down right away as it reaches the salt water. It can last well over three weeks without any serious degradation. [Reuters]

During that time, the thinking goes, the toxin enters shellfish that nourish themselves by filtering the water. Sea otters love to eat shellfish, and chowing down on contaminated ones builds up the toxic concentration. To test this idea one step further, Miller bought pounds of oysters and mussels and tested exposing them to Pinto Lake water. The result? The shellfish showed toxic concentrations of more than 100 times that of the surrounding water.

Microcystis has been around for billions of years, so why the sudden resurgence of its super-blooms? One oft-mentioned factor is nutrient-rich runoff from agriculture. But the study teams says climate may play a role as well.

Raphael Kudela, a professor of ocean sciences at UC Santa Cruz and co-author of the study, cautioned that blue-green algae may be spreading, at least in part, because of climate change. Their study did not look at the issue directly, but Kudela in an interview cited other research that connects warming with the algae. “Climate change could be a factor,” Kudela said. “These algae like warm, high-nutrient waters.” [The New York Times]

Related Content:
DISCOVER: Ocean Acidification: A Global Case of Osteoporosis
DISCOVER: Curb Your Cat, Save a Sea Otter
80beats: Out-of-State Mates Bring Florida Panthers Back from the Brink

Image: Wikimedia Commons

CATEGORIZED UNDER: Environment, Living World
  • Rhacodactylus

    OH NO!!! I was fine with blowing off environmental concerns before, but now that we are killing something cute, we MUST take action =)

  • Jockaira

    So nice that you are finally cuddling up to the furry side of your nature…

  • Zachary

    What, emotional responses are a good way to get people involved in collective action problems!? Yeah Rhacodactylus, enjoy your arrogant cynicism and have fun patting yourself on the back for being above it all.

  • Dante The Canadian

    Okay so once again Global Warming is BLAMED partially for this issue. Global Warming is becoming the crying call for everythnig bad in our environment. This is a dangerous road to drive on in my opinion. Many other factors are causing the deaths and degradations of our environment. The use of herbicides and pesticides, the over use of fertilizer in farmers fields, the over use of water dwindling natural fresh water run off into the lakes and rivers that lead to the ocean (This is an issue because the more fertilizer that is run off into the lakes and rivers, the less water there is to absorb it causing an issue of ‘concentration’ in the water column) are bigger contributors to this pollution issue.


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