Weird, Brown Waves Return to N. Oregon Coast - It's a Good Thing and What Else It Means

Published 11/16/22 at 2:39 AM
By Oregon Coast Beach Connection staff

(Seaside, Oregon) – Those funky, sometimes disturbing brown waves are back on the north Oregon coast, at least in the Seaside area if not farther north into the Washington coast as well. (Above: brown surf bubbles in Seaside in recent days. Courtesy Seaside Aquarium / Tiffany Boothe)

To many it looks like oil or sludge in the water. Other times it can look a bit like chocolate, although not an appetizing kind. It's a good thing, however; a sign of a healthy ocean.

“Very large diatom blooms happening in Seaside,” said Tiffany Boothe of Seaside Aquarium. “All of our local filter feeders are feasting.”

All that murky brown stuff is simply the product of so many diatoms that they cause a thickening of the water and create their own color.

Seaside in recent days, photo Seaside Aquarium

Diatoms are a form of phytoplankton, the single-celled plants that are found in both fresh water and salt water.

“They are one of the most important food sources in the ocean,” Boothe said. “In the winter, spring, and early summer, diatoms rapidly multiply in the surf zone. Diatoms absorb large amounts of nitrates and phosphates that are delivered to the ocean by coastal rivers, contributing to their population explosion. Everything in the ocean feed on diatoms and other plankton, either directly or indirectly. Even great baleen whales, like the gray whale, filter plankton and diatoms as part of their diet.”

It's something that's quite unique to the north Oregon coast and south Washington coast: you won't necessarily find it in places like the beaches of Newport, Oceanside, or Coos Bay. While it can happen in other spots on a rare basis, usually if you see brown waves in these areas it's mud stirred into the breakers by a lot of storm action. That mud comes from some river nearby.

Diatoms under a microscope, Seaside Aquarium

Keith Chandler, manager of the Seaside Aquarium, told Oregon Coast Beach Connection it has alarmed people in the past, but for years now the aquarium’s placards and signs explaining the phenomenon have usually put fears about pollution to rest.

The stuff feels pretty grimy, and it will stain your clothes more than regular surf. Sometimes, these gobs of diatoms look like big stains on the beach as well.

“It’s not really so much of a stain as it is a lot of the stuff accumulates on the beaches,” Chandler said. “The stuff, like the brown bubbles, feels a little oily, but that doesn’t mean it is oil. It just comes from a lot of it piling on the beaches. The tide will come and clean it out. Just like a ketchup stain – it comes right out.”

Diatoms are also the basic foundation for bubbles in the surf anywhere on the Oregon and Washington coast. That sea foam you find, sometimes in huge, snow-like clumps, is essentially made up of one kind of phytoplankton or another.

All these diatoms feed some extra large amounts of other lifeforms in the surf zone, such as sand dollars and baitfish (the latter will sometimes bring orcas or humpbacks around). See the story Intriguing Connection to Clams, Diatoms, Brown Waves and Washington / Oregon Coast

Then there's another very cool aspect of these massive blooms which isn't talked about much. If there's a lot of these diatoms, then it could be a sign there's a lot of other kinds of phytoplankton – like dinoflagellates. Those are the bioluminescent ones, the creatures that cause glowing sand or glowing waves.

That's right: this is a good time to check darker beaches in the area for that glowing phenomenon. See Bioluminescent Phytoplankton: What Makes Glowing Sand On Oregon Coast, Washington

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Sludgy waves, photo Oregon Coast Beach Connection

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Andre' GW Hagestedt is editor, owner and primary photographer / videographer of Oregon Coast Beach Connection, an online publication that sees over 1 million pageviews per month. He is also author of several books about the coast.

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