Explained: Strangely Colored Tides of Oregon / Washington Coast in Blue, Pink, Brown or Purple

Published 04/08/21 at 3:35 AM PDT
By Oregon Coast Beach Connection staff

(Oregon Coast) – Ever walk along the beaches of either the Oregon coast or Washington coast and discover the waves or the sea foam are a weird color? Maybe pink? Maybe a strange shade of purple? Or maybe brown and sludgy?

It’s all – yes all of it – a natural occurrence. And no it is not pollution. Though admittedly even for marine science some of it is definitely on the strange side. The pinks or blues come from the sheer numbers of some marine creatures. Not from them “leaking” some kind of liquid out of them, but simply that they’re so small and there are so many that they taint the water around them.

Brown waves – well that’s another oddball thing, and it usually just happens up around Seaside, Warrenton and southern Washington coast areas like the Ilwaco or Long Beach. This is a positive sign and it affects a lot of exceptionally cool aspects of those areas.

Purple waves created quite a stir back in 2015. It was the first time any experts had noticed this, brought to light because an Oregon Coast Beach Connection (OCBC) reader sent in photos to the publication. As OCBC passed around the images from Neskowin to scientists at the Hatfield Marine Science Center, Oregon Department of Fish and Wildlife and others, everyone was puzzled. Photos were sent along to universities and no one could identify it.

Experts at the Hatfield that had been there for 30 years had not seen anything like it.

Finally, water samples were taken from Oregon by Washington Department of Fish and Wildlife and then it was identified first as a kind of salp, but scientists later changed the designation as a doliolida, a pelagic tunicate. That means it’s a tiny animal somewhat related to salps and those weird pyrosomes, and they too live out at sea. It’s actually a species called Dolioletta gegenbauri and they were in their early stages of life which made them even smaller.

Adult size is maybe about a millimeter.

According to Tiffany Boothe of Seaside Aquarium:

“While most doliolida prefer warmer waters gegenbauri is cold water tolerant,” she said. “Concentrated swarms like those that we saw are capable of clearing out the phytoplankton where they are living in a single day.”

Boothe said really tiny Velella velella also can turn waves blue, but it’s more subtle.

Pink waves is a bit up for debate. This too happens very rarely, and it’s largely due to an enormous flood of skin-breathing sea cucumbers.

OCBC documented it once in Manzanita back in 2010. There, the foam and the thin layer of waves rolling onto the beach were found to have a slight pink color or sometimes just in blobs, which was exaggerated by the sunset at the moment this photo was taken.

They’re called burrowing sea cucumber (Leptosynapta clarki) and they largely stay out of sight, burrowing into the sand around the tideline. If you see a whole one, they look like part of an inner organ from some creature. In incredibly great numbers they can cause a pink hue to parts of the waves.

Brown surf on the north Oregon coast or southern Oregon coast are caused by something even tinier: diatoms, a form of phytoplankton. It appears in the form of brown goo or large blobs of the stuff, sometimes even big, dark globs that look like oil. The sight sometimes causes visitors to run to local stores and tourism agencies to inquire about whether this is pollution or an oil spill.

In fact it’s a sign of a healthy ocean. In these areas that flank the Columbia River, there are so many nutrients coming in from the Columbia and other sources that diatom blooms are absolutely insane sometimes.

Those same nutrients also help create such an abundance of whole sand dollars in Gearhart and northern Seaside around the Necanicum. MORE PHOTOS BELOW

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