Large patches of bright orange/red water – that “stunk really bad” – were spotted (and sniffed) near Burien’s shores this week, with these photos by Deana Anderson taken at Three Tree Point’s north beach:

And no, it’s not a “red tide,” which can be toxic for mammals – it’s a bloom of “Noctiluca,” which is marine algae or plankton that happens seasonally in Puget Sound.

Algae are present all year, according the the Washington State Department of Ecology, but sunshine, nutrients, and warm temperatures often create large seasonal blooms like this week’s.

But don’t worry – experts say that Noctiluca blooms are nontoxic and usually appear as a rusty reddish color like tomato soup, and are common in Puget Sound.

Ecology says that Noctiluca is a solitary microorganism belonging to the dinoflagellates group, known for its predilection for consuming smaller phytoplankton and planktonic larvae, which are crucial components of a thriving marine food chain.

Notably, Noctiluca’s unpalatable nature stems from its remarkably high concentration of ammonia, rendering it a stinky, unappetizing target for other organisms within the food chain.

Some research indicates that this ammonia-laden organism exerts a detrimental effect on juvenile fish residing in the Salish Sea.

According to the agency, Noctiluca’s presence in Puget Sound can be traced back to natural occurrences, with recorded observations of its blooms dating as far back as the 1940s. However, Ecology expressed greater concern over the escalating intensity, altered timing, and expanded distribution of these blooms, attributable to the over-enrichment of nutrients caused by human activities. This revelation raises pressing questions about the potential consequences of human-induced changes to the delicate ecological balance within Puget Sound.

Ecology has more info on Notiluca in this PDF poster.


Below are some videos courtesy KING5 about the bloom, as seen in West Seattle:

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2 replies on “PHOTOS: Here’s why the waters off Burien were reddish/orange and ‘stunk really bad’ this week”

  1. There is a company down in SW Washington that filters salt water to make a fertilizer that has nutrients that are hard to find any where else. Maybe we need to start filtering our salt water in Puget Sound and make fertilizer for our forests and home gardens?

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