That photo texted from The Arroyos in southwesternmost West Seattle is first word we got today of that alarming-looking but relatively common phenomenon. It’s not “red tide” but rather a bloom of microorganisms called Noctiluca – explained here by the state Ecology Department, which says that “sunshine, nutrients, and warm temperatures contribute to large seasonal blooms.” Experts say it’s not toxic but it is a sign of environmental imbalance, as noted here.
Is this Noctiluca Scintillans?If so, how likely is it to be bioluminescent?
This is N. scintillans, and with a big bloom like this there’s a decent chance the water will sparkle at night if you agitate it with a stick or go swimming in it. We don’t really get the brightly lit waves like they do in CA, but you can definitely have glowing beaches, and glittery waters this time of year.I also just want to add that a Noctiluca bloom can be a sign of an overabundance of nutrients, but isn’t always one. Right now we have the most sunlight of the whole year and strong tidal mixing has pulled nutrients up from the bottom, but the wind has been calm enough that distinct layers of water can form and plankton aren’t getting dragged out of the sunlight. This is the time of year when the conditions are ideal for dinoflagellates (like Noctiluca) and other types of plant plankton (like diatoms) so they are going to turn up in large aggregations. The author of the article referenced even mentions that it’s the huge scale of the blooms that researchers were seeing in 2018 that was disconcerting, not that they were there generally. Arroyos to Lincoln Park is a decent stretch of beach, but not anywhere near what we see when these blooms are really intense.For anyone with kids, or who just likes looking at cool organisms, Noctiluca is a great species to look at under a microscope or with a high power (40x) field lens. You can see their sunlight gather cells, and watch them waving their little flagella around to eat. Grab a cupful and check em out!
This works well:
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This bloom is actually getting big and is off Vashon and Bainbridge as well
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