Cause Identified for Purple Tides Noted by CoastWatchers

Photo of purple water.

Mysterious purple patches are being observed along the coast. The answer to the summer's trick CoastWatch question, "What is causing the purple water?" turned out to be "salps." Numerous reports came in over a period of weeks concerning “purple water” or “a gelatinous purple mass” in the water.

It took a while to determine the cause, and several suspects were suggested. Finally, though, Caren Braby, manager of marine resources for the Oregon Department of Fish and Wildlife, confirmed that “My staff have been communicating with WDFW (Washington Department of Fish and Wildlife) and taken samples at Clatsop Beach. They are a huge bloom of juvenile salps - a gelatinous VERTEBRATE, more closely related to fish than to jellies. This may be an unusual sight for us because of two or more possible (hypothetical) reasons: 1) they may be blooming significantly this year due to unusual ocean conditions, or 2) they are usually out there but this year they are onshore due to the suppressed upwelling (the "Blob") pressed up alongshore."

For more images of the “purple tide,” go to the Oregon Shores Facebook page, or to CoastWatch mile 253.

Marine ecologist Cynthia Trowbridge will discuss salps, along with other unusual shoreline sightings this year, as part of the Oregon Shores annual meeting, Nov. 7 in Lincoln City (see article elsewhere on this page for information about the event).

CoastWatcher Range Bayer has supplied links that may be of related interest: