The Hopkins' rose nudibranch (Okenia rosacea) is moving northward as ocean temperaturess warm. Photo courtesy of UCSC's Institute of Marine Sciences
SANTA CRUZ, Calif., Feb. 2 (UPI) -- Species of all kinds have been slowly shifting their habitat as climate change affects temperatures on the ground and in the sea. On the Pacific coast, that migration is a bit more colorful.
As ocean temperatures have warmed over the last two decades, a bright pink species of sea slug has been inching northward, following its preferred thermostat settings up the coast of California. They are one of many marine animals on the move in reaction to a changing climate.
The Hopkins' rose nudibranch (Okenia rosacea), a colorful, inch-long sea slug, can be found up and down the West Coast, from Baja to the Puget Sound. The slug is most common in southern California, where it can routinely be found meandering about tidal pools. Their presence is sporadic in central California, and finding one north of San Francisco is rare.
But in a study using decades of nudibranch data, researchers at the University of California, Santa Cruz say the pink slugs are appearing in increasing densities in northern climes.
"We haven't seen anything like it in years. These nudibranchs are mainly southern species, and they have been all but absent for more than a decade," John Pearse, professor emeritus of ecology and evolutionary biology at UC Santa Cruz, explained in a press release.
Sea slugs like the Hopkins' rose nudibranch have moved northward before, but only during El Nino events -- the irregular climatic phenomenon during which warm bands of Pacific water stretch northward from the tropics.
An El Nino event hasn't been observed in recent years, but scientists now wonder if the sea slugs recent migration is a sign of an impending climatic shift.
