Posts Tagged sea slug

Feb 2 2015

Pink sea slugs swarming northwards as ocean temperatures rise

pink-sea-slugThe bright pink sea slugs are typically found in Southern California, but have been found moving farther and farther north as ocean temperatures increase, possible due to global warming.

Central and Northern California are beginning to take on a pink hue as Hopkins’ rose sea slugs take over — something that scientists say may be due to global warming.

The increasing global temperatures have caused an explosion in the population of the Hopkins’ rose nudibranch beyond Southern California, where it is typically found. Usually, it is extremely uncommon north of San Francisco, but scientists are spotting them in tide pools far north of that, according to a Santa Cruz Sentinel report.

Rare wind patterns that scientists have yet to explain have caused temperatures in West Coast oceans to rise, which has lured the sea slug far best its typical range.

And it’s not the only unusual visitor to the area, with fisherman in San Francisco capturing a sea turtle back in September that in the past would have only been found off the coast of Mexico or the Galapagos far to the south. Meanwhile, humpback whales and dolphins are being spotted on a regular basis in the Monterey Bay, according to the report.

Scientists say the waters off the coast are about 5 degrees higher than they normally are for most of 2014, and it has just been increasing in warmth, according to Logan Johnson, a National Weather Service forecaster in Monterey, who was quoted in the report.

Currently, waters in the Monterey Bay are running in the high 50s, and it’s staying there.

Typically, such temperatures would suggest that El Nino is on its way. The current warming is being created by what is known as upwelling, which is when Northwesterly winds blow away water at the surface, causing colder waters farther down to replace it — but scientists haven’t spotted those winds.

John Pearse, an ecology and evolutionary biology professor at the University of California Santa Cruz, said another warm phase is beginning, although scientists have no way of know if this is part of normal oscillation or if it’s global warming, according to the report.

Colder currents could be causing the sea slug’s range to shrink because their prey — rose-colored encrusting bryozoan, a moss-like life form — can be found up and down the Pacific Coast as far north as British Columbia. Now that northward currents are carrying the species larvae to tide pools, upwelling isn’t washing them away.

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