Sea Slugs Traveling North as Ocean Temperature Rises

sea slugs

Pink sea slugs are on the move as climbing ocean water temperatures threaten their existence. Central and Northern California are beginning to be swarmed by rosy-colored sea creatures along the coast. Hopkins’ rose sea slugs, Okenia Rosacea, may be migrating northwards due to global warming, some scientists say.

Increasing worldwide temperatures have caused a huge flare-up of sea slugs present along the California coast. The Hopkins’ rose nudibranch, as they are called, are typically found off the coast of Southern California and further beyond. Normally, it is very rare that one would see a pink sea slug north of San Francisco; however, scientists are beginning to locate them in small coastal pools much farther north than that.

Scientists stated that very rare wind patterns have caused ocean temperatures off of the West Coast to rise. To date, they have not been able to explain the phenomenon.

These sea slugs are not the only strange guests to the area. Fisherman off the coast stated that they released a sea turtle back in early September. Sea turtles are only found off the western coast of Mexico and further south in the Galapagos Islands. Moreover, dolphins and humpback whales are being seen in Monterey Bay on a consistent basis.

Scientists in the area stated that the waters off of the coast of Southern California are five degrees warmer than normal averages for the first few months of the year. Logan Johnson, forecaster for the National Weather Service in Monterey, explained that currently the water in and around the area of Monterey Bay is in the high 50s, and the temperature continues to increase.

Normally, the vast increase in ocean temperatures would indicate that El Niño is approaching. This current trend in increasing warmth is caused by what is known as upwelling. Upwelling is caused when winds from the northwest carry water away from the surface, causing cold water to replace it. However, scientists have not located these northwesterly winds.

Evolutionary biology professor John Pearce, with the University of California – Santa Cruz, stated that still another phase of increasing temperatures is just beginning. According to Pearce’s report, scientists still do not know if the increase in temperatures is part of normal ocean oscillation or if it is greenhouse gases causing global warming that are interrupting the balance.

If currents were much colder, it would cause the range of sea slugs to decrease. Sea slugs feed on bryozoan, a rose-colored, moss-like plant that is found all along the West Coast as far up as Canada. Moreover, since the northward currents are bringing the sea slugs to the small tidal pools on the coast, the upwelling is not washing them into deeper waters off the coast.

Increasing ocean temperature is not the only thing that could potentially harm the sea slug’s way of life. Climate change could also cause ocean acidification from the breakdown of large colonies of sea coral, which would force many sea-dwelling animals out of the area. This would cause the sea slug’s main source of food to die out, thus leading to the suffering of the bright pink sea slugs. Until scientists solve the reason behind the increase in West Coast ocean temperatures, the sea slugs will have to travel further north in search of a new seasonal home.

By: Alex Lemieux


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Picture: Holly Clark – Flickr License

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