Tide pools along the coast of central and northern California are filling up with inch-long, pink Hopkins' rose nudibranch, a sea slug whose vivid coloring gives it a kind of punk rock appeal.

Colder currents likely are limiting the southern sea slug's range because their prey lives along the Pacific Coast up to British Columbia, believe a team of researchers from UC Santa Cruz's Institute of Marine Sciences, UC Santa Barbara's Marine Science Institute, the California Academy of Sciences and University of Zadar, Croatia believe.

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The Hopkins' rose nudibranch gets its pink pigmentation by eating a rose-colored encrusting bryozoan, which is a moss-like species.

Researchers added that warmer ocean temperatures triggered a population explosion of the Hopkins' rose nudibranch beyond its normal Southern California range.

The brilliant pink sea slug is uncommon north of San Luis Obispo and even rarer north of San Francisco. Scientists in Santa Cruz, San Francisco and Bodega Bay have spotted the tiny puffs concentrating in tide pools as far north as Humboldt County.

The sea slugs haven't been seen in such numbers in the colder parts of California since 1998.

Now, northward and onshore currents are carrying the slug's larvae to tide pools and they aren't being washed away by upwelling.

"The nudibranch can just crawl short distances and don't live very long," said Jeff Goddard, a scientist at UC Santa Barbara's Marine Science Institute, so they're useful in monitoring quick changes in ocean conditions.

"There are some detrimental impacts to the ecosystem," Goddard said. "Higher temperature often means the water is less productive."

TagsOcean, sea slug, pink Hopkins’ rose nudibranch, rose nudibranch, warm ocean