“Killer” Sea Slug on the Loose in Marin


Jeffrey Goddard
Marine Science Institute
UC Santa Barbara
E.: jeff.goddard@lifesci.ucsb.edu
T.: (805) 688-7041

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March 7, 2011

Sea slugs feeding. Photo: J. Goddard/UCSB

Sea slugs feeding. Photo: J. Goddard/UCSB

March 7, 2011

Contact: Christina S. Johnson, csjohnson@ucsd.edu, 858-822-5334

A dangerous nudibranch is taking over tide pools in Marin County, a biologist reports.

The species, Phidiana hiltoni, attacks, dismembers and “slurps up,” other sea slugs, says marine biologist Jeff Goddard of UC Santa Barbara.

Goddard, whose work is being funded by the Ocean Protection Council, blames the large, predatory sea slug for declines in other nudibranch species at the large, shale-bottomed Duxbury Reef in Marin County.

P. hiltoni feeds on a hydroid. Photo: B. Green

More notably, the sea slug’s range expansion appears to be an example of how basin-scale climate change can affect local ecosystems.

Up until recently, the "killer" nudibranch was basically considered a Southern and Central California species, with the heart of its range in places like Laguna Beach in Orange County.

It was documented north of the Monterey Peninsula for the first time in late 1977. Since, the large, predatory mollusk has been moving north, either displacing or consuming competitors.

At least two other shallow-water marine invertebrates have spread northward since the late 70s – the Kellet’s whelk (Kelletia kelletii) and acorn barnacle (Tetraclita rubescens) – a pattern attributed to climate change.

To learn more about the effects of climate change on populations of these colorful mollusks, visit: http://www.csgc.ucsd.edu/BOOKSTORE/Resources/PP2011/R-OPCENV-08-Goddard.pdf