April 30, 2018

Rare Species Sighted in California, New Species Added to RCCA Survey Protocol

Crowned urchin
Point Lobos State Marine Reserve

By Jan Freiwald, Selena McMillan and Dan Abbott

Reef Check California’s (RCCA) 2018 survey season is just about to start, but we have already made some interesting observations during recent dives. RCCA staff have observed several species outside of their normal range, suggesting that certain species are expanding their historically southerly ranges northward. These sightings are likely the result of the recent warm water and El Niño events that have occurred in recent years. In 2016, RCCA reported the first sighting of a crowned sea urchin (Centrostephanus coronatus) in central California (Freiwald et al. 2016). This species of sea urchin was previously only found as far north as the Northern Channel Islands and has a historical distribution ranging from the Galapagos Islands in the south to Southern California in the north. In March of this year, during a dive in Point Lobos State Marine Reserve, our Southern California Regional Manager, Dr. Selena McMillan, documented a crowned urchin for the second time in central California. On a reef in Whalers Cove, a common dive destination, she observed a crowned urchin among purple and red sea urchins, which are typically found in the region.

This is not the only observation of typically southern species on the central coast in recent months. During a recent training dive for students from California State University Monterey Bay, Dan Abbott, RCCA’s Central California Program Manager, and others saw a female rock wrasse (Halichoeres semicinctus) at the breakwater in Monterey. This fish species is not commonly found north of Point Conception, which marks the northern range boundary of many species found in southern California. While southern species have been observed in central California from time to time, in recent years these observations seem to have become much more common in the Monterey/Carmel Bay region.

Finescale triggerfish. Breakwater, Monterey. Photo: Patrick Webster

During a recent dive, Kate Vylet, RCCA’s Climate Change Monitoring Coordinator, and Dan Abbott saw an even less common fish species in central California. They found a Finescale Triggerfish (Balistes polylepis) sleeping in the sand near a reef along the Monterey Peninsula. Though triggerfish are primarily found on coral reefs, the finescale triggerfish has a wide geographic range, including the entire North American west coast, but it is rarely seen in central California. This fish has become more common in southern California recently, where similar increases in its abundance have been observed after previous El Niño events. This is why RCCA has added this species to its species list and is teaching volunteers now to look for it anywhere during their survey dives.

Another species that has become increasingly common in southern California is the Largemouth Blenny (Labrisomus xanti). This species’ historical range expanded northward into central Baja California, Mexico and was first reported in California in 2015, near La Jolla (Love et al. 2016). Now they are fairly common at Santa Catalina Island and are being seen throughout southern California. Evidence of their reproduction has also been observed in larval collections off the coast of Palos Verdes (Milton Love, personal communication). RCCA has added Largemouth Blennies to its species list and is now documenting their densities and potential range expansion in southern California and statewide should they start showing up even further north.

RCCA has also added a new kelp species to its surveys this year. We have observed changes in the composition of kelp in many of our southern sites in recent years, noticeably the emergence of feather boa kelp (Egresia mensiesii) in place of or among giant kelp (Macrocystis pyrifera). The feather boa kelp is native but is usually found at very shallow depths and in the intertidal. With the warm water events that have occurred, we have observed this species’ expansion into deeper, subtidal waters. We will now be counting individuals and stipes of individuals to estimate densities of this alga within the kelp forests that we survey.

Female rock wrasse
Casino Point, Catalina Island
Feather boa kelp
Pt. Loma, San Diego

Largemouth blenny
Twin Rocks, Catalina Island

Photos: Selena McMillan