Scientists say a tiny endangered fish found in lagoons and streams along the California coast belongs to two separate species.
The tidewater goby, a 2-inch translucent fish, survives in relatively isolated populations from Del Norte County down to San Diego. The fish spend most of their lives in the same puddles, rarely traveling far from where they spawned.
The southernmost groups, cut off from the north by the rocky headlands of Palos Verdes, show the distinctive genetic and physical characteristics of a new species, which is described by scientists from the Natural History Museum of Los Angeles County and UCLA in a paper published Wednesday in PLOS One.
The southern tidewater goby lives in only a few spots at Camp Pendleton, making the designation as its own species a critical one for its conservation, said David Jacobs, a biologist and geologist at UCLA who helped identify the species with the museum's Camm Swift.
"This [new] species is very, very highly endangered," Jacobs said. "It can go away in the blink of an eye."
The tidewater goby's survival is linked to the existence of lagoons, which are threatened by coastal development and the ongoing drought, Jacobs said.
"It's not a coincidence these things are now only on Pendleton," Jacobs said.
During the summer months, ocean-bound streams dry up and form lagoons and ponds along the coast. It's in these puddles that male gobies dig burrows in the sand, where they'll protect their eggs. Females put on colorful display rituals near the entrance of the burrows to compete for males.
By the time goby larvae grow, winter rains may open the ponds and lagoons to the sea. This sometimes allows the fish to find new streams along the coast.
But if the gobies do travel, it's only for short distances — and if nothing blocks their way.
About a million years ago, however, the Palos Verdes cliffs rose from the sea and divided the tidewater gobies' potential range in two. Since then, the groups have been left to evolve in isolation from one other.
The fish that live north of Los Angeles County keep the original species name, Eucyclogobius newberryi.
The southern tidewater goby (Eucyclogobius kristinae) has fewer rays on their fins and more "neuromasts" — organs that allow fish to sense movement in the water. The researchers noticed the differences by examining 145 preserved specimens from the natural history museum's collection.
The new species has been found in nine lagoons in northern San Diego County over the past 30 years. As of last winter, scientists could find the fish only at Camp Pendleton.
The southern tidewater goby's true historic range is difficult to measure, Jacobs said.
Tidewater gobies were first described as a species in the San Francisco Bay Area in 1856. By the time the fish were collected south of Los Angeles in 1939, the coastline had been reshaped by oil production. Swift and Jacobs infer the southern tidewater goby's historic range stretches as far north as San Pedro.
Swift, Jacobs and colleagues first suggested the northern and southern fishes belonged to two distinct species in a 2009 study that found significant genetic differences between the groups.
E. kristinae is named after the late Kristina Louie, who co-authored the genetic study of the southern tidewater goby as one of Jacobs' doctoral students. Louie died in 2004 shortly after earning her PhD.
Last winter, Jacobs' lab, along with the U.S. Fish and Wildlife Service, Camp Pendleton and the Santa Monica Pier and Birch aquariums, captured and temporarily housed gobies in case flooding from El Niño storms washed away their habitat.
Jacobs said his team is looking to reintroduce the southern tidewater goby in additional locations around their historic range.
"With a little bit of effort and thought, the people of Orange and San Diego counties can coexist with this thing with very little effort," Jacobs said.
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