Edwards said this new discovery and description of a vertebrate, especially within the U.S., is very rare. The new species joins the 30 other species of Gambusia, which have a mostly subtropical distribution, including nine species that have been known to inhabit Texas waters.
|Above is a photo of the newest fish species, Gambusia clarkhubbsi. The top fish is a male and the fish below is a female.|
“I'm sure that somewhere, there might be another species to be found. Unfortunately you can't tell how rare this is until you find one,” Edwards said. “But, given that most aquatic environments have been sampled at least somewhat in the continental U.S., the chances of finding something new is quite remote. The new species of fish is a rare discovery.”
He said in the past he has made other discoveries, but this is the first discovery of a species that science did not know existed.
Gambusia clarkhubbsi, also known as the San Felipe Gambusia, was discovered and described by Edwards and Dr. Gary P. Garrett of the Texas Parks and Wildlife Department in Del Rio’s San Felipe Creek.
“The discovery of a new species in San Felipe Creek in Del Rio affirms that the fish fauna of this area is indeed unique,” Edwards said. “The University should take great pride that the research of its faculty is contemporary and significant.”
Most recently the international journal of Copeia, the official publication of the American Society of Ichthyologists and Herpetologists, described the new vertebrate species in the current issue.
Edwards said since the discovery in 1997, it took some time before he and Garrett determined it was an entirely new species of fish. The new fish belongs to a group called mosquito fish – named because they consume vast quantities of mosquito larvae and are instrumental in the control of mosquito-borne disease vectors. They have been introduced worldwide as mosquito control agents, Edwards said.
“The first collection was in 1997, but it took a while before we had enough specimens, and had compared these to all other known species of mosquito fish to make the determination that this was entirely new,” he said.
The fish, a member of the Gambusia nobilis species group, are adapted to specific spring environments, mostly in central to west Texas and parts of New Mexico.
“Most of the major springs in Texas have a unique member of this species group so it was always a mystery why San Felipe Springs – the third largest springs in Texas – did not have a member of this group. We now know that it does,” he said.
The finding was a complete surprise to both fish biologists, Edwards admits they stumbled on to Gambusia clarkhubbsi by accident. He said they were both at the San Felipe Creek to study the abundance of several imperiled fishes in the area including the Devils River minnow (Dionda diaboli); one of the U.S. endangered species.
Edwards said the species was named Gambusia clarkhubbsi in honor of Dr. Clark Hubbs, an emeritus professor at The University of Texas at Austin, who has had a long history of research on the ecology and taxonomy of this group of fishes.
“He has spent a lifetime in the pursuit of the conservation of rare fishes, especially in the state of Texas,” Edwards said. “He also introduced Dr. Garrett and I to the scientific study of fishes when we were his graduate students at The University of Texas at Austin and later as colleagues of his in our joint studies of Texas fishes.”
Both biologists believe two events played an important role in the discovery of the species. Edwards said the species was once restricted to limited habitats until the City of Del Rio and its local country club changed their land use operations around the San Felipe headsprings and creek in 1997.
Also, a major flood in 1998 scoured the stream, which led to the removal of impediments and years of accumulated sediments – which Edwards said might have held toxic remnants of fertilizers, pesticides and herbicides used in years past.
“We think that the species was present in San Felipe Creek in very low numbers until certain land-use changes occurred within the city limits to make the creek more ‘environmentally-friendly’ to the aquatic inhabitants,” he said. “We believe that this flood and the forward-thinking actions of the City of Del Rio has been responsible for the increased abundance of the new species and accounts for its recent discovery.”
Edwards said he is currently conducting additional research on the ecology and life history of the new species in an effort to determine its requirements to be able to survive in its environment.
Ultimately, both biologists believe fish conservation is important to the quality of life and the environment, therefore making it their mission to educate the public about fishes and their significance in the world.
“Because fish are so intimately tied to water, they serve as excellent indicators of the quality of the environment. They can be compared to the ‘canary in a coal mine.’ When the canary began to die, the miner knew that something was wrong,” he said. “Similarly, by observing the health of the fish communities inhabiting a body of water, we can make judgments about the quality of the environment for ourselves. If the fish are in trouble, then it won't be long before we are too.”