Monday, January 9, 2017

Extinction and Saving Species

"Living wild species are like a library of books still unread. Our heedless destruction of them is akin to burning the library without ever having read the books" -John Dingell, Former Congressman and Author of the Endangered Species Act

The Tecopa Pupfish, Cyprinodon nevadensis calidae, the first organism which was removed from the Endangered Species Act due to extinction. The extinction of this fish was declared to be entirely preventable by Assistant Secretary of the Interior Robert L. Herbst. Photo by U.S. Fish and Wildlife Service.

Deserts are difficult places to live for plants and animals. High temperatures, lack of food and water, and extreme variability combine to push organisms towards the edge of their existence. Too often human disturbances and modifications in desert systems have provided a final push into extinction for many desert organisms. Biologists are aware that the idea of a species has a real temporal element as well, in other words species as we know them now are temporary. Their genetic and morphological characteristics can and do change as time goes on. Some species go extinct, some species get "re-absorbed" into their sister species through hybridization, and some survive and change due to natural selection and genetic drift. Some biologists have proposed the "ephemeral speciation model", likening species to a desert stream, in other words species are temporary and subject to change. Extinction is not a new phenomenon by any means.

What is worrying today is that humans can so quickly end the existence of so many species before we have a chance to understand them. Extinctions are happening faster today than they have in the past, this is certain. 

But what we must not forget in these times is that humans, in many cases just a single individuals or group of individuals, can save an entire lineage from almost certain demise. The last few months have been troubling for me as a biologist, a conservationist, and a person who cares about desert species and landscapes threatened by a changing climate. Perhaps you have had similar feelings given that some world leaders seem to revel in ignorance when we know that human lives and entire species are at stake. 

It is important to learn from our failures, but also to celebrate our successes in conservation. I aim to do so here by focusing on a few stories from the deserts I love so much. One story that ends in extinction, one that ends in success but uncertainty, and one that ends in recovery and hope. 

The Tecopa Pupfish: Water for soaking, but not for fish
The Tecopa Pupfish was a subspecies of pupfish native to a few spring outflows and hot spring systems outside of Tecopa, California. In the 1960s and 1970s bath houses were constructed for tourists and the spring system of the Tecopa Pupfish was heavily modified and altered. The stream course was diverted and pupfish habitats became much hotter. Modifications also allowed other pupfish to swim into the Tecopa Spring system and hybridize with the endangered Tecopa Pupfish. The introgression between the Tecopa Pupfish and other closely related species coupled with habitat modification eventually led to the Tecopa Pupfish having the distinction of being the first endangered species to be removed from the Endangered Species Act due to its extinction. More careful planning and mitigation efforts during construction of the bath houses could have entirely prevented the extinction of the Tecopa Pupfish according to the Assistant Secretary of the Interior at the time. 

The Pahrump Poolfish, Empetrichthys latos, is extinct in the wild but was saved from total extinction due to the efforts of University of Nevada, Las Vegas Biologist Dr. James Deacon. Photo by U.S. Fish and Wildlife Service.

The Pahrump Poolfish: A species in a bucket
The Pahrump Poolfish was previously found only in Manse Spring outside of Pahrump, Nevada in the Mojave Desert. The species is the only living representative of its genus and faced almost certain extinction several times during the 1960s and 1970s. Vegetation at Manse Spring was removed to construct a swimming hole for locals in addition to goldfish being introduced in the spring. The lack of cover in Manse Spring and the competition with newly introduced goldfish caused the population to crash to less than 50 individuals on two separate occasions. Finally in 1975 it seemed like the prospects for the Poolfish were nonexistent. Ground water pumping nearby led to the eventual drying of Manse Spring and would have led to the extinction of the Pahrump Poolfish if not for the efforts of Nevada biologist James Deacon. Aware of the impending demise of Manse Spring and the extinction of its poolfish, the last member of its genus, James Deacon removed every living individual poolfish from Manse Spring in a 5 gallon bucket. 

I sometimes reflect on how Dr. Deacon must have felt that day, removing an entire species from the wild, unsure if they would ever return to their native spring or if they would stave off extinction at all. I know that if I had been there, it would have been unlikely that I could have held back tears. 

The Pahrump Poolfish still exists due to the efforts of Dr. Deacon and others, but it has not yet been returned to Manse Spring. It is unclear whether suitable habitat will ever enable their reintroduction into their former home.
The Relict Leopard Frog, Lithobates onca, once thought extinct, now thriving in several locations in Arizona and Nevada. Photo by Tom Brennan


The Relict Leopard Frog: From "extinct" to "not warranted for listing as endangered"
The Relict Leopard Frog, Lithobates onca, was thought to be extinct for some time, though there were rumors that some frogs still existed in their former habitat. Biologists in the 1990s discovered frogs at former sites where Relict Leopard Frogs were known to exist in Nevada, and studies confirmed that these frogs were indeed the Relict Leopard Frogs, long thought extinct. Since the discovery multiple partners and agencies got to work and within a fairly short period of time conservation plans were in place and biologists got to work reintroducing Relict Leopard Frogs to their former habitat and collecting eggs for use in translocation experiments in an effort to save the species. 

Despite the fact that it was once thought extinct, many new populations of Relict Leopard Frog are apparently breeding and thriving. Recovery efforts have been so successful that recently the United States Fish and Wildlife Service found that the species is "not warranted" for listing as an endangered species thanks to the hard work of volunteers, scientists, and resource managers. The chirps and ribbits of the Relict Leopard Frog is now heard at night in dozens of sites which it had likely occupied historically but been extirpated (locally pushed to extinction) from.

Where next? 
The fight against extinction remains, and dozens of organisms throughout the desert southwest are still threatened due to habitat alteration, invasive species introductions, and global climate change. What happens to these species isn't in the hands of bureaucrats or pompous elected officials. It is largely in the hands of every day people. Ordinary people whose names you likely haven't heard have helped save two of these three species from extinction for now. While many other species have already become extinct or remain threatened, the future of these "libraries of knowledge" remains up to us.

The fires are burning close to the doors of these libraries. What will you do?

References and further reading:

Deacon, James E., and Joshua E. Williams. "Retrospective evaluation of the effects of human disturbance and goldfish introduction on endangered Pahrump poolfish." Western North American Naturalist 70.4 (2011): 425-436.

Bradford, David F., Jef R. Jaeger, and Randy D. Jennings. "Population status and distribution of a decimated amphibian, the relict leopard frog (Rana onca)." The Southwestern Naturalist 49.2 (2004): 218-228.

Miller, Robert R., James D. Williams, and Jack E. Williams. "Extinctions of North American fishes during the past century." Fisheries 14.6 (1989): 22-38.

Proactive conservation keeps Relict Leopard Frog off the endangered species list. http://www.grandcanyonnews.com/news/2016/nov/15/proactive-conservation-keeps-relict-leopard-frogs-/



No comments:

Post a Comment