Sunday, November 15, 2020

The Islands of Interior California (and Nevada): The Endemics of Ash Meadows

Many months ago I was working on a mini-series of blogs about the Islands of Interior California when I was rudely interrupted by a COVID pandemic, and almost all blog writing ceased while I struggled with the transition to teaching online. The next installment was to be about one of the strangest places in the biological sense in all of North America: Ash Meadows. To get this series moving again, I have adapted some previous posts from 2017.
Welcome to one of the most remarkable places in the United States. It's a large island in the middle of the hottest and driest desert in the country. I freely admit that the unprepossessing photograph above is one of the least likely real estate ads ever, but it reveals the landscape of one of the most biologically unique spots in the continental United States, and this picture could have been a real estate ad in the early 1980s.
Crystal Spring at Ash Meadows
Ash Meadows National Wildlife Refuge is not in Death Valley proper, but instead lies about 30 miles east of Death Valley National Park. It is administered not by the National Park Service, but by the U.S. Fish and Wildlife Service. But it does enclose an outlier of Death Valley National Park, and it preserves critical habitat and nearly 30 endemic animal and plant species that were nearly extirpated in the 1970s and 1980s. The fact that it exists at all is entirely due to geology.

During the Pleistocene ice ages during the last two million years, the climate in this dry desert was often cooler and wetter. Rain and snow fell on the high mountain ranges to the north and east and soaked into the ground. Over the millennia the groundwater flowed slowly to the southwest, along river valleys and even through fissures right through mountain ranges. Bedrock ridges and gouge-filled fault lines forced the "fossil water" to the surface as a series of 30 or so seeps and springs. The amount of water flowing here is tremendous; some of the springs have flows measured in thousands of gallons per minute. For example, Crystal Springs in the pictures above and below has a flow of 2,800 gallons per minute. The presence of so much water in the desert makes Ash Meadows an island, but in this case it is an island of water in a landscape of dryness. It is one of the few oases left in the American desert, and has the highest concentration of endemic species in a small area anywhere on the continent.
Water in the desert attracts (and isolates) many kinds of plants and animals (including more than 215 species of birds). Many are survivors, relics of wetter times who could not otherwise live in the desert. That would include the four native species of fish (a fifth is already extinct), and ten species of water snail (an eleventh is also extinct).
The proposed Calvada Lakes development from the 1980s

Water in the desert can be home to invasive species which can do great damage to the fragile ecosystem. Mosquito Fish, which are an important species in other settings, can upset the life balance in the pools and springs. So can abandoned aquarium fish. But the worst invasive species of all, Homo sapiens, nearly destroyed the entire complex.

It happened first when farmers began to manipulate the springs into irrigation systems. They piped the water flows and started pumping groundwater so intensely that the water table started to drop, threatening the species that lived in the ponds. Lawsuits ensued and one eventually reached the Supreme Court. In 1976, the court ruled that pumping had to be limited to the extent that water tables would not drop. The farming corporation sold the properties to a land developer, which led to an even greater threat to Ash Meadows.

The real estate development is in retrospect nearly unbelievable: more than 30,000 homes, along with shopping centers, casinos, theatres, and industrial parks. An instant city in the midst of barren desert. Even today, I can't imagine 50,000 people or more simply deciding to move out to the middle of nowhere. "But Las Vegas!" is an obvious response, but other desert town developments have faltered and disappeared when people realized how truly miserable the summer temperatures could be (and that's not to mention the winter winds and dust storms). Calvada Lakes would have been a disaster on so many levels.
Luckily, Congress stepped in and established the Ash Meadows National Wildlife Refuge in 1984, and most of the developer's lands were purchased by the Nature Conservancy in 1986. The lands were then re-sold to the federal government, and the refuge became a reality. Today, there is a marvelous new visitor center and three handicapped accessible boardwalks that explore some of the most interesting springs.
Devil's Hole Pupfish
The rain was still falling when we arrived at the refuge during our recent Bombogenesis trip to the Death Valley region. It had indeed been falling all night, so I should have known what was going to befall us when we tried to drive the gravel-clay road to Devil's Hole to see the most restricted vertebrate habitat on the planet. The vans very nearly got stuck in the slick mud, and we only made it out by getting out and pushing the van back onto semi-solid ground. We didn't make it, in other words. But we have in the past, and I'm providing a few pictures of the event.

The entire race of the Devil's Hole Pupfish lives in the shallow cavern opening on the side of a limestone hill. The water is constantly warm, almost 90 degrees, is oxygen poor, and the food supply for the fish is extremely limited. But somehow the fish have survived, and have diverged from their relatives who live in pools just a few miles away. They are thought to have been isolated for a minimum of 20,000 years, but some studies suggest as much as 60,000 years (an outlier study takes a different position, suggesting only a few centuries of isolation).

Access to the cave opening is for obvious reasons highly restricted. There is a caged platform from which the pool can be viewed from about 80 feet away. It's clearly hard to see the individual fish, but my camera has a great zoom lens. I'm not sure why they were there (to catch eggs?), but the white tiles in the pool allowed me to catch some video of the rarest fish in the world (below).

The cavern opening where the entire population of Devil's Hole Pupfish lives

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