Sunday, August 31, 2014

Climate Stability Threatens to Eliminate Bait

Sheepshead Minnow
Approximately 10,000 years ago, just after the end of the last glacial maximum, and it's subsequent rebound in the Younger Dryas event, in a long vanished wet and lake filled Southwest, a drying climate trapped a population of the common Sheepshead Minnow (Cyprinodon variegatus), or something very much like it
in a small, hot geothermal spring in Nevada, where, isolated from it's fellows, and subject to extreme heat and chemical conditions, it evolved into the Devil's Hole Pupfish (Cyprinodon diabolis), which still looks a whole lot like a Sheepshead Minnow:

Devil's Hole Pupfish
Now, according to scientists, the climate, which has not changed in the last 17, almost 18 years according to the satellite data set RSS, threatens the little fellow with extinction:

Climate change puts endangered Devils Hole pupfish at risk of extinction
Climate change is hurting reproduction of the endangered Devils Hole Pupfish, threatening the survival of this rare species that has numbered as few as 35 individuals, new research by the University of Nevada, Reno and Desert Research Institute shows.

Scientists report that geothermal water on a small shelf near the surface of an isolated cavern in the Nevada desert where the pupfish live is heating up as a result of climate change and is likely to continue heating to dangerous levels.

The hotter water, which now reaches more than 93 degrees, has shortened by one week the amount of time pupfish larvae have to hatch during the optimal recruitment periods. The recruitment period is the 10 weeks during which water temperatures are conducive to egg hatching and sufficient food is available to sustain the newly hatched larvae. This decrease contributed to the decline of the adult pupfish population, according to a scientific paper published in Water Resources Research, a journal of the American Geophysical Union.
Yes, climate change is definitely a threat to the Devil's Hole Pupfish. Extinction is what often happens when a species evolves in a limited habitat to unusual (and borderline lethal) conditions. Mother Nature has no sense of mercy, or direction, and is likely to either change conditions in a harsher direction which ultimately kills of the species, or relents, and causes its habitat to rejoin the larger population it evolved from, where it faces the possibility of having to compete with the parent population, which may also lead to its extinction, too. Or, it may find itself in a new niche in which it might live in relative peace, not competing with the parent species or it's descendants.

The lesson here is not that climate change can and should be stopped; any look at time beyond normal human scales shows that climate changes, a lot, for reasons we don't yet fully understand. The danger is having your species needs too narrow. I don't think that, in general, human beings fall into that trap, although specific civilizations have.

The temperature and salinity tolerant, and food adaptable Sheepshead Minnow continues to thrive around the country. Their primary value is food for larger fish (not present in Devil's Hole), and to be sold as bait.

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