Laguna Alchichica and the brackish salamander.

Laguna Alchichica (Lake Alchichica) is a deep maar lake (a type of crater lake) in central Mexico, and what makes Alchichica interesting is that it is a hyposaline alkaline lake. Researchers Oliva, Luger, Alcocer, and Cantoral-Uriza, in their survey of Cyclotella choctawhatcheeana (a diatom found in Lake Alchichica), note that the lake’s water is composed of 8.3-9 grams of dissolved salt per liter with an average pH of 8.8-10. Seawater has approximately 35 grams (1.2 oz) of dissolved salts (mostly, but not entirely, the ions of sodium chloride) with a pH of 7.5-8.4 (source: wikipedia). Though not saltier than the ocean, as some believe, Lake Alchichica is still quite saline considering the endemic fauna found within its waters, namely the brackish salamander Ambystoma taylori. It is also home to both an endemic silverside fish, Poblana alchichica, and an endemic copepod, Caecidotea williamsi.

Ambystoma taylori, or Taylor’s Salamander, is an amazing amphibian. Very few amphibians can tolerate brackish water, let alone inhabit it as a primary environment. Taylor’s Salamander is an exception. According to the EDGE of Existence website, it “appears to be specialised for life in saline (or salty) water, as the salinity of Laguna Alchichica which it inhabits is near to the maximum tolerated by most adult amphibians, and is well above that tolerable to eggs and embryos. This salamander will basically eat anything, within reason, that fits into its mouth. It typically hides below the water line under overhangs in the crater’s edge of Laguna Alchichica and is found in very deep water, often more than 30m below the surface.” Like many species in Mexico, Taylor’s Salamander “is seriously threatened by water extraction and diversion from Laguna Alchichica.” In the arid landscape that spans the vast American Southwest to the highlands of Central Mexico, aquatic animals frequently adapt to take advantage of less than ideal (yet available) environments. Unfortunately, these microenvironments are usually very small, limiting the natural range of the adapted species. Cyprinodon diabolis, the Devil’s Hole Pupfish, is perhaps the best-known example of this phenomenon (for more information about C. diabolis, visit their official website here). Microenvironments are highly susceptible to change, and even indirect water usage can wipe out an entire species, or even an entire ecosystem. Cyprinodon nevadensis calidae, a relative of C. diabolis, serves as a reminder of how easily disrupted these microenvironments are…and, despite their adaptibility, how easy it is to lose an entire species or subspecies forever.

In October of 2004, diver Alan Formstone visited Lake Alchichica with the stated goal of photographing Taylor’s Salamander. Despite being plagued with equipment problems, he was successful, and his photos are amazing; you can read about his dive and see the photographs he took posted on his website here (broken link as of 2018). Formstone makes an interesting observation: he reports that the larger salamanders were found in the deeper, colder waters of the lake. This makes sense, as colder water holds more oxygen.