Day 5: Walker Lake, the first project site…

Today our focus was on Walker Lake in Walker Lake, NV. Like Mono Lake, Walker is a closed basin lake that is dominated by carbonate. It too is way down in volume due to agricultural diversion of its headwaters (Walker River). Walker Lake has dropped 140 ft since 1880 and has a long geologic history of draining and refilling over time. This is most apparent by the ancient shorelines clearly visible in the surrounding mountains.

Walker Lake used to have the Lonhontan cutthroat trout in it, but the water quality has dropped so that they all died off about 2 years ago. The Geobiological feature of this lake are the calcium carbonate deposits that are found in, near and above the current lake level. These are laminated, like stromatolites but it is unclear if they were biogenic or abiogenic. This would represent another modern stromatolite that we could study to learn more about how ancient versions were formed. Aside from the stromatolites, there are also features that represent ancient “hard ground” structures. These could be built by or with the interaction of microbes in or on the lake bottom near the shore.

We sampled for chemistry of the groundwater seeping in from the surrounding hills, lakewater, sediments that do not appear to be part of these hard ground structures and the hard ground itself. With the molecular biology, we are hoping to answer the simple question of whether the microbial populations associated with these differ between each other. Also knowing which populations are present will also allow us to hypothesize what metabolisms and other activities are contributing to the environment in which the hard grounds are being produced.  

The hard ground structures are in the foreground, just underwater…