these trilobite particles (nicknamed “Mickey” for obvious reasons) that we determined it was really a eukaryotic algae. Chuck went on to carry out in situ seasonal
studies on Mickey’s inorganic carbon fixation rates and found it contributed ~50%
of annual primary productivity, along with some lab-based studies on its unusually
adaptive physiology, including its ability to grow at very low light levels (Roesler
et al. 2002; Oremland et al. 2017). Much later, Stamps et al. (2018) detected mRNA
sequences of photosynthetic machinery that implied Mickey was still carrying out
“cryptic” oxygenic photosynthesis at depths below the lake’s pycnocline where there
was no detectable light. Mickey was also capable of forming a variety of organoarsenic compounds, including an unusual 2-O-methyl riboside lipid which was
transmitted via “trophic transfer” (i.e., eating) to the lake’s brine shrimp (Glabonjet
et al. 2020).
Once upon a time, maybe 30 years ago, I could snorkel around the tufa towers in
Mono Lake and the water was crystal clear. The winter bloom of Mickey in the
surface water had been consumed by the first emerging generation of brine shrimp
(Artemia), and by the summer, they had pretty much cleared out the lake’s green
color. Other than the brilliant white of the submerged tufa and the hordes of brine
shrimp, there wasn’t much to see. Mono Lake is a simple ecosystem and is too
chemically extreme to host fish or other invertebrates besides brine flies. The only
interesting facet are the many migrating waterfowl that sojourn on the lake to feast
on brine shrimp and flies to fuel their long seasonal voyages north or south, and they
can be viewed comfortably from the boat. Indeed, snorkeling in Mono Lake has its
hazards, as you definitely do not want to get lake water in your eyes or in your throat,
as it has a burning sensation on delicate tissues. So I had to put fresh water in my
mask (to guard it from fogging) and in my snorkel as well and remember never to
dunk my head below the surface, thereby replacing the snorkel’s freshwater with
Mono water. SCUBA diving is even worse, as one must use extra weights to
compensate for the salinity buoyancy factor, and submerged freshwater springs
can represent a real hazard as an over-weighted diver would soon encounter low
density freshwater and be forced to quickly drop one’s weights or be drawn to one’s
death into the maw of the spring itself.
Yet over recent years, we noticed that Mono Lake’s surface water is always green
and turbid, hosting a perpetual bloom of Picocystis. The reason(s) for this are not
clear, but because productivity in the epilimnion is usually nitrogen-limited (there is
an abundance of phosphate ~1 mM) it could be due to: (1) a decrease in Artemia
filter-feeding or (2) perhaps an input of key nutrients (N) to the surface waters that
were previously constrained by thermal or salinity density stratification. The latter
could arise from a linked biological source (N 2 -fixation) or from wet/dry atmospheric deposition (e.g., ash fall from California’s recent mega-fires) or decade-long
drought-driven dust inputs or again from spring stream runoff from the Sierra
snowmelt.
Testable hypotheses for the next generation of interested young scientists to
tackle.
31 Salty, Alkali-Laced Tales (Mostly True) from the Great Basin Desert, California. . .
669
studies on Mickey’s inorganic carbon fixation rates and found it contributed ~50%
of annual primary productivity, along with some lab-based studies on its unusually
adaptive physiology, including its ability to grow at very low light levels (Roesler
et al. 2002; Oremland et al. 2017). Much later, Stamps et al. (2018) detected mRNA
sequences of photosynthetic machinery that implied Mickey was still carrying out
“cryptic” oxygenic photosynthesis at depths below the lake’s pycnocline where there
was no detectable light. Mickey was also capable of forming a variety of organoarsenic compounds, including an unusual 2-O-methyl riboside lipid which was
transmitted via “trophic transfer” (i.e., eating) to the lake’s brine shrimp (Glabonjet
et al. 2020).
Once upon a time, maybe 30 years ago, I could snorkel around the tufa towers in
Mono Lake and the water was crystal clear. The winter bloom of Mickey in the
surface water had been consumed by the first emerging generation of brine shrimp
(Artemia), and by the summer, they had pretty much cleared out the lake’s green
color. Other than the brilliant white of the submerged tufa and the hordes of brine
shrimp, there wasn’t much to see. Mono Lake is a simple ecosystem and is too
chemically extreme to host fish or other invertebrates besides brine flies. The only
interesting facet are the many migrating waterfowl that sojourn on the lake to feast
on brine shrimp and flies to fuel their long seasonal voyages north or south, and they
can be viewed comfortably from the boat. Indeed, snorkeling in Mono Lake has its
hazards, as you definitely do not want to get lake water in your eyes or in your throat,
as it has a burning sensation on delicate tissues. So I had to put fresh water in my
mask (to guard it from fogging) and in my snorkel as well and remember never to
dunk my head below the surface, thereby replacing the snorkel’s freshwater with
Mono water. SCUBA diving is even worse, as one must use extra weights to
compensate for the salinity buoyancy factor, and submerged freshwater springs
can represent a real hazard as an over-weighted diver would soon encounter low
density freshwater and be forced to quickly drop one’s weights or be drawn to one’s
death into the maw of the spring itself.
Yet over recent years, we noticed that Mono Lake’s surface water is always green
and turbid, hosting a perpetual bloom of Picocystis. The reason(s) for this are not
clear, but because productivity in the epilimnion is usually nitrogen-limited (there is
an abundance of phosphate ~1 mM) it could be due to: (1) a decrease in Artemia
filter-feeding or (2) perhaps an input of key nutrients (N) to the surface waters that
were previously constrained by thermal or salinity density stratification. The latter
could arise from a linked biological source (N 2 -fixation) or from wet/dry atmospheric deposition (e.g., ash fall from California’s recent mega-fires) or decade-long
drought-driven dust inputs or again from spring stream runoff from the Sierra
snowmelt.
Testable hypotheses for the next generation of interested young scientists to
tackle.
31 Salty, Alkali-Laced Tales (Mostly True) from the Great Basin Desert, California. . .
669