Buse Lake is a shallow(3-6 metres) alkaline pond..pH 12. Every 10 years or so it becomes totally oxygen depleted. The water becomes port wine colored and the area has a very strong smell of H2S. Samples were taken from bottom silt and the upper 12 inches of water. The silt sample was well populated with resting phase rotifer eggs. Samples with eggs were placed in freshwater and observed for 1 week..2 were photographed in the hatching phase (Later pictures) Other unusual organisms will also be uploaded at a later date.
I think that these should probably be called resting cysts. This is apparently the form they revert to in order to survive adverse conditions. They are said to be able to survive for months in this state. Once conditions improve they rehatch and start again.
This body of water is far to small and too shallow to cause the inversions that you allude to. The smell of sulfur in this case comes from anerobic bacteria/metabolizing sufur containing compounds and releasing H2S