Topic summary
Oligotrophic lake
Extracted from the Wikipedia article Trophic state index.
Oligotrophic
In this way, oligotrophic lakes can have significant oxygen down to the depth to which the aforementioned seasonal mixing occurs, but they will be oxygen deficient below this depth. Therefore, oligotrophic lakes often support fish species such as lake trout, which require cold, well-oxygenated waters. The oxygen content of these lakes is a function of their seasonally mixed hypolimnetic volume. Hypolimnetic volumes that are anoxic will result in fish congregating in areas where oxygen is sufficient for their needs.