Globally, lake waters are thought to be getting darker due to increasing concentrations of dissolved organic carbon - an amalgam of thousands of uncharacterized carbon compounds that get flushed into lakes from surrounding areas. It's been predicted that this change in water color will lead to declining fish populations, but prior studies haven't considered how variations in lake depth might affect this relationship.
Seekell, D. A., P. A. Byströn, & J. Karlsson 2018. Lake morphometry moderates the relationship between water color and fish biomass in small boreal lakes. Limnology and Oceanography. Early Online. DOI: 10.1002/lno.10931