When a lake initially gets zebras in it the population explodes exponentially at first, then it hits a carrying capacity and the numbers drop and level off. There was an extensive study done on Mille Lacs regarding this. I havent seen a recent update, but the numbers eventually fall but it first those buggers and spreading like wildfire.
Yup, I’ve watched our cabin lake go through this. When we bought in ’09 it was zeeb free, then they showed up in ’11 and they were everywhere within a year or two – noticeable changes in fish patterns, although water clarity seemed the same. Weeds got thicker and deeper, “green blob” filamentous algae increased in the spring to where it covered almost all the bottom near shore and then became floating bubbly, slimy mats by early summer. But in recent years, the zeebs are less prevalent. Weeds are still thicker than they used to be, but the Filamentous Algae isn’t as bad, and we’re catching fish in areas and frequency more like we did in ’09. I’ll have to look up the mercury levels but I think they’re about on-par with the average.