Freshwater Underwater Clicking Noise. Plankton??

[popolarbear]

ive heard this in several lakes since i first noticed it. the spot that realy got my attention was in Lake Sylvia on the edge of the cities. there was a spot that dropped from maybee 6ft with weeds and lilypads to over 20ft deep with 20ft vis. by the way the weeds in the lake are increadibly deep. some spots i think the weed mats are 8-15ft in deepth. i sank down in one spot so deep in weed without hitting bottom that it freaked me out!
anyways definitly not drum. and ive been in spots Thick with crayfish and never noticed any effect but will keep an eye out next time. im realy under the impression the sound effect was from some kind of invertebrate like plankton or perhaps aquatic insect larvae. it was realy loud and isolated in one spot because as i moved around it had a strange direction and localization, as much as is possible underwater. and what got me currious is that a number of fish were kinda pilled up in this area. in particular was that i noticed pike only in that spot.