Freshwater Underwater Clicking Noise. Plankton??

[popolarbear]

similar to the Clicking noise in marine that is caused as i understand by reef fish chewing on corals. we noticed this summer that in afew spots there was a localized high(noisy) area that had a dense clicking. I was at the time thinking it was a gathering of plankton for some reason that was causing the clicking. there was indeed a good amount of free floating daphnia like  organisms.  also of interest this was the one spot along this shoreline that a number of fish were gathering in. mainly large bluegills, bass and afew pike. the rest of this shoreline had just afew small bluegills and occasional odd minnow. ..

my question is has anyone else seen such a phenomenon where in one small area there is some kind of underwater clicking in just one small spot and several fish were gathering around? and does anyone know what this might be caused by?

sound was like dozens of people were clicking their finger nails at the same time.