Long story:

2nd year into renovating/managing older sand pit. Limed last March. Struggled getting appropriate bloom and fought algae summer of 2017. Changed fertilizer for 2018 (increased P fert). Worked good. Had decent bloom but not 24", no algae problem water is really pretty.

Starting about 2 weeks ago:
bloom looked really good, seemed to be getting better. Following trip noticed water looked extremely green and vis had gone to around 2 feet. Not brown but looked like a great bloom. Also noticed what looked like white blooms from some plant floating on the water. Didn't pay a lot of attention. Next trip investigated and it was muscles floating dead on the water. Hundreds of them. Enough that as they have collected along the bank and started to rot it's very a noticeable smell. No fish floating at all anywhere, haven't even found a floater all summer. I know its possible for a drop in oxygen levels to kill shad and muscles and not be enough to affect fish. Very few small fish and all my bigger BG are no longer visible around the dock or banks. I don't have any shad so I don't know for sure if this is the case. We are in the dog days of August, dry, hot, and evaporation rate is very high. Water level has probably dropped 10 +/- inches total over the month of August.

Anyone ever seen this happen?

I saw something like this earlier this summer. I had some, not a lot, of 1/2" long clam-like muscles that floated around the pond. My assumption was that the muscles were floating to the surface with a minor outbreak of FA mats. I saw the muscles on the mats and I also saw them floating solo. It never dawned on me that they might have been dead so I never checked. This went on for maybe a few weeks. I raked some FA a time or two then the FA subsided and the muscles were not to be seen floating around anymore.

I never had any dead fish, but the pond clarity at the time, IIRC, was poor and there were bagillions of bullfrog tadpoles. It would not surprise me if my DO2 was on the dangerous side.

Calling any muscle experts. Just a bump to get some attention.

Don't RES eat mussels?

yes res will eat mussels - so do white drum

Thanks!

Bump...

Algae toxins can kill both vertebrates and invertebrates. There are associated with severe blooms. They even have an acronym for it. "HAB" or harmful algae bloom. Likely your culprit.