Does a lake need to have anything special, like clear water, or current to hold shell beds?

If you're talking about mussels/clams, they are filter feeders.  They help keep the water clear.  

All they need is a bottom that they can dig into, and a food source in the water column.  Not sure how sensitive they are temp wise.

I suppose the ph might be a critical factor.

They are more common than I realized.

Are there many Mussels around the Potomac?  I haven't found any yet.  I am going to try finding some shell beds on Tuesday though.

I don't know how they like currents.  Don't know if they are found in rivers.

The problem with a current would be spawning.  In saltwater, the shellfish have to deal with currents.  Each has its own way of either moving or staying put.

Mussels anchor themselves to objects with a byssal thread.  Various clams bury into the bottom.  Scallops are free swimming, but will settle into pockets if they want to stay put when the tide is running.

In saltwater, you have four periods of slack tide each day.  Actually it's a fraction less than that because each tide change takes just over six hours.

In saltwater, the critters can spawn at these times if need be, or when a weak current is flowing to stir up the reproductive materials discharged into the water.  

In a fresh water river, the flow is constant and always in the same direction.

Just don't know if that works for freshwater shellfish or not.

Good observations but keep in mind that the Potomac is tidally influenced so it shares the same characteristics as the salt.  I have found the best concentrations of mussels in channel bends or where the lake or river makes a turn.  This tells me that the mussels tend to like some current in order to bring the nutrients that they are filtering out of the water to them.  I don't have any biological evidence to support this but this is my hypothesis so take it with a grain of salt.

Well down here in central FLA, we've got shell beds in the lakes, retention ponds and way inland on the St. John's river

Good observations but keep in mind that the Potomac is tidally influenced so it shares the same characteristics as the salt. I have found the best concentrations of mussels in channel bends or where the lake or river makes a turn. This tells me that the mussels tend to like some current in order to bring the nutrients that they are filtering out of the water to them. I don't have any biological evidence to support this but this is my hypothesis so take it with a grain of salt.

Do you tend to find them on the inside or outside of the bend, or both?  I know the current tends to scour the outside of the bends, while leaving deposits on the inside.

The inside of the bend, depending on the contour, may have swirling eddies and currents which run counter to the flow of water, which allows for more settling of anything, including spat, and sediments.

I tend to find more on the outside bends but never have been too certain why.  Maybe that is where stuff exits the current flow and settles in that bend?  That is a good question and I would love to know if anyone else knows the true reason for this?  

In this area the Ohio river is full of shell beds, some of those are Zebra mussels and that could be part of the reason the river has been getting clearer over the past several years. I find them on bars and some of the biggest seem to be on the down river points of islands.

Freshwater  mussel and clams need two things, good oxygen content and some current.    Found in rivers, lakes, resorvoirs, and streams.

  Lots of info can be assumed from knowing beds.   Just part of the food chain and plays its role at times during the year.

   

 

 

 

 

   

     

   

 

There are allot of places on the Potmac with shell beds. They are just hard to find now because they are covered with grass