The amount of water a clam filters is called the clearance rate. This rate is typically measured in liters per hour per gram of clam mass. The clearance rate can decline if the bivalves "clam up" in response to stresses from temperature or salinity. They can also be reduced if the clams' gills are clogged by non-food particles, such as during a storm. The clams may increase clearance rate if they sense more plankton in the water, or if they are trying to bulk up before spawning! #clamfacts