Fig 4.

Reductions of C. parvum oocyst concentrations and water turbidity caused by the clams and rates of water filtration by the clams at various water temperatures and feed densities. Means and standard deviations are shown based on results from seven replicates. The absence of bars indicates that the error was smaller than the symbol. (A) Results obtained using laboratory water at 20°C. ●, oocyst density with both clams and feed (28 mg/liter); ○, oocyst density with clams but without feed; , oocyst density without clams or feed; ▲, turbidity with both clams and feed; , turbidity without clams but with feed. (B) Results obtained using final settling pond water at 20°C. ●, oocyst density with clams; , oocyst density without clams; ▲, turbidity with clams; , turbidity without clams. (C) Water filtration by clams at various water temperatures and feed densities. See Materials and Methods for details of calculation of the water filtration rate (in L/h).