The potential role of freshwater mussels in reducing Giardia and otherhuman pathogens in watersheds of the Pacific northwest

摘要

Freshwater mussels were abundant in rivers of the Pacific Northwest and were an important source of nutrition for many Native Americans in pre-European times. Since then, populations of freshwater mussels have declined. Habitat changes, pollution and declines in salmon (an important upstream transport vector of larval stages) are likely causes. These declines will result in a reduction in the filtering capacity of mussel populations and removal of suspended sediments and organisms, including the human pathogens Giardia duodenalis and Cryptosporidium parvum. Laboratory studies showed that adult (91-127 mm shell length) freshwater mussels (Margaritifera falcata) filtered mice-derived Giradia (G. muris) at rates of 0.49 1 h super(-1) g super(-1) mussel dry weight. In addition, mussels filtered microalgae [Schizochytrium sp.; in the same size range as G. duodenalis (2.7-7.1 mu m)] at rates of 0.39 to 0.411 h super(-1) g super(-1) dry weight. The filtering action of mussels could be an important natural mechanism for reducing concentrations of human pathogens in streams and rivers.