Biofouling of wastewater treatment plants by the freshwater bryozoan, Plumatella vaihiriae (Hastings, 1929)

We report large growths of a phylactolaemate bryozoan, Plumatella vaihiriae [Hastings, A. (1929) Notes on some little-known phylactolaematous polyzoa and description of a new species from Tahiti. Ann. Mag. Nat. Hist., 10(3), 300–311], from three widely separated domestic wastewater treatment plants in the United States. This relatively uncommon species is previously known only from Tahiti, Hawaii, Utah, and Argentina. The bryozoan colonies are capable of plugging pipes and filters. Free statoblasts are suspected of interfering with ultraviolet disinfection of wastewater. Laboratory reared specimens exhibit rapid, aggressive growth and produce vast quantities of free statoblasts which either float or sink. Devising effective control methods is impeded by limited knowledge of bryozoan physiology. Given the widespread distribution of known wastewater treatment facilities affected by the bryozoan, the problem is probably a common one.