Studies on the Use of Raw Water by Dreissena Polymorpha Pallas
Gunnison, Karen L.
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The use of raw (unprocessed) water by the zebra mussel (Dreissena polymorpha) was investigated through analysis of the bacterial population of sediment suspended in raw water versus that found in mussel biodeposits (feces and pseudofeces). According to the findings, raw water filtered by the mussels contained a single dominant species, tentatively identified as Pseudomonas paucimobilis B; the mussel biodeposits were more variable, with no apparent dominant species. Disappearance of bacteria from raw water over the observed period and the absence of these bacterial species from pseudofecal samples indicate that the mussels ingest bacteria and suggest that they also digest the cells. Removal of bacteria and s~spended sediment from surrounding water was found to follow an exponential curve, consistent with earlier studies on filtration of artificial pellets and algae. The presence of Aeromonas hydrophila-like DNA Group 2, lanthinobacterium lividom A, and Aeromonas media-like DNA Group 5 (tentative) in both the fecal bacteria and the visceral mass indicate that some component of the fecal bacteria may be supplied by the mussels' intestinal flora. The presence of Pseudomonas mephitica and Pseudomonas putida B (tentative) in pseudofeces and their absence in all other fractions indicated contamination from the mussels.