Characteristics of zebra mussel (Dreissena polymorpha) biodeposits in a tidal freshwater estuary
Roditi, Hudson A.; Strayer, David L.; Findlay, Stuart E. G.
published: Sep 25, 1997
ArtNo. ESP141014002004, Price: 29.00 €
Zebra mussels are now a major component of the benthos in the tidal freshwater Hudson River. Their filtering activity has had a wide range of ecosystem-level effects. Zebra mussel biodeposits (feces and pseudofeces) were sampled in in situ chambers containing mussels attached to artificial substrates. The biodeposits collected were analyzed for organic matter (OM), chlorophyll-a, phaeopigments, C, N, bacterial cell densities, and bacterial production rates. Relative to control sediments (sediments passively collecting in the chambers), biodeposits were significantly enriched in all measures except bacterial cell densities. Biodeposits were estimated to contain 9.5 % OM and 3.9 % live algae by weight, while values in passive deposits were 7.8 % and 1.1 %, respectively. The C:N ratio of biodeposits was estimated at 8.3, and bacterial production was estimated at 14.6x107 cells gOM-1h-1 while passive deposit values were 9.8 and 7.4x107 cells gOM-1h-1, respectively. When subjected to a range of mixing energies, biodeposit mixtures (feces, pseudofeces and passive deposits) were resuspended at a bed stress that was approximately 50 % lower than the bed stress required to resuspend the passive deposits. Although biodeposits were shown to be enriched in the above measures, their resuspension by water currents in a system like the tidal freshwater Hudson River will reduce their residence time at the river bottom, possibly reducing their ecological impact on the benthos.