Ha. Roditi et al., CHARACTERISTICS OF ZEBRA MUSSEL (DREISSENA-POLYMORPHA) BIODEPOSITS INA TIDAL FRESH-WATER ESTUARY, Archiv fur Hydrobiologie, 140(2), 1997, pp. 207-219
Zebra mussels are now a major component of the benthos in the tidal fr
eshwater Hudson River. Their filtering activity has had a wide range o
f ecosystem-level effects. Zebra mussel biodeposits (feces and pseudof
eces) were sampled in in situ chambers containing mussels attached to
artificial substrates. The biodeposits collected were analyzed for org
anic matter (OM), chlorophyll-a, phaeopigments, C, N, bacterial cell d
ensities, and bacterial production rates. Relative to control sediment
s (sediments passively collecting in the chambers), biodeposits were s
ignificantly enriched in all measures except bacterial cell densities.
Biodeposits were estimated to contain 9.5 % OM and 3.9 % live algae b
y weight, while values in passive deposits were 7.8 % and 1.1 %, respe
ctively. The C:N ratio of biodeposits was estimated at 8.3, and bacter
ial production was estimated at 14.6 x 10(7) cells gOM(-1) h(-1), whil
e passive deposit values were 9.8 and 7.4 x 10(7) cells gOM(-1) h(-1),
respectively. When subjected to a range of mixing energies, biodeposi
t 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 wate
r currents in a system like the tidal freshwater Hudson River will red
uce their residence time at the river bottom, possibly reducing their
ecological impact on the benthos.