3. Results
3.1. Effect of a selectiÕe Õersus a non-selectiÕe feeding behaÕiour on respiration and
ammonia excretion rates
Mussel respiration and ammonia excretion rates were independent of either a
selective versus a non-selective feeding behaviour ŽFig. 1a and b.. The greatest
respiration rates, which were double the control values Ž p-0.05, ANOVA., were
obtained for those mussels exposed to the highest algae and silt concentrations Ž150=106
cells algaeq50 mgly1 silt.; however, this value was not significantly different from the
two matrices where both selective and non-selective feeding occur ŽArifin and Bendell-
Young, 1997.. Ammonia excretion rates followed the same trend as respiration rates,
with the greatest value occurring under conditions of maximum seston quantity.
However, and as noted for respiration rates, this value was not significantly different
from the seston matrix where a non-selective feeding strategy occurs. Hence, there
appears to be no clear metabolic cost as measured by respiration and ammonia excretion
rates, associated with the extent of a selective feeding behaviour.