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PCB Elimination by Yellow Perch (Perca flavescens) during an Annual Temperature Cycle
journal contribution
posted on 2007-02-01, 00:00 authored by Gordon Paterson, Kenneth G. Drouillard, G. Douglas HaffnerThe significance of temperature on aquatic species
ecology and physiology is well recognized yet its effects
on chemical bioaccumulation kinetics are less well understood
under natural conditions. In this study, yellow perch
were dosed with a polychlorinated biphenyl (PCB) mixture
and allowed to depurate the chemicals over 1 year
under an ambient temperature cycle characteristic of
northern temperate latitudes. PCB elimination kinetics during
the summer months at optimal water temperature for
perch (23 °C) were similar to those observed in lab studies
with other species reared at their optimal temperature.
During the fall and winter seasons, however, elimination
of only 11 PCB congeners of log Kow ≤ 5.7 was observed and
half-lives averaged >1000 d for these PCBs. PCB
elimination was again observed with the onset of spring
temperatures but elimination rates averaged 2.6 times slower
for readily metabolized congeners and 7.5 times slower
for more persistent PCBs than observed during the summer.
Bioenergetics modeling efforts predicted maximum
values for respiration, fecal egestion, and growth rates
during summer months but also predicted rapid declines
in these chemical dilution processes during the fall and winter
concurrent with changes in temperature. As temperature
increased into the spring, bioenergetic rates were predicted
to increase but only achieved ∼85% of maximum rates
predicted for summer peak temperatures. These results
indicate that minimal chemical elimination occurs in perch
when metabolic functioning falls to low maintenance
levels during the fall and winter. These seasons encompass
approximately 8 months of the year at northern temperate
latitudes and therefore these patterns have significant
consequences for understanding mechanisms of food-web biomagnification of hydrophobic organic chemicals
in aquatic systems.