Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

including brown and brook trout, Atlantic salmon, bass, tunicates (sea squirts), and a
saltmarsh grass (Spartina spp.). Estimates suggest that over 90 species have been
intentionally or accidentally introduced in the region (Ruckelshaus and McClure 2007).
At present, over 40 species in the region are listed as threatened and endangered under
the ESA.
Puget Sound is unique among the nation’s estuaries as it is a deep fjord-like structure that
contains many urban areas within its drainage basin (Collier, O'Neill et al. 2006).
Because of the several sills that limit entry of oceanic water into Puget Sound, it is
relatively poorly flushed compared to other urbanized estuaries of North America. Thus,
toxic chemicals that enter Puget Sound have longer residence times within the system.
This entrainment of toxics can result in biota exposure to increased levels of contaminant
for a given input, compared to other large estuaries. This hydrologic isolation puts the
Puget Sound ecosystem at higher risk from other types of populations that enter the
system, such as nutrients and pathogens.
Because Puget Sound is a deep, almost oceanic habitat, the tendency of a number of
species to migrate outside of Puget Sound is limited relative to similar species in other
large urban estuaries. This high degree of residency for many marine species, combined
with the poor flushing of Puget Sound, results in a more protracted exposure to
contaminants. The combination of hydrologic and biological isolation makes the Puget
Sound ecosystem highly susceptible to inputs of toxic chemicals compared to other major
estuarine ecosystems (Collier, O'Neill et al. 2006).
An indication of this sensitivity occurs in Pacific herring, one of Puget Sound’s keystone
forage fish species (Collier, O'Neill et al. 2006). These fish spend almost all of their lives
in pelagic waters and feed at the lower end of the food chain. Pacific herring should be
among the least contaminated of fish species. However, monitoring has shown that
herring from the main basins of Puget Sound have higher body burdens of persistent
chemicals (e.g., PCBs) compared to herring from the severely contaminated Baltic Sea.
Thus, the pelagic food web of Puget Sound appears to be more seriously contaminated
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