Assabet River NWR Final CCP - U.S. Fish and Wildlife Service

Chapter 3: Refuge and Resource Descriptions
a central Massachusetts location; and
morphology, pH, alkalinity, trophic status, and watershed
characteristics similar to Puffer Pond.
Surface water and sediment sample pairs were collected at six locations in
each pond. Fish samples were collected at four locations in each pond, using
gill nets, angling, and electroshocking. Chain pickerel were sampled as
predators, yellow perch as foragers, and bullheads as bottom feeders.
During actual sampling, four bullheads were the only bottom feeders
collected in Ministers Pond. In the predator and bottom feeding levels,
fillet concentrations were used to calculate human health risks, and whole
fish concentrations were used to determine ecological risks. In the forager
level, only whole fish samples were analyzed.
In water samples from Puffer Pond, arsenic, cadmium, and lead were
detected at concentrations above the screening values. Concentrations of
those metals were below the screening values in all of the background pond
surface water samples. However, the maximum lead concentration in the
Puffer Pond samples was only slightly higher than the maximum
concentration detected in the background pond.
In sediment samples, arsenic concentrations exceeded the screening value
in all Puffer Pond samples, whereas only one of the background samples
exceeded the arsenic screening value. Concentrations of cadmium, lead,
silver, and the pesticides DDD and DDE exceeded the
respective screening values at approximately the same
frequencies in samples from both ponds.
Mercury was not detected in surface water or sediment
from either pond at concentrations above the laboratory
method detection limits (0.2 ug/l and 0.1 ug/g, respectively).
Although mercury was not detected in surface water or
sediment, it was detected in 14 of 24 fish from Puffer Pond
and in 17 of 19 fish from Ministers Pond. Mercury exceeded
the USFDA action level (1.0 mg/kg) in only one fish (a
Beaver activity: Photo by Marijke Holtrop
yellow perch from Puffer Pond), at a concentration of 1.12
mg/kg. Concentrations of mercury, arsenic, chromium, and lead in Puffer
Pond fish samples “were not statistically different from local background
conditions” (E&E 1994).
E&E concluded that potential human health risks associated with eating
fish from Puffer Pond are negligible and that potential ecological and
human health risks are no greater than those posed by Ministers Pond or
other similar ponds in the area. Despite low environmental concentrations,
mercury is bioavailable to aquatic organisms. The fish are a primary food
source for piscivorous wildlife and “may result in allowing the contaminants
to magnify in the food chain as they are generally consumed whole” (E&E
1994).
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