Vol. 53 - Alaska Resources Library and Information Services

oil residues in the gut and muscle tissue are different. The more water-soluble aromatics
(naphthalene, alkylated benzenes) are transported to the muscle tissues (including gills)
more rapidly, with the phenanthrenes and dibenzothiophenes preferentially located in the
gut. During the first two weeks after the spill, however, it is these higher molecular
weight aromatics which persist, the water-soluble aromatics being depurated more
readily.
Initial levels of oil in filter-feeders from Bay 7 are equal or greater than those
from Bays 9 and 10, where water column levels of oil were 20 to 200 times as great.
Sediments are ruled out as an oil-biotal intermediary due to the near absence of oil in
Bay 7 sediments. Thus one must postulate that while Mya and Serripes from Bays 9 and 10
either cease pumping due to water column levels or die after initial accumulation of oil,
animals in low-to-moderately contaminated waters continue to pump and acquire oil as
long as it is present in the water. At water column concentrations of 50 µg/l (50 ppb), a
clam (1 g dry weight) pumping at a rate of 1 liter per hour would pass 1.2 mg of oil
through its body in 24 hours, more than enough to acquire a 100-500 ppm concentration.
As levels of oil in Bays 9 and 10 were much higher, 1-50 ppm initially and 100-200 ppb for
at least a day to a day and a half after cessation of the oil spillage, opportunities for
greater bioaccumulation in Bays 9 and 10 were available but were probably not achieved
due to either saturation in the gut, inability to transport oil across the membranes fast
enough to acquire more oil, or a wholesale cessation of pumping. The latter explanation is
the most likely.
Mya truncata and Serripes groenlandicus are filter-feeders and accumulate oil
primarily from the water column. They depurate 60-75 percent of the accumulated oil
within two weeks, even though the sediments in which they reside remain contaminated
with oil. On the other hand, Macoma calcarea and Nuculana minuta are deposit-feeders,
and accumulate petroleum hydrocarbons primarily from the sediments. In controlled
laboratory experiments, Roesijadi et al. (1978) showed that the deposit-feeder, Macoma
inquinata, accumulated higher concentrations of aromatic hydrocarbons from Prudhoe Bay
crude oil-contaminated sediments than did the filter-feeder, Protothaca staminea. In the
BIOS study, the deposit-feeders continued to accumulate hydrocarbons during the two
weeks after the spill (Bays 9 and 11) or became heavily contaminated immediately after
the spill and retained the hydrocarbons for at least two weeks (Bay 7 and 10). The GC 2
61