Vol. 53 - Alaska Resources Library and Information Services

parameters measured. Clams from the first post-spill sampling had the lowest number of
associated pairs and the greatest inter-bay diversity. Clams from the pre-spill sample
were intermediate. At all three sampling times, there was little association among values
for carbohydrate, lipid and free amino acid parameters. In clams from the first post-spill
sampling, there were no associated pairs shared by Bay 11 (receiving oil alone) and the
other three bays.
4.3 Discussion
There was a high degree of variability in the values for different biochemical
parameters in replicate clams from the same sample, among samples from different bays,
and in samples collected at different times. This variability makes it difficult to identify
biochemical responses of clams to the oil spills. There are several possible explanations
for the observed variability.
Bivalve molluscs, like many other marine invertebrates, typically show a wider
range of normal (unstressed) values for many biochemical parameters than do fish and
other "higher" animals (Newell, 1976; Gabbott, 1976; Carr and Neff, 1981, 1982). In
species such as the mussel Mytilus edulis for which an extensive body of basic biochemical
and physiological information is available (Bayne, 1976), some of this variability can be
accounted for or controlled. There are practically no data available on the normal
biochemistry, physiology, and seasonal cycles of Mya truncata.
Perhaps more important, and a major problem in a remote field experiment of
this sort, are the methods used to sample and handle animals in the field. Mya from the
second post-spill sampling were much more uniform in all biochemical parameters
measured than were clams from the first two collections. It is quite possible that this was
due in part to differences in handling of the animals by the field collecting teams. A
substantial time delay between collecting the clams and freezing them can result in large
and unpredictable changes in several of the biochemical parameters studied, particularly
concentrations of tissue glucose and free amino acids. Ideally, samples should be frozen
in liquid nitrogen or dry ice immediately upon collection. This was not feasible in the
BIOS study. Although samples apparently were frozen within a few hours of collection in
most cases, notes in the collecting log book indicate that some samples were held
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