Vol. 53 - Alaska Resources Library and Information Services

polychaetes in both June and August and overall. In the corrected
overall diet, four taxa, Pectinaria sp (a polychaete), sand dollars,
sabellid polychaete worms, and the clam, Tellina sp, account for 92% of
the soft tissue dry weight. Comparing June and August shows the June diet
dominated by polychaetes (45%) and sand dollars (47%) and the August diet
dominated by polychaetes (70%) and clams (19%).
CALORIC INTAKE
Caloric intake was calculated with values from the literature (Table
18) and from laboratory determinations (Table 19). Attempts to determine
the caloric values for whole sand dollars both before and after digestion
with 0.01 M HCL failed because of incomplete combustion of the sample even
after mixing with benzoic acid. The caloric value for sand dollars used
in the calculations was from bomb calorimetry of viscera after dissection
from the test (Table 19).
Using the June and August daily rations, 6.30 and 11.92 mg dry weight
per gram crab wet weight per day, and the corrected dietary composition
based on soft tissue dry weights.(Table 16 and 17) the daily rations were
converted to calories. Floc dominated the dry weight of stomach contents
and, being organic matter, has caloric value. Clearly, floc must be
considered in estimating the daily intake of calories, but how floc should
be considered in such estimation was not obvious.
One can consider the source of the floc to be one of two extremes. At
one end floc is taken to derive entirely from unidentified prey items
different from those already identified and for which soft tissue dry
weights were calculated. At this extreme the caloric value of the floc is
in addition to that of the identified prey items and must be included in
any calculations of total caloric intake. At the other extreme floc is
taken to derive entirely from the soft tissue of the prey items already
identified and for which soft tissue dry weights have been taken into
account. At this extreme the caloric value of the floc is equal to that
calculated from the soft tissue dry weights of the identified prey and
should not be included in any calculations of total caloric intake.
To encompass these extremes total caloric intake was estimated under
three assumptions: first, that floc could not be attributed to any of the
other items already identified and had a caloric value equal to the mean
of all the invertebrates identified as prey items; secondly, that floc was
diluted by inorganic matter or derived equally from known and unknown prey
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