|Abstract or Summary
- The purpose of this study was to develop a marine bioassay
procedure using eggs and larvae of Pollicipes polymerus, a stalked
barnacle common on the west coast of North America.
A series of experiments were run to determine optimal culture
conditions for the eggs, to see if they could be grown without antibiotics,
and to generate the necessary data on development time,
hatching, and molting success required to design future experiments.
Next, two bioassays were run to determine how the system
performed in actual use. A phthalate ester plasticizer, dibutyl
phthalate (DBP), was used as the test compound. The first of these
experiments indicated there was a significant drop in molting success
from larval stage I to stage II when eggs were exposed to 1000 ppb
DBP. Variances in molting success, sometimes high in previous
experiments, became unacceptable in this one, so the next experiment
was designed to reduce these variances by more accurately identifying
the time of first egg hatching.
The end point used in previous experiments (3 days after first
hatching) proved to be insufficient for enough of the controls to
molt and, therefore, no conclusions could be drawn on the effects of
DBP. The experiment did indicate how excessive variance in molting
success could be avoided in future experiments, and how overall
molting success could be improved. Hatching successes obtained in
all these experiments compared favorably to those obtained by
While testing the synthetic seawater used in the experiments for
background phthalate levels, it was found that several phthalates,
particularly DBP and diethylhexyl phthalate (DEHP) were persistent
contaminants. Dibutyl phthalate levels could be reduced by treatment
with activated charcoal.
Tests were conducted to determine how much DBP remained in
solution between water changes. Dibutyl phthalate loss was found to
increase with increasing initial DBP concentration, but DBP loss from
this system over 24 hours compared favorably to that observed in a
similar experiment employing larval marine crustaceans.
A design for equipment to culture P. polymerus in vitro and
suggestions for conducting bioassay studies with eggs and larvae are