download 21.6mb - Oil-Spill-Info.com

epresented an inflammatory response to a stressful condition and
therefore a pathology due to such stress, or if it was a normal condition
in the reproductive cycle of C. gigas. This condition was present
in only one Cvassostvea virginica from South Louisiana oil platforms
(Armstrong et al., 1980) but was observed in other bivalve species (10%
of specimens examined in association with degeneration or necrosis of
the gonad). Eight female C. gigas from the Pacific Northwest (Sequim,
Washington) were examined for comparison. All eight appeared to be in
a post-spawn condition and all had heavy aggregation of leucocytes in
the gonadal tissues.
The spawning cycle of the C. gigas from France could not be definitely
determined. Undifferentiated (could not determine if it was male
or female), undeveloped, developing (immature), ripe (mature) and spawned
stages were present in samples from all five of the collecting periods
(December 1978, April 1979, August 1979, February 1980, and June 1980).
The majority of the specimens from December 1978, however, appeared to
be of the spawned stage at Aber Wrac'h, ripe at Aber Benoit, and undifferentiated
at Rade de Brest. In April 1979, the majority of the specimens
appeared to be in the developing stage at all three sites. The majority
of the specimens taken during August 1979 and June 1980 appeared to be
of the ripe stage at all three sites, although there were some spawned-
appearing specimens from Aber Wrac'h in August 1979. The February, 1980
collection yielded more undifferentiated and developing specimens. This
does somewhat indicate an early winter spawn, but as already stated, all
reproductive
periods.
stages were present in samples from all five collection
In the C. gigas from France, 13.8% (18 of 130) of the gonads
examined contained large numbers of leucocytes dispersed throughout
the tissues. All 18 incidences were in female gonads (18 of 76 or 23.8%).
This condition was present in undeveloped, developing (immature), ripe
and post spawn ovaries. In some cases it could not be determined if the
ovary was in a developing stage or a post-spawn stage because of the
large numbers of leucocytes present. In some, the gonad appeared fully
spawned (entire gonad examined contained only a few ova and ovacytes,
follicles largely empty), while in others part of the ovary was packed
with ova (ripe) and the other part contained few ova and ovacytes
(spawned) and many leucocytes. In gonads with large numbers of leucocytes,
all or almost all ova appeared normal (not degenerating or lysing) ,
The 29 normal ovaries (no aggregations of leucocytes present) included
the undeveloped, developing (immature), ripe and spawned stages.
Twenty-two of the 130 (16.6%) gonads examined contained compact
clumps of leucocytes ranging from foci in the follicular wall to large
281