Distribution and dynamics of shell-‐boring Polydora on Crassostrea gigas
Abstract
The
proportion
of
live
Crassostrea
gigas
infected
with
Polydorid
spionid
worms
was
surveyed
at
several
locations
around
San
Juan
Island.
Thirty
infected
C.
gigas
were
collected
from
the
Argyle
Lagoon
locations
and
worm
galleries
and
holes
on
the
inside
and
outside
of
shells
were
counted
and
assigned
to
a
shell
region.
The
proportion
of
borings
that
penetrate
the
inner
layer
of
nacre
was
calculated.
The
area
of
each
shell
region
was
determined
to
find
the
density
of
worm
populations
and
shells
were
cut
to
measure
the
thickness
of
different
regions.
Oyster
populations
with
the
highest
proportion
of
infected
individuals
also
had
higher
per-‐
shell
population
densities.
The
proportion
of
nacre
invasions
remained
constant
as
the
population
density
of
worms
varied.
Although
the
average
thickness
of
the
whole
shell
did
not
affect
the
proportion
of
inner
nacre
borings,
the
adductor
scar
and
hinge
regions
showed
a
negative
correlation
between
nacre
bore
holes
and
thickness.
Description
Zoo-Bot Quarter, Spring 2011