A 3-year investigation of sexual reproduction in Geodia cydonium (Jameson 1811) (Porifera, Demospongiae) from a semi-enclosed Mediterranean bay


Mercurio, M.; Corriero, G.; Gaino, E.

Marine Biology 151(4): 1491-1500

2007


The reproductive cycle of Geodia cydonium in a semi-enclosed Mediterranean bay (Porto Cesareo, SW Apulia) was studied with monthly frequency over a 3-year period. The investigation was carried out by utilizing a technique consisting of tagging ten individuals with a PVC stick and cutting off, by means of a metal cork borer, small samples (cylinders about 5 cm3 in volume) from each of them for histological analysis. Sexual reproductive elements were detected in all individuals, but in the third year some specimens showed reduced reproductive activity or complete infertility. Spermatogenesis occurred in a short period (from June to August) whereas oogenesis lasted longer (from spring to late summer). Spermatic cysts occurred when the frequency of specimens with oocytes reached its maximum values. A relationship between water temperature and the onset of gamete differentiation was observed. G. cydonium is here confirmed oviparous and gonochoric with a sex ratio in favour of the females. However, in contrast with current literature on Porifera-which suggests that only a limited number of sponges, all belonging to the same species are sexually active-the sexual reproduction of this species involves all the examined individuals. This finding can be explained by the methodological approach used in this research, which differs from the traditional way of assessing the sponge reproductive cycle by analysing randomly collected specimens within a population. The study of a series of individuals over time represents a better "model technique" for investigating sponge sexual reproduction and the effect of environmental parameters on gamete differentiation.

Mar
Biol
(2007)
151:1491-1500
DOI
10.1007/s00227-006-0584-x
RESEARCH
ARTICLE
A
3-year
investigation
of
sexual
reproduction
in
Geodia
cydonium
(Jameson
1811)
(Porifera,
Demospongiae)
from
a
semi-enclosed
Mediterranean
bay
M.
Mercurio
G.
Corriero
E.
Gaino
Received:
31
May
2006
/
Accepted:
8
December
2006
/
Published
online:
9
January
2007
©
Springer-Verlag
2007
Abstract
The
reproductive
cycle
of
Geodia
cydonium
in
a
semi-enclosed
Mediterranean
bay
(Porto
Cesareo,
SW
Apulia)
was
studied
with
monthly
frequency
over
a
3-year
period.
The
investigation
was
carried
out
by
uti-
lizing
a
technique
consisting
of
tagging
ten
individuals
with
a
PVC
stick
and
cutting
off,
by
means
of
a
metal
cork
borer,
small
samples
(cylinders
about
5
cm
3
in
vol-
ume)
from
each
of
them
for
histological
analysis.
Sex-
ual
reproductive
elements
were
detected
in
all
individuals,
but
in
the
third
year
some
specimens
showed
reduced
reproductive
activity
or
complete
infertility.
Spermatogenesis
occurred
in
a
short
period
(from
June
to
August)
whereas
oogenesis
lasted
longer
(from
spring
to
late
summer).
Spermatic
cysts
occurred
when
the
frequency
of
specimens
with
oocytes
reached
its
maximum
values.
A
relationship
between
water
temperature
and
the
onset
of
gamete
differentiation
was
observed.
G.
cydonium
is
here
confirmed
ovipa-
rous
and
gonochoric
with
a
sex
ratio
in
favour
of
the
females.
However,
in
contrast
with
current
literature
on
Porifera—which
suggests
that
only
a
limited
num-
ber
of
sponges,
all
belonging
to
the
same
species
are
sexually
active—the
sexual
reproduction
of
this
species
involves
all
the
examined
individuals.
This
finding
can
Communicated
by
R.
Cattaneo-Vietti,
Genova.
M.
Mercurio
G.
Corriero
(21)
Dipartimento
di
Zoologia,
University
degli
Studi
di
Bari,
Via
Orabona,
4,
70125
Bari,
Italy
e-mail:
g.corriero@biologia.uniba.it
E.
Gaino
Dipartimento
di
Biologia
Animale
ed
Ecologia,
University
degli
Studi
di
Perugia,
Via
Elce
di
Sotto,
06123
Perugia,
Italy
be
explained
by
the
methodological
approach
used
in
this
research,
which
differs
from
the
traditional
way
of
assessing
the
sponge
reproductive
cycle
by
analysing
randomly
collected
specimens
within
a
population.
The
study
of
a
series
of
individuals
over
time
represents
a
better
"model
technique"
for
investigating
sponge
sex-
ual
reproduction
and
the
effect
of
environmental
parameters
on
gamete
differentiation.
Introduction
Numerous
aspects
of
reproduction
have
been
investi-
gated
over
the
years
in
several
species
of
marine
sponges,
with
particular
attention
to
the
cytodifferentia-
tion
of
gametes
(see
review
in
Fell
1983;
Simpson
1984;
Gaino
et
al.
1986;
Sara
1992;
Gaino
and
Sara
1994),
but
little
is
known
about
the
reproductive
efforts
and
pat-
terns
of
anatomical-histological
changes
in
sponges.
The
traditional
way
to
assess
the
sponge
reproduc-
tive
cycle
is
based
on
histological
and
ultrastructural
sections
of
specimens
randomly
collected
within
a
pop-
ulation
throughout
the
year
(Levi
1951;
Vacelet
1964;
Chen
1976;
Fell
and
Jacob
1979;
Tanaka
and
Watanabe
1990;
Kaye
and
Reiswig
1991;
Meroz-Fine
and
Ilan
1995;
Corriero
et
al.
1998;
Boury-Esnault
1999;
Eres-
kovsky
2000;
Sidri
et
al.
2005).
The
percentage
of
sam-
ples
undergoing
reproduction
found
in
most
of
these
studies
is
often
so
low
that
it
leaves
open
the
possibility
that
individuals
have
cyclic
breeding
periods,
e.g.
func-
tioning
first
as
males,
then
switching
to
egg
production
(Simpson
1980).
Nevertheless,
as
different
individuals
are
usually
examined
at
each
sampling
period,
there
is
no
means
of
knowing
whether
reproduction
is
an
annual,
biannual,
or
multi-annual
event,
or
whether
it
Springer
1492
Mar
Biol
(2007)
151:1491-1500
there
is
a
lag
in
the
reproductive
timing
within
the
pop-
ulation.
This
procedure
by
itself
inadequately
outlines
the
gametogenic
cycle
and
often
the
type
of
sexuality
cannot
be
rigorously
established
(Ayling
1980).
In
con-
trast,
Ayling
(1980),
Wapstra
and
van
Soest
(1987)
and
Usher
et
al.
(2004)
reported
valuable
information
on
the
sexual
cycle
of
some
demosponges
obtained
from
investigating
tagged
individuals
over
time.
Notwithstanding
literature
data,
which
report
hun-
dreds
of
recordings
of
the
demosponge
Geodia
cydo-
nium
worldwide,
the
only
investigation
on
the
reproductive
cycle
of
this
sponge
is
limited
to
one
Southern
Italian
population
(Scalera
Liaci
and
Sciscioli
1969).
This
study
proved
that
this
species
is
oviparous,
thereby
widening
the
knowledge
on
the
oviparous
sponges,
which
are
notoriously
very
scarce
(Scalera
Liaci
et
al.
1971;
Fromont
1988;
Watanabe
and
Masuda
1990;
Rose111996;
Mariani
et
al.
2000;
Sidri
et
al.
2005).
We
present
here
the
reproductive
cycle
of
ten
appropriately
tagged
specimens
of
G.
cydonium,
which
were
investigated
over
a
3-year
period
in
a
semi-
enclosed
bay
located
along
the
Italian
coast
at
Porto
Cesareo
(SW
Apulia,
Ionian
Sea).
In
addition,
since
sea
water
temperature
appears
to
play
a
pivotal
role
on
the
sponge
reproductive
process
(Diaz
1973;
Reiswig
1983;
Simpson
1984;
Fell
1993;
Witte
et
al.
1994;
Fro-
mont
1999;
Ereskovsky
2000),
this
parameter
was
also
recorded
in
order
to
assess
its
relationship
with
the
reproductive
cycle
of
this
species.
Materials
and
methods
Description
of
the
study
site
Porto
Cesareo
bay
(South-western
Apulia,
South
Italy-40°15'N;
17°54'E)
(Fig.
1)
measures
2,500
m
in
length
and
700-800
m
in
width,
with
a
maximum
depth
of
2.5
m
(Passeri
1974).
The
bay
communicates
with
the
sea
through
a
channel
system
that
allows
a
consid-
erable
inflow
of
sea
water.
The
water
movement
within
the
bay,
however,
is
significantly
lower
than
in
the
open
sea
(Corriero
1990).
The
bottom
consists
primarily
of
mixed
sands;
though
calcareous
substrates,
rocks
and
pebbles
are
also
present.
Thirty-nine
species
of
demo-
sponges
occur
in
Porto
Cesareo
bay
showing
high
cov-
erage
values
(Corriero
1990;
Corriero
et
al.
1996b;
Mercurio
et
al.
2001).
Species
studied
Geodia
cydonium
(Jameson
1811)
is
a
well
known
demosponge,
which
is
very
common
in
the
Atlantic-
SOUTHER/4
ITALY
l()R
TSAR
ItIONIAN
SEA
Fig
1
Porto
Cesareo
bay
(SW
Apulia,
40°15';
17°54')
and
sam-
pling
area
(black
circle)
Mediterranean
area
(Uriz
1981).
This
species
has
been
described
as
very
variable
in
shape:
irregularly
massive
(Uriz
1981),
cushion-encrusting
(Pulitzer-Finali
1983),
spherical
or
sub-spherical
(Corriero
1987),
columnar/
cylindrical
(Morn
et
al.
1994);
its
surface
can
be
smooth
or
grooved
and
is
frequently
covered
by
epibi-
otic
flora
and
fauna
or
by
sediment
(Mercurio
et
al.
2006);
the
consistency
is
usually
hard
and
compact.
The
external
colour
is
whitish
or
grey
and
yellowish
inside.
Specimens
are
very
variable
in
dimensions;
gener-
ally
the
mean
diameter
is
about
10-20
cm,
but
larger
specimens
are
also
reported.
The
largest
specimen
col-
lected
in
the
North
Adriatic
Sea
was
29
kg
in
weight
and
180
cm
in
diameter
(Santucci
1922).
This
species
is
char-
acterized
by
a
peculiar
stratification
of
its
tissue:
a
thick
external
coriaceous
cortex
which
protects
a
soft
internal
choanosome.
The
cortical
layer
is
about
2
mm
thick,
but
is
thinner
in
the
area
of
external
openings
(cribrous
area).
At
Porto
Cesareo
G.
cydonium
is
a
very
common
species.
The
specimens
are
irregularly
massive,
with
brain-like
surface,
and
mainly
settle
on
calcareous
rocky
substrates,
at
a
depth
of
1-2
m,
in
the
middle
part
of
the
basin
(Mercurio
et
al.
2006).
The
results
of
a
sur-
vey
performed
in
the
same
study
area
during
2002
indi-
cated
a
mean
density
for
this
species
of
0.47
±
0.075
specimen/m
2
with
a
fairly
wide
volume-class
distribu-
tion
ranging
between
about
800
and
8,000
ml
(Mercurio
et
al.
2006).
The
mean
volume
of
the
47
specimens
Springer
Mar
Biol
(2007)
151:1491-1500
1493
collected
during
this
study
was
2,050.21
±
2,850.72
ml,
ranging
from
3.0
to
12,500
ml
(Mercurio
et
al.
2006).
According
to
Parenzan
(1976),
in
this
environment,
G.
cydonium
can
grow
up
to
1
m
in
diameter.
Sampling
Within
an
area
of
approximately
100
m
2
,
ten
large
specimens
(ranging
in
volume
from
about
1
to
8
litres)
of
G.
cydonium
(Fig.
2a)
were
selected
and
tagged
with
PVC
coloured
sticks.
For
histological
investigations,
from
October
1995
to
September
1998,
a
metal
cork
borer
was
used
monthly
by
SCUBA
divers
to
cut
off
from
each
specimen
a
small
fragment
of
the
sponge
body
(a
cylinder
about
5
cm
3
in
volume).
The
sponge
tissue
soon
regenerated
and
1
month
later
the
surface
of
the
cut
sponge
appeared
as
a
light
depression
com-
pletely
covered
by
new
cortex.
Concomitantly,
water
temperature
was
measured
monthly
by
using
a
porta-
ble
probe
DELTA
OHM,
HD
8706.
The
study
of
the
reproductive
cycle
was
carried
out
on
histological
sections
(5
um
thick)
obtained
from
samples
embedded
in
paraffin.
For
these
observations,
sponge
fragments
were
fixed
in
4%
formaldehyde
in
sea
water,
immediately
after
collection.
Then
they
were
desilicified
with
15%
hydrofluoridic
acid
in
artifi-
cial
sea
water
for
1.5
h,
dehydrated
in
ethanol
and
embedded
in
paraffin.
Sections,
obtained
by
using
a
Reichert-Jung
2030
microtome,
were
stained
with
tolu-
idine
blue.
For
each
specimen,
examined
under
a
light
microscope,
several
parameters
were
recorded,
as
fol-
lows:
presence/absence
of
gametes,
mean
diameter
and
mean
volume
of
oocytes
(not
including
pseudopodia)
and
sperm
cysts
(assuming
both
to
be
spherical),
the
density
(number/mm
3
)
of
reproductive
elements
and
the
corresponding
percentage
of
sponge
tissue
involved
in
reproduction.
The
calculation
of
the
invest-
ment
in
reproduction
was
carried
out
by
using
a
cam-
era
lucida
coupled
with
an
optical
microscope
and
projecting
histological
sections
on
graph
paper.
This
technique
allowed
us
to
trace
the
surface
of
each
sec-
tion.
The
dimension
of
each
area,
whether
including
gametes
or
not,
was
then
recorded
with
a
KURTA
IS/
ADB
digitizer
connected
to
a
PC.
The
corresponding
volume
was
calculated
by
multiplying
the
surface
of
each
histological
section
by
the
thickness
of
the
section
(5
um).
The
quantitative
evaluation
of
the
density
of
the
reproductive
elements
was
carried
out
using
the
Abercrombie
formula
(1941)
as
suggested
by
Elvin
(1976).
The
formula
is:
d
=
N
x
(t/D
+
t)
(k),
where
d
is
the
density,
N
is
the
number
of
gametes
observed
in
each
histological
section,
t
is
the
thickness
of
the
sec-
tion
(5
um),
D
is
the
diameter
of
the
reproductive
enti-
ties
(mean
value
for
each
specimen
obtained
by
measuring
the
diameter
of
ten
reproductive
elements)
and
(k)
is
a
constant
factor
converting
the
volume
of
each
section
to
1
mm
3
.
Results
Description
of
sexual
elements
The
sponge
fragments,
each
about
5
cm
3
in
volume,
consist
of
a
thick
superficial
cortical
layer
(2
mm)
and
of
an
inner
choanosomal
region,
which
represents
the
most
extended
portion
of
the
fragment.
Only
the
cho-
anosomal
region
is
involved
in
gamete
differentiation.
In
the
early
phase
of
differentiation,
the
oocytes
of
G.
cydonium
measure
about
10-15
um;
they
show
a
large
nucleolated
nucleus
and
a
very
translucent
cyto-
plasm
owing
to
the
lack
of
yolk
(Fig.
2b).
As
gamete
maturation
proceeds,
oocytes
reach
their
maximum
diameter
of
40-45
um,
and
have
pseudopodia
emerging
from
their
peripheral
border
(Fig.
2c,
arrows).
Oocytes
can
often
be
observed
fairly
close
to
one
another
and
separated
by
mesohyl
elements
and
collagen
(Fig.
2c).
Their
cytoplasm
is
gradually
enriched
by
stored
mate-
rial
that
also
fills
the
pseudopodia
(Fig.
2c).
Spermatic
cysts
measure
from
about
25
to
40
um
(Fig.
2d).
Sperm
differentiation
takes
place
asynchro-
nously
since
gametes
can
be
observed
in
different
phases
of
maturation
in
the
same
specimen.
Sexual
cycle
Over
the
3-year
period
of
observations,
oocytes
were
found
in
eight
individuals
of
G.
cydonium
(specimens
1-7,
9),
and
sperm
cysts
were
found
in
the
remaining
ones
(specimens
8,
10).
None
of
the
individuals
showed
the
coexistence
of
oocytes
and
sperm
cysts.
These
data
confirm
the
gonochoric
condition
of
this
species
and
indicate
a
sex
ratio
favouring
female
sponges.
Trends
in
the
sexual
cycle
of
the
specimens
over
the
monitoring
period
are
summarised
in
Fig.
3
a,
b,
c.
For
female
lineage,
the
onset
of
gamete
differentiation
differs
from
year
to
year.
Indeed,
in
the
first
year
of
observation
(October
1995-September
1996),
female
reproductive
elements
were
found
in
April
in
three
of
the
monitored
specimens,
where
they
occupied
0.03%
of
the
sponge
choanosomal
region
and
the
last
ele-
ments
were
observed
in
August
in
eight
individuals,
occupying
0.15%
of
this
sponge
region.
The
highest
reproductive
effort
was
observed
in
July
where
all
the
female
individuals
showed
oocytes
in
0.20%
of
their
choanosomal
region.
In
this
month,
oocytes
reached
it
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Fig
2
a
Tagged
specimens
of
G.
cydonium
(n
=
10)
in
the
study
area.
b
Oocyte
of
G.
cydonium
in
the
early
phase
of
differentiation.
c
Mature
oocytes
with
globous
pseudopodia
(arrows)
emerging
from
their
peripheral
border.
d
Spermatic
cysts
in
the
choanosomal
region
the
mean
maximum
size
of
38
gm
(maximum
size
=
55
gm
recorded
in
the
individual
6).
In
the
second
year
(October
1996—September
1997)
female
gametes
were
observed
in
June
in
three
indi-
viduals,
occupying
0.09%
of
the
choanosome,
and
the
last
ones
in
September
in
four
specimens,
occupying
0.004%
of
this
region.
Although
August
was
the
month
in
which
the
frequency
of
reproductive
female
specimens
reached
the
highest
values,
the
widest
areas
of
occupied
tissue
was
recorded
in
July
(0.20%),
when
oocytes
measured
31
gm
(mean).
In
the
third
year
(October
1997—September
1998)
oogenetic
activity
was
limited
to
three
months,
from
June
to
August.
The
highest
frequency
of
specimens
with
oocytes
occurred
in
July
whereas
the
highest
extent
of
the
sponge
choanosome
occupied
by
female
elements
(0.10%)
was
in
August,
when
they
show
a
mean
diam-
eter
of
26
gm.
The
gamete
dimensional
trend
and
the
percentage
of
sponge
choanosomal
region
they
occupied
over
the
Springer
100
-
a
90
80
70
60
-
2e
50
40
30
20
10
0
1 1 1 1 1
Mar
Biol
(2007)
151:1491-1500
1495
Fig
3
Sexual
cycle
trend
of
G.
cydonium
over
the
study
peri-
od.
a
Monthly
frequency
of
specimens
with
oocytes
and
sperm
cysts
and
seasonal
vari-
ations
of
water
temperature
in
the
study
area.
b
Mean
monthly
tissue
fraction
(percentage
±
standard
er-
ror)
of
sponge
occupied
by
ga-
metes
(%
volume).
c
Mean
monthly
diameter
standard
error)
of
gametes
O
specimens
with
oocytes
35
IM1specimens
with
spermatic
cysts
—A—
water
temperature
30
25
20
P
15
10
5
U
1
1 1
1
1 1 1 1
U1
1 1 1 1 1 1 1 1 1
II
1
0
gig4,10144iSgaLWIMSM420144*2
1995
1996
1997
1998
0
oocytes
IN
sperm
cysts
M4,10*V
4
MMIMA*14
4
MMMA*14
4
N
1995
1996
1997
1998
0.4
0.3
0.2
0.1
0
50
C
0
oocytes
0
sperm
cysts
40
i
30
I
t
I
20
10
0
1 1 1 1
1
I
1 1
1
1 1 1 1 1 1 1 1
1
1 1 1
1
1
1
1
144,1,14
4
MV142014
,3
418114,1014
4
.
1
0;
1995
1996
1997
1998
3-year
period
of
monitoring
are
reported
for
each
indi-
vidual
in
Fig.
4.
Analysis
of
the
data
shows
that
there
is
a
marked
decrease
not
only
in
the
frequency
of
reproductive
specimens
but
also
in
the
duration
of
the
reproductive
period.
This
is
particularly
evident
in
four
individuals
(1,
2,
5,
6)
where
a
gradual
reduction
was
evident
from
the
first
to
the
third
year;
in
the
individual
4,
this
reduc-
tion
is
evident
by
comparing
the
second
with
the
third
year;
in
the
individual
7,
by
comparing
the
first
and
the
second
year.
In
the
remaining
individuals
(3,
9),
repro-
ductive
activity
increased
in
the
second
year,
followed
by
a
decrease
in
the
third
year.
As
far
as
the
sperm
cysts
are
concerned,
they
were
only
found
in
two
individuals
(8,
10).
The
period
of
their
presence
overlaps
in
the
first
2
years,
occurring
from
June
to
August,
but
in
the
individual
8,
gameto-
genesis
was
slightly
de-phased
and
started
in
July.
In
the
third
year,
this
individual
was
the
only
one
having
sperm
cysts
in
July.
In
this
month,
cyst
size
showed
the
highest
values:
a
mean
of
37
gm
in
the
first
year
(maxi-
mum
size
=
62.5
gm
recorded
in
sample
8),
29
gm
in
the
second,
and
33.6
gm
in
the
single
individual
in
the
third
year.
The
percentage
of
choanosome
occupied
by
sperm
cysts
varied
from
a
mean
of
0.21
in
the
first
year
to
0.11
in
the
second,
and
0.07
in
the
single
individual
it
Springer
SPECIMEN
1
A
tissue
fraction
occupied
by
oocytes
0
oocytes
mean
diameter
O
0.6
60
0.5
50
0.4
5.
40
ae
0.3
t
30
0
0.2
g
20
0.1
10
O
0
A
A
Mar
Biol
(2007)
151:1491-1500
SPECIMEN
6
A
tissue
fraction
occupied
by
oocytes
0
oocytes
mean
diameter
0.6
0.5
0.4
0.3
0.2
A
A
A
0.1
0
sX'XA'XXXP0kPPPRA'NNVA'
Jk
a.
ik
r•
e.tiks,
4
0.
r• r•
SPECIMEN
7
0
oocytes
mean
diameter
0.6
A
tissue
fraction
occupied
by
oocytes
0.5
0.4
0.3
0.2
0.1
A
0
sA'sXPkkkkPiRA'A'A'A'A'
-z
4
1.1
4
414
1
14
4
4
,
t41.1
4
44
4
SPECIMEN
2
0
oocytes
mean
diameter
(1)
tissue
fraction
occupied
by
oocytes
0
A
A
XX2RA'XPkk0PkNPRRNA°
SPECIMEN
3
0
oocytes
mean
diameter
tissue
fraction
occupied
-
by
oocytes
A
A
A
AA
XssMPPPPkki
,
?A'A'A'A'A'
nq-f
-1414'.“
441
SPECIMEN
4
0
oocytes
mean
diameter
A
A
1496
40
30
120
10
0
60
50
40
41
30
1
20
10
0
60
50
40
t
30
0
g
20
10
0
A
tissue
fraction
occupied
by
sperm
cysts
t
30
1
20
XXXXkk0000NNNA'A'N
4
1
14-Infinq-f
4414
1
1-f
44/
O
(
1
)
A
A
10
A
0
A
0.6
60
0.5
50
0.4
40
0.3
0.2
0.1
0
0.6
60
-
05
50
-
0.4E40-
0.3
30
-
ae
0.2
1
20
-
0.1
0
A
tissue
fraction
occupied
A
by
oocytes
(1)
(1)
_
'1)
A
30
0
g
20
10
0
10
-
SPECIMEN
8
o
sperm
cysts
mean
diameter
A
-
0.6
-
0.5
-
0.4
-
0.3
-
0.2
-
0.1
A
A
0 0
XXA'sX0PkWA'A'A'A'A'A'
4.
'14441.4.1R-1414.14-111
0.6
60
0.5
50
0.4
ae
0.3
I
30
0
0.2
4
20
0.1
10
O
0
SPECIMEN
9
O
oocytes
mean
diameter
A
tissue
fraction
occupied
by
oocytes
A
A
0.6
0.5
0.4
0.3
0.2
0.1
0
A
A
XA'sX'skPPPPkiRVA'NNA'
4
.
14
4
114
.
14
4
4
,
44
.
1-f
441
P0kPPk
iff
iff
iff
4
.
144414'14-Infin414441
SPECIMEN
5
0
oocytes
mean
diameter
A
tissue
fraction
occupied
by
oocytes
0.6
60
0.5
50
0.4
3.
--
40
0.3
t
30
0.2
1
20
0.1
10
O
0
SPECIMEN
10
0
sperm
cysts
mean
diameter
0.6
0.5
0.4
0.3
50
tissue
fraction
occupied
by
sperm
cysts
40
d
30
1
2
°
10
0
0
A
A
A
A
A
0.2
0.1
0
XXXsWPPkkkkiRIPPRA'A'
4
.
44
4
114
.
44
4
414
.
44
4
41
47.1.f
4
4
,
14'44-
1
1
,
t4'14-
1
1
,
t
Fig
4
Gamete
dimensional
trend
(mean
values
±
standard
deviation)
and
monthly
tissue
fraction
(%)
occupied
for
each
individual
of
Geodia
cydonium
monitored
Springer
Mar
Biol
(2007)
151:1491-1500
1497
in
the
third
year.
As
observed
for
oogenesis,
spermato-
genesis
gradually
reduced
during
this
last
period.
Relationship
between
water
temperature
and
sexual
reproduction
The
mean
water
temperatures
recorded
in
the
study
area
over
the
3-year
period
of
investigation
were
19.6°C
during
the
first
year,
20.9°C
during
the
second
year
and
22.1°C
during
the
last
year.
The
lowest
temperatures
were
registered
in
February
during
the
first
2
years
(10.9
and
13.5°C,
respectively)
and
in
January
in
the
third
year
(15.4°C).
July
always
showed
the
maximum
temperature:
27.3;
27.9;
30.3°C,
respectively
(Fig.
3a).
The
comparison
between
the
water
temperature
val-
ues
and
the
reproductive
cycle
of
G.
cydonium
shows
that
during
the
first
2
years,
the
onset
of
oogenesis
(presence
of
small
oocytes)
took
place
concomitantly
with
a
sharp
increase
in
the
water
temperature
(about
5°C
in
the
first
year
and
7°C
in
the
second),
which
occurs
during
late
spring
(from
April
to
June)
(Fig.
3a).
The
maximum
reproductive
effort
(highest
frequency
of
reproductive
specimens
and
maximum
diameter
of
oocytes)
occurred
in
summer
(from
June
to
August)
when
water
temperature
values
were
beyond
25°C.
Males
occurred
from
June
to
August,
concomitantly
with
the
maximum
effort
of
the
sponge
in
oocytes
pro-
duction
(Fig.
3a).
In
contrast,
during
the
third
year,
female
and
male
sexual
activity
showed
a
short
over-
lapping
period
at
the
highest
water
temperature
recorded.
Discussion
The
technique
used
in
the
present
investigation,
based
on
the
employment
of
a
marker
for
sampling
the
same
individual
over
time,
allowed
us
to
confirm
the
gonoch-
oric
condition
of
G.
cydonium.
This
is
in
agreement
with
previous
observations
on
sampling
carried
out
randomly
within
a
sponge
population
(Scalera
Liaci
and
Sciscioli
1969).
Neither
embryos
nor
larvae
were
observed
in
the
sponge
tissue,
thereby
confirming
that
the
species
is
oviparous,
a
condition
already
ascer-
tained
by
Scalera
Liaci
and
Sciscioli
(1969).
Our
methodological
approach
shows
that
sexual
reproduction
occurs
with
seasonality:
the
oogenetic
cycle
starts
in
late
spring
and
stops
at
the
end
of
sum-
mer.
As
the
oogenesis
proceeds,
the
number
of
individ-
uals
with
oocytes
increases
along
with
the
increase
of
oocyte
dimensions.
Female
gametes
should
be
released
when
they
measure
40-45
um,
the
maximum
value
recorded
in
the
studied
specimens.
Spermatic
cysts,
deriving
from
choanocyte
chambers
(Scalera
Liaci
and
Sciscioli
1969),
occur
for
a
short
period
concomitantly
with
the
highest
intensity
of
the
oogenesis.
This
sexual
pattern,
also
reported
for
other
demosponges
(Scalera
Liaci
et
al.
1971,
1973;
Tanaka
and
Watanabe
1990;
Fell
1993),
probably
represents
the
most
common
means
of
sexual
reproduction
among
oviparous
sponges
in
temperate
seas.
The
occurrence
of
sperm
cysts
in
only
two
of
the
ten
sponges
suggests
a
sex
ratio
in
favour
of
females,
a
con-
dition
that
seems
to
be
fairly
common
among
Porifera
(Scalera
Liaci
et
al.
1971;
Wapstra
and
Van
Soest
1987;
Corriero
et
al.
1996a,
1998;
Mercurio
et
al.
2000;
Meroz-Fine
et
al.
2005).
The
literature
reports
that
the
annual
reproductive
index
in
sponges
is
usually
low,
with
only
a
limited
number
of
specimens,
generally
not
exceeding
50%,
able
to
differentiate
gametes
(Scalera
Liaci
et
al.
1973;
Corriero
et
al.
1996a,
1998).
Scalera
and
Sciscioli
(1969)
reported
for
G.
cydonium
an
annual
reproduc-
tive
index
of
38.1%
with
a
peak
of
reproductive
speci-
mens
in
August
(58%).
Therefore,
it
is
quite
surprising
that
all
the
individuals
of
G.
cydonium
monitored
in
the
present
study
reproduce
for
two
consecutive
years
out
of
the
three
investigated.
It
is
well
known
that
gam-
ete
production
in
sponges
varies
from
individual
to
individual,
probably
according
to
age
and
size
(see
Simpson
1980
for
a
review).
Indeed,
it
has
been
fre-
quently
observed
that
the
relative
amount
of
resources
put
into
reproduction
increases
with
age
(Graham
1985).
Here
we
intentionally
selected
the
ten
speci-
mens
of
G.
cydonium
among
the
larger
individuals
to
minimize
the
effects
of
sampling,
indirectly
biasing
this
study
towards
specimens
with
increased
probability
of
sexual
activity.
Nevertheless,
we
believe
that
the
meth-
odology
used
in
the
present
paper,
if
extended
to
a
wider
number
of
specimens
of
various
sizes,
could
rep-
resent
a
better
approach
for
studying
reproductive
pro-
cesses
in
sponges
and
should
be
considered
in
future
investigations
on
this
subject.
However,
better
knowl-
edge
of
the
sponge
reproduction
from
studying
tagged
specimens
has
also
been
demonstrated
by
Usher
et
al.
(2004)
who
investigated
Chondrilla
australiensis,
previ-
ously
studied
by
Fromont
(1999).
The
study
of
tagged
individuals
has
established
a
better
definition
of
the
details
of
reproduction
in
this
species,
including
the
reproductive
nature
of
this
sponge,
the
timing
and
fre-
quency
of
gametogenesis
and
spawning
and
details
of
the
biology
of
the
developmental
process.
In
G.
cydonium,
the
percentage
of
choanosomal
tis-
sue
occupied
by
gametes
is
low
and
fairly
similar
in
females
and
males
(maximum
values
observed,
0.48
and
0.37%,
respectively),
whereas
in
other
oviparous
it
Springer
1498
Mar
Biol
(2007)
151:1491-1500
species
such
as
C.
australiensis
(Usher
et
al.
2004)
and
Chondrilla
nucula
(Sidri
et
al.
2005),
a
higher
energy
investment
in
reproduction
has
been
observed
with
a
consistent
reduction
in
the
aquiferous
system
which
appears
to
seriously
deplete
the
nutritional
status
of
the
sponge.
By
contrast,
in
viviparous
species,
such
as
Tedania
anhelans
(Nonnis
Marzano
et
al.
2000)
and
Pellina
semitubulosa
(Mercurio
et
al.
2000),
the
density
of
sperm
cysts
is
far
higher
than
that
of
the
oocytes.
The
data
here
recorded
show
that
in
G.
cydonium
the
onset
of
reproduction
does
not
occur
simulta-
neously
in
all
individuals.
In
particular,
oocytes
are
often
present
in
spring
whereas
spermatogenesis
occur
later
on.
However,
we
cannot
exclude
that
these
oocytes
can
grow
slowly
and
remain
longer
in
the
sponge
tissue.
The
time
of
onset
of
sexual
activity
in
the
many
indi-
viduals
varied
over
the
3
years
of
study.
A
slight
asyn-
chrony
in
the
reproduction
within
the
same
population
has
been
previously
described
for
other
sponge
species
(Bergquist
1978;
Corriero
et
al.
1998).
The
mechanisms
controlling
the
onset
and
lasting
of
reproduction
and
gamete
growth
are
still
scarcely
known.
However,
many
authors
emphasize
the
relationship
between
vari-
ations
in
sexual
activity
and
different
environmental
conditions
(Storr
1964;
Rader
and
Winget
1985;
Wap-
stra
and
van
Soest
1987;
Pronzato
and
Manconi
1991;
Pronzato
et
al.
1993).
Indeed,
among
the
exogenous
factors
affecting
sponge
reproduction,
water
tempera-
ture
appears
to
exert
an
important
role
by
affecting
the
reproductive
cycle
of
various
species
of
Porifera
(Storr
1964;
Simpson
1968,
1984;
Diaz
1973;
Fell
1976,
1993;
Ereskovsky
2000;
Meroz-Fine
et
al.
2005).
A
relation-
ship
between
the
increase
in
water
temperature
and
the
timing
of
sexual
reproduction
has
been
described
for
Cliona
vastifica
(Hartman
1958),
Haliclona
loo-
sanoffi
(Hartman
1958;
Wells
et
al.
1964;
Fell
1976),
Hippospongia
lachne
(Storr
1964),
Petrosia
ficiformis
(Lepore
et
al.
1995),
Mycale
contarenii
(Corriero
et
al.
1998)
and
C.
australiensis
(Usher
et
al.
2004).
In
the
studied
individuals
of
G.
cydonium,
young
oocytes
are
evident
in
April
and
June,
when
water
temperature
suddenly
increases
by
several
degrees.
Egg
growth
proceeds
during
the
warmer
season
when
sperm
differentiation
also
takes
place.
This
trend,
markedly
overlapping
during
the
first
2
years,
changes
in
the
summer
of
the
final
year,
possibly
because
of
an
unusual
event
of
water
warming,
which
affects
sponge
metabolism
(Zocchi
et
al.
2003).
It
is
thus
very
likely
that
water
temperature
plays
a
pivotal
role
in
also
controlling
the
reproductive
cycle
of
G.
cydonium.
A
further
hypothesis
on
the
decrease
in
reproductive
activity
could
be
linked
to
the
costs
of
the
regenera-
tive
processes
in
sponges
subjected
to
such
a
long
period
of
disruptive
sampling.
Tissue
regeneration
in
sponges
is
a
well
known
phenomenon,
which
starts
immediately
after
cutting
(Pronzato
et
al.
1999;
Corri-
ero
et
al.
2004),
and
generally
leads
to
a
rapid
repara-
tive
processes
(Simpson
1984).
Several
studies
demonstrate
that
the
rapid
regeneration
observed
after
experimental
wounding
is
important
to
prevent
fouling
of
exposed
skeletal
elements
(Leys
and
Lau-
zon
1998;
Duckworth
2003),
to
maintain
competitive
superiority
in
space-limited
systems
(Jackson
and
Palumbi
1979),
to
reattach
if
fragmented
(Wilkinson
and
Thompson
1997)
and
to
regain
optimal
size
and
shape
for
feeding
(Bell
2002).
In
Geodia
barretti
explants
derived
from
choanosomal
tissue
regener-
ated
into
healthy
sponges,
equalling
the
original
weight
approximately
after
6
weeks.
In
addition
the
development
of
eggs
cells
in
cultivated
fragments
demonstrate
that
G.
barretti
is
able
to
continue
its
reproductive
cycle
despite
manipulation
and
reduc-
tion
in
size
(Hoffmann
et
al.
2003).
In
G.
cydonium,
tissue
samples
of
approximately
10
g
cultivated
for
the
extraction
of
bioactive
metabolites
formed
a
robust
contact
with
the
cultivation
trays
after
just
2-3
days.
Moreover,
two
pieces
of
tissue
from
the
same
sponge
placed
in
close
contact
fused
together
after
2-3
days,
demonstrating
the
high
regenerative
capacity
of
this
species
(Muller
et
al.
1999).
As
a
consequence,
the
monthly
sampling
of
small
fragments
(5
cm
3
in
vol-
ume)
collected
from
large
specimens
of
G.
cydonium
should
not
be
responsible
for
the
decrease
in
sexual
activity
observed
in
the
third
year.
Acknowledgments
This
work
was
financially
supported
by
the
Italian
Ministeri
dell'Economia
e
delle
Finanze,
dell'Istruzione,
dell'Universita
e
Ricerca,
dell'Ambiente
della
tutela
del
Territo-
rio,
delle
Politiche
Agricole
e
Forestali
funds
(Prog.
M.I.C.E.N.A.).
All
the
experiments
complied
with
the
current
Italian
laws.
We
are
very
grateful
to
the
anonymous
referees
for
their
helpful
suggestions,
which
remarkably
improved
the
content
of
the
paper.
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