Foo, S.A., Byrne, M.
and Gambi, M.C.
2018
Residing at
low pH matters,
resilience of
the egg jelly coat
of sea urchins living
at a CO2 vent site.
Marine Biology 165: 97,
Doi:10.1007/s00227-018-3359-2.
NOTE:
The ability to evaluate
an organism's adaptive
responses is almost never
factored into laboratory
experiments, because
of time or funding
constraints.
To project the future
existence of a species,
this key response
must not be ignored.
But it almost always is.
Foo et al. (2018)
note that the eggs
of sea urchins
are surrounded
by a "jelly coat"
comprised of
"a polysaccharide
fiber network embedded
in a glycoprotein matrix
that hydrates in contact
with seawater,"
which helps to increase
fertilization success.
Little is known about
how the jelly coat
of sea urchins
might be impacted
by so-called
ocean acidification.
Researchers
investigated
this subject
on the urchin
Arbacia lixula.
SUMMARY:
This study
demonstrates
that organisms
have the power
to adapt, over a
relatively short
time period --
the CO2
venting activity,
causing the
reduced pH site,
has only been
happening for
a maximum
of three decades.
Resilience of the
egg jelly coat
to reduced pH
is good news
for those
worrying about
ocean acidification.
The cross-sectional area
of the jelly coat around
the Arbacia lixula eggs
spawned from urchins
inhabiting the control pH site
declined as the treatment pH
declined (27% and 23%
decline, at pH of 7.7 and 7.5,
respectively, relative to
a pH of 7.9).
In contrast, the size
of the jelly coat was
"unaffected by low pH"
for eggs spawned
from urchins living
at the CO2 vent site.
Foo et al. conclude
with the fact that
"the egg jelly coat
of sea urchins
from the vent site
was robust to low pH,
shows intra-specific
variation in this trait,
and that this difference
may be a maternal
adaptive strategy
or plastic response."
if this response
is common, it
"would facilitate
the maintenance
of gamete function,
facilitating
fertilization success
in a low pH ocean."
DETAILS:
Foo et al. collected
adult specimens
from two locations
off the island
of Ischia (Italy),
the first containing
normal pH waters
(pH of 8.00; the control)
while the second,
approximately 4 km away,
was near a volcanic vent
(the vent site) that reduced
seawater pH to a mean of 7.69.
Within hours of collection,
spawning was induced
and eggs from the control
and vent site were
immediately placed into
seawater pH treatments
of 7.9 (control),
7.7 (reduced)
or 7.5 (extreme).
After jelly coat formation,
the researchers conducted
a series of measurements
to determine if there were
any size differences
brought about by the
pH treatment differences.
Chart Below:
Control pH 8.0
(green shading)
and urchins resident
at the low pH vent site
(blue shading).
