Venello, T.A., Calosi, P.,
Turner, L.M. and
Findlay, H.S.
2018
Overwintering individuals
of the Arctic krill
Thysanoessa inermis
appear tolerant to
short-term exposure
to low pH conditions.
Polar Biology 41:
341-352.
SUMMARY:
It appears this important
krill species will have
no problem maintaining
its key ecosystem role
under any of the ocean
acidification scenarios
projected for this region
of the ocean in the future.
Venello et al. report
"we found no significant
physiological impacts
of ocean acidification
on overwintering
individuals of T. inermis
from the Arctic fjord
of Kongsfjord." ...
"low pH does not
significantly affect
T. inermis' physiology
when considering
individuals' metabolic
rates and metabolite
concentrations."
Commenting on the
significance of their work,
the four researchers
say their results
"suggest that overwintering
individuals of T. inermis
may possess sufficient ability
to tolerate short-term
low pH conditions
due to their migratory
behavior, which exposes
T. inermis to the naturally
varying carbonate
chemistry observed
within Kongsfjord,
potentially allowing
T. inermis to tolerate
future ocean acidification
scenarios."
DETAILS:
Thysanoessa inermis,
one of the most abundant
krill species inhabiting
the northern waters
of the Atlantic Ocean,
play an important role
in the Arctic food web
by transferring energy
from phytoplankton
to higher trophic-level
species.
Venello et al. say
"understanding krill responses
to ocean acidification is essential
for predicting the future
of Arctic ecosystems."
They collected adult T. inermis
specimens from Kongsfjord,
located on the west coast
of Spitsbergen, Svalbard,
Norway, during the spring
month of April.
This particular krill species
overwinters in Kongsfjord,
and according to the authors
may therefore be
"particularly sensitive
to environmental changes,
as low food availability
[during overwintering]
may increase their sensitivity
to [ocean acidification] stress."
The krill were transported
to a laboratory where
they were acclimated
and then exposed to
four seawater pH treatments
for a period of seven days:
ambient (pH 7.96)
or reduced pH
(pH of 7.70, 7.65 or 7.28).
Measurements of
standard metabolic rate
(measured as oxygen
consumption) and energy
metabolism markers
(adenosine triphosphate
and L-lactate)
were conducted
at the end of the
experimental period
to estimate krill tolerance
under the three levels
of reduced seawater pH.