Publication Date:
2015-01-16
Description:
Among bivalves, scallops are exceptional
due to their capacity to escape from predators by swimming
which is provided by rapid and strong claps that
are produced by the phasic muscle interspersed with
tonic muscle contractions. Based on the concept of oxygen
and capacity-limited thermal tolerance, the following
hypothesis was tested: ocean warming and acidification
(OWA) would induce disturbances in aerobic metabolic
scope and extracellular acid-case status and impair swimming
performance in temperate scallops. Following longterm
incubation under near-future OWA scenarios [20
vs. 10 °C (control) and 0.112 kPa CO2 (hypercapnia) vs.
0.040 kPa CO2 (normocapnic control)], the clapping performance
and metabolic rates (MR) were measured in
resting (RMR) and fatigued (maximum MR) king scallops,
Pecten maximus, from Roscoff, France. Exposure to
OA, either alone or combined with warming, left MR and
swimming parameters such as the total number of claps
and clapping forces virtually unchanged. Only the duration
of the escape response was affected by OA which
caused earlier exhaustion in hyper- than in normocapnic
scallops at 10 °C. While maximum MR was unaffected,
warm exposure increased RMR in both normocapnic and
hypercapnic P. maximus resulting in similar Q10 values of
~2.2. The increased costs of maintenance and the observation
of strongly reduced haemolymph PO2 levels indicate
that at 20 °C scallops have reached the upper thermal pejus
range with unbalanced capacities for aerobic energy metabolism.
As a consequence, warming to 20 °C decreased
mean phasic force during escape performance until fatigue.
The observed prolonged recovery time in warm incubated
scallops might be a consequence of elevated metabolic
costs at reduced oxygen availability in the warmth.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev
Format:
application/pdf
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