Publication Date:
2022-10-24
Description:
Rhodolith beds built by free-living coralline algae are important ecosystems for marine biodiversity
and carbonate production. Yet, our mechanistic understanding regarding rhodolith physiology
and its drivers is still limited. Using three rhodolith species with different branching morphologies,
we investigated the role of morphology in species’ physiology and the implications for their
susceptibility to ocean acidification (OA). For this, we determined the effects of thallus topography
on diffusive boundary layer (DBL) thickness, the associated microscale oxygen and pH dynamics and
their relationship with species’ metabolic and light and dark calcification rates, as well as species’
responses to short-term OA exposure. Our results show that rhodolith branching creates low-flow
microenvironments that exhibit increasing DBL thickness with increasing branch length. This,
together with species’ metabolic rates, determined the light-dependent pH dynamics at the algal
surface, which in turn dictated species’ calcification rates. While these differences did not translate in
species-specific responses to short-term OA exposure, the differences in the magnitude of diurnal pH
fluctuations (~ 0.1–1.2 pH units) between species suggest potential differences in phenotypic plasticity
to OA that may result in different susceptibilities to long-term OA exposure, supporting the general
view that species’ ecomechanical characteristics must be considered for predicting OA responses.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
peerRev
Format:
application/pdf
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