High-resolution ocean pH dynamics in four subtropical Atlantic benthic habitats
Other literature type
Hernández, C. A.
Hernández, J. C.
Oscillations of ocean pH are largely unknown in coastal environments and
ocean acidification studies often do not account for natural variability yet
most of what is known about marine species and populations is found out via
studies conducted in near shore environments. Most experiments designed to
make predictions about future climate change scenarios are carried out in
coastal environments with no research that takes into account the natural pH
variability. In order to fill this knowledge gap and to provide reliable
measures of pH oscillation, seawater pH was measured over time using moored
pH sensors in four contrasting phytocenoses typical of the north Atlantic
subtropical region. Each phytocenosis was characterized by its predominant
engineer species: (1) <i>Cystoseira abies-marina</i>, (2) a mix of gelidiales and geniculate corallines, (3)
<i>Lobophora variegata</i>, and (4) encrusting corallines. The autonomous pH measuring systems consisted
of a pH sensor; a data logger and a battery encased in a waterproof
container and allowed the acquisition of high-resolution continuous pH data
at each of the study sites. The pH variation observed ranged by between 0.09
and 0.24 pH<sub>NBS</sub> units. A clear daily variation in seawater pH was
detected at all the studied sites (0.04–0.12 pH<sub>NBS</sub> units).
Significant differences in daily pH oscillations were also observed between
phytocenoses, which shows that macroalgal communities influence the seawater
pH in benthic habitats. Natural oscillations in pH must be taken into
account in future ocean acidification studies to put findings in perspective
and for any ecological recommendations to be realistic.