Data from: Amelioration of ocean acidification and warming effects through physiological buffering of a macroalgae

Concurrent anthropogenic global climate change and ocean acidification is
expected to have a negative impact on calcifying marine organisms. While
knowledge of biological responses of organisms to oceanic stress has
emerged from single species experiments, these do not capture ecologically
relevant scenarios where the potential for multi-organism physiological
interactions is assessed. Marine algae provide an interesting case study,
as their photosynthetic activity elevates pH in the surrounding
microenvironment, potentially buffering more acidic conditions for
associated epiphytes. We present findings that indicate increased
tolerance of an important epiphytic foraminifera, Marginopora vertebralis,
to the effects of increased temperature (±3 °C) and pCO2 (~1000 µatm) when
associated with its common algal host, Laurencia intricata. Specimens of
M. vertebralis were incubated for 15 days in flow-through aquaria
simulating current and end-of-century temperature and pH conditions.
Physiological measures of growth (change in wet weight), calcification
(measured change in total alkalinity in closed bottles), photochemical
efficiency (Fv/Fm), total chlorophyll, photosynthesis (oxygen flux), and
respiration, were determined. When incubated in isolation, M. vertebralis
exhibited reduced growth in end-of-century projections of ocean
acidification conditions, while calcification rates were lowest in the
high-temperature, low-pH treatment. Interestingly, association with L.
intricata ameliorated these stress effects with the growth and
calcification rates of M. vertebralis being similar to those observed in
ambient conditions. Total chlorophyll levels in M. vertebralis decreased
when in association with L. intricata, while maximum photochemical
efficiency increased in ambient conditions. Net production estimates
remained similar between M. vertebralis in isolation and in association
with L. intricata, although both production and respiration rates of M.
vertebralis were significantly higher when associated with L. intricata.
These results indicate that the association with L. intricata increases
the resilience of M. vertebralis to stress, providing one of the first
examples of physiological buffering by a marine alga that can ameliorate
the negative effects of changing ocean conditions.