Temperature as a likely driver shaping global patterns in mineralogical composition in bryozoans: Implications for marine calcifiers under Global Change

The Southern Ocean is showing one of the most rapid responses to
human-induced global change, thus acting as a sentinel of the effects on
marine species and ecosystems. Ocean warming and acidification are already
impacting benthic species with carbonate skeletons, but the magnitude of
these changes to species and ecosystems remains largely unknown. Here we
provide the largest carbonate mineralogical dataset to date for Southern
Ocean bryozoans, which are diverse, abundant and important as carbonate
producers, thus making them excellent for monitoring the effects of ocean
warming and acidification. To improve our understanding of how bryozoans
might respond to ocean warming and acidification, we assess latitudinal
and seafloor temperature patterns of skeletal mineralogy using bryozoan
species occurrences together with temperature data for the first time. Our
findings, combining new mineralogical data with published data from warmer
regions, show that the proportions of high-Mg calcite and bimineralic
species increase significantly towards lower latitudes and with increasing
seawater temperature. These patterns are consistent with the hypothesis
that seawater temperature is likely a significant driver of variations in
bryozoan mineralogy at a global scale.