Coccolithophore distribution in the Mediterranean Sea during spring 2011 (M84/3 cruise)


The Mediterranean Sea is considered a "hot spot" for climate change, being characterized by oligotrophic to ultra-oligotrophic waters and rapidly increasing seasurface temperature and changing carbonate chemistry. Coccolithophores are considered a dominant phytoplankton group in these waters. As marine calcifying organisms they are expected to respond to the ongoing changes in seawater carbonate chemistry. We provide here a description of the springtime coccolithophore distribution in the Mediterranean Sea and relate this to a broad set of in situ-measured environmental variables. Samples were taken during the R/V Meteor (M84/3) oceanographic cruise in April 2011, between 0 and 100 m water depth from 28 stations. Total diatom and silicoflagellate cell concentrations are also presented. Our results highlight the importance of seawater carbonate chemistry, especially [CO3]2- but also [PO4]3- in unraveling the distribution of heterococcolithophores, the most abundant coccolithophore life phase. Holo- and heterococcolithophores respond differently to environmental factors. For instance, changes in heterococcolithophore assemblages were best linked to the combination of [CO3]2-, pH, and salinity (rho = 0.57), although salinity might be not functionally related to coccolithophore assemblage distribution. Holococcolithophores, on the other hand, showed higher abundances and species diversity in oligotrophic areas (best fit, rho = 0.32 for nutrients), thriving in nutrient-depleted waters. Clustering of heterococcolithophores revealed three groups of species sharing more than 65% similarities. These clusters could be assigned to the eastern and western basins and deeper layers (below 50 m), respectively. In addition, the species Gephyrocapsa oceanica, G. muellerae, and Emiliania huxleyi morphotype B/C are spatially distributed together and trace the influx of Atlantic waters into the Mediterranean Sea. The results of the present work emphasize the importance of considering holo- and heterococcolithophores separately when analyzing changes in species assemblages and diversity. Our findings suggest that coccolithophores are a main phytoplankton group in the entire Mediterranean Sea and can dominate over siliceous phytoplankton. They have life stages that are expected to respond differently to the variability in seawater carbonate chemistry and nutrient concentrations.

Cell abundance in cell/l.

Supplement to: Oviedo, Angela Maria; Ziveri, Patrizia; Álvarez, Marta; Tanhua, Toste (2015): Is coccolithophore distribution in the Mediterranean Sea related to seawater carbonate chemistry? Ocean Science, 11(1), 13-32

Related Identifier
Metadata Access
Creator Oviedo, Angela Maria ORCID logo; Ziveri, Patrizia ORCID logo; Álvarez, Marta ORCID logo; Tanhua, Toste ORCID logo
Publisher PANGAEA
Publication Year 2017
Funding Reference Seventh Framework Programme Crossref Funder ID 265103 Mediterranean Sea Acidification in a Changing Climate
Rights Creative Commons Attribution 3.0 Unported;
OpenAccess true
Resource Type Supplementary Dataset; Dataset
Format text/tab-separated-values
Size 11340 data points
Discipline Earth System Research
Spatial Coverage (-5.751W, 33.580S, 35.172E, 41.250N); Aegean Sea; Eastern Basin; Ionian Sea; Adriatic Sea; Tirreno Sea; Western Basin; Alboran Sea; Strait of Gibraltar
Temporal Coverage Begin 2011-04-06T11:57:00Z
Temporal Coverage End 2012-04-08T22:57:00Z