Distribution and functional traits of polychaetes in a CO2 vent system: winners and losers among closely related species

• Main Authors: Gambi, Maria Cristina, Musco, Luigi, Giangrande, Adriana, Badalamenti, F, Micheli, Florenza, Kroeker, Kristy J
• Format: Dataset
• Language: English
• Published: PANGAEA 2016
• Subjects: Alkalinity; total; standard deviation; Aragonite saturation state; Behaviour; Benthos; Bicarbonate ion; Calcite saturation state; Calculated using seacarb; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; partial pressure; Category; CO2 vent; Coast and continental shelf; Community composition and diversity; Development; Entire community; Field observation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Individuals; Mediterranean Sea; Mortality/Survival; Number of taxa; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Potentiometric; Potentiometric titration; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.868889; https://doi.org/10.1594/PANGAEA.868889

We report on fine taxonomic and functional analyses of polychaetes associated with rocky reefs along a gradient of ocean acidification (OA) at the volcanic CO2 vent system off the Castello Aragonese (Ischia Island, Italy). Percent cover of algae and sessile invertebrates (a determinant of polychaete distribution) was classified into functional groups to disentangle the direct effects of low pH on polychaete abundance from the indirect effects of pH on habitat and other species associations. A total of 6459 polychaete specimens belonging to 83 taxa were collected. Polychaete species richness and abundance dramatically dropped under the extreme low pH conditions due to the disappearance of both calcifying and non-calcifying species. Differences in distribution patterns indicate that the decreasing pH modified the structure and biological traits of polychaete assemblages independent of changes in habitat. A detailed taxonomic analysis highlighted species-specific responses to OA, with closely related species having opposing responses to decreasing pH. This resulted in an increase in the abundance of filter feeders and herbivores with decreasing pH, while sessile polychaetes disappeared in the extreme low pH zones, and were replaced by discretely motile forms. Reproductive traits of the polychaete assemblages changed as well, with brooding species dominating the most acidified zones. The few taxa that were abundant in extreme low pH conditions showed high tolerance to OA (e.g. Amphiglena mediterranea, Syllis prolifera, Platynereis cf. dumerilii, Parafabricia mazzellae, Brifacia aragonensis), and are promising models for further studies on the responses of benthic organisms to the effects of reduced pH.