title: Morphological plasticity in a calcifying modular organism: evidence from an in situ transplant experiment in a natural CO2 vent system.
abstract: Understanding is currently limited of the biological processes underlying the responses of modular organisms to climate change and the potential to adapt through morphological plasticity related to their modularity. Here, we investigate the effects of ocean acidification and seawater warming on the growth, life history and morphological plasticity in the modular bryozoan Calpensia nobilis using transplantation experiments in a shallow Mediterranean volcanic CO2 vents system that simulates pH values expected for the year 2100. Colonies exposed at vent sites grew at approximately half the rate of those from the control site. Between days 34 and 48 of the experiment, they reached a possible 'threshold', due to the combined effects of exposure time and pH. Temperature did not affect zooid length, but longer zooids with wider primary orifices occurred in low pH conditions close to the vents. Growth models describing colony development under different environmental scenarios suggest that stressed colonies of C. nobilis reallocate metabolic energy to the consolidation and strengthening of existing zooids. This is interpreted as a change in life-history strategy to support persistence under unfavourable environmental conditions. Changes in the skeletal morphology of zooids evident in C. nobilis during short-time (87 days) exposure experiments reveal morphological plasticity that may indicate a potential to adapt to the more acidic Mediterranean predicted for the future.
authors.affiliation: ENEA Marine Environment Research Centre , PO Box 224 , La Spezia 19100, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Lombardi
authors.affiliation: ENEA Marine Environment Research Centre , PO Box 224 , La Spezia 19100, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Cocito
authors.affiliation: Laboratory of Functional and Evolutionary Ecology , Stazione Zoologica Anton Dohrn , Villa Comunale, Naples 80077, Italy.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Gambi
authors.affiliation: Department of Earth Sciences , Natural History Museum , Cromwell Road, London SW7 5BD, UK.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Taylor
keywords: bryozoan; modularity; morphological plasticity; ocean acidification; seawater temperature; vent system