title: Low pH conditions impair module capacity to regenerate in a calcified colonial invertebrate, the bryozoan Cryptosula pallasiana.
abstract: Many aquatic animals grow into colonies of repeated, genetically identical, modules (zooids). Zooid interconnections enable colonies to behave as integrated functional units, while plastic responses to environmental changes may affect individual zooids. Plasticity includes the variable partitioning of resources to sexual reproduction, colony growth and maintenance. Maintenance often involves regeneration, which is also a routine part of the life history in some organisms, such as bryozoans. Here we investigate changes in regenerative capacity in the encrusting bryozoan Cryptosula pallasiana when cultured at different seawater pCO2levels. The proportion of active zooids showing polypide regeneration was highest at current oceanic pH (8.1), but decreased progressively as pH declined below that value, reaching a six-fold reduction at pH 7.0. The zone of budding of new zooids at the colony periphery declined in size below pH 7.7. Under elevated pCO2conditions, already experienced sporadically in coastal areas, skeletal corrosion was accompanied by the proportional reallocation of resources from polypide regeneration in old zooids to the budding of new zooids at the edge of the colony. Thus, future ocean acidification can affect colonial organisms by changing how they allocate resources, with potentially profound impacts on life-history patterns and ecological interactions.
authors.affiliation: ENEA Marine Environment Research Centre, PO Box 224, 19100 La Spezia, Italy. Electronic address: chiara.lombardi@enea.it.
authors.forename: Chiara
authors.initials: C
authors.lastname: Lombardi
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
authors.affiliation: ENEA Marine Environment Research Centre, PO Box 224, 19100 La Spezia, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Cocito
authors.affiliation: Marine Biology and Ecology Research Centre, Plymouth University, Drake Circus, Plymouth, PL4 8AA, UK.
authors.forename: Camilla
authors.initials: C
authors.lastname: Bertolini
authors.affiliation: Marine Biology and Ecology Research Centre, Plymouth University, Drake Circus, Plymouth, PL4 8AA, UK; Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, 300 Allée des Ursulines, Rimouski, QC G5L 3A1, Canada.
authors.forename: Piero
authors.initials: P
authors.lastname: Calosi
mesh_terms: D000818:Animals; D002013:Bryozoa / Q000502:physiology*; D004784:Environmental Monitoring; D006863:Hydrogen-Ion Concentration; D007448:Invertebrates; D008018:Life Cycle Stages; D012623:Seawater / Q000737:chemistry*; D013312:Stress, Physiological
keywords: Bryozoa; Climate change; Modular organism; Ocean acidification; Phenotypic plasticity; Resource allocation