title: Coralline algae in a naturally acidified ecosystem persist by maintaining control of skeletal mineralogy and size.
abstract: To understand the effects of ocean acidification (OA) on marine calcifiers, the trade-offs among different sublethal responses within individual species and the emergent effects of these trade-offs must be determined in an ecosystem setting. Crustose coralline algae (CCA) provide a model to test the ecological consequences of such sublethal effects as they are important in ecosystem functioning, service provision, carbon cycling and use dissolved inorganic carbon to calcify and photosynthesize. Settlement tiles were placed in ambient pH, low pH and extremely low pH conditions for 14 months at a natural CO2vent. The size, magnesium (Mg) content and molecular-scale skeletal disorder of CCA patches were assessed at 3.5, 6.5 and 14 months from tile deployment. Despite reductions in their abundance in low pH, the largest CCA from ambient and low pH zones were of similar sizes and had similar Mg content and skeletal disorder. This suggests that the most resilient CCA in low pH did not trade-off skeletal structure to maintain growth. CCA that settled in the extremely low pH, however, were significantly smaller and exhibited altered skeletal mineralogy (high Mg calcite to gypsum (hydrated calcium sulfate)), although at present it is unclear if these mineralogical changes offered any fitness benefits in extreme low pH. This field assessment of biological effects of OA provides endpoint information needed to generate an ecosystem relevant understanding of calcifying system persistence.
authors.affiliation: School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK nick.kamenos@glasgow.ac.uk.
authors.forename: N A
authors.identifier: 0000-0003-3434-0807
authors.initials: NA
authors.lastname: Kamenos
authors.affiliation: School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: G
authors.initials: G
authors.lastname: Perna
authors.affiliation: Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Dohrn-Benthic Ecology Center, Villa Dohrn, Punta San Pietro 80077 Ischia, Naples, Italy.
authors.forename: M C
authors.initials: MC
authors.lastname: Gambi
authors.affiliation: Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950, USA.
authors.forename: F
authors.initials: F
authors.lastname: Micheli
authors.affiliation: Ecology and Evolutionary Biology, University of California Santa Cruz, CA 95064, USA.
authors.forename: K J
authors.initials: KJ
authors.lastname: Kroeker
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000382:microbiology*; D002119:Calcium Carbonate / Q000737:chemistry*; D017753:Ecosystem; D006863:Hydrogen-Ion Concentration; D058086:Microalgae / Q000472:pathogenicity*; D012623:Seawater / Q000737:chemistry*
chemical_list: D002119:Calcium Carbonate
keywords: crustose coralline algae; ecosystem; growth; mineralogy; ocean acidification; vents