title: Conspecific aggregations mitigate the effects of ocean acidification on calcification of the coralPocillopora verrucosa.
abstract: In densely populated communities, such as coral reefs, organisms can modify the physical and chemical environment for neighbouring individuals. We tested the hypothesis that colony density (12 colonies each placed ∼0.5 cm apart versus ∼8 cm apart) can modulate the physiological response (measured through rates of calcification, photosynthesis and respiration in the light and dark) of the coralPocillopora verrucosato partial pressure of CO2(PCO2) treatments (∼400 μatm and ∼1200 μatm) by altering the seawater flow regimes experienced by colonies placed in aggregations within a flume at a single flow speed. While light calcification decreased 20% under elevated versus ambientPCO2for colonies in low-density aggregations, light calcification of high-density aggregations increased 23% at elevated versus ambientPCO2As a result, densely aggregated corals maintained calcification rates over 24 h that were comparable to those maintained under ambientPCO2, despite a 45% decrease in dark calcification at elevated versus ambientPCO2Additionally, densely aggregated corals experienced reduced flow speeds and higher seawater retention times between colonies owing to the formation of eddies. These results support recent indications that neighbouring organisms, such as the conspecific coral colonies in the present example, can create small-scale refugia from the negative effects of ocean acidification.
authors.affiliation: Department of Biology, California State University, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA nicolas.r.evensen@gmail.com.|Marine Spatial Ecology Lab, Australian Research Council Centre of Excellence for Coral Reef Studies and School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
authors.forename: Nicolas R
authors.identifier: 0000-0003-3318-5593
authors.initials: NR
authors.lastname: Evensen
authors.affiliation: Department of Biology, California State University, 18111 Nordhoff Street, Northridge, CA 91330-8303, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Edmunds
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000254:growth & development*; D002113:Calcification, Physiologic; D002245:Carbon Dioxide / Q000378:metabolism*; D057894:Coral Reefs; D006863:Hydrogen-Ion Concentration; D010788:Photosynthesis; D012623:Seawater / Q000032:analysis
chemical_list: D002245:Carbon Dioxide
keywords: Coral growth; Facilitation; High PCO2; Hydrodynamics; Species interactions