title: In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.
abstract: Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO2and ambient pCO2coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH(T)= 7.89-7.92), larvae developing in elevated pCO2vent conditions (pH(T)= 7.50-7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response.
authors.affiliation: Department of Marine Science, University of Otago, Dunedin 9016, New Zealand miles.lamare@otago.ac.nz.
authors.forename: Miles D
authors.identifier: 0000-0001-8656-7240
authors.initials: MD
authors.lastname: Lamare
authors.affiliation: Department of Marine Science, University of Otago, Dunedin 9016, New Zealand.|Australia Institute of Marine Sciences, Townsville, 4810, Queensland, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Liddy
authors.affiliation: Australia Institute of Marine Sciences, Townsville, 4810, Queensland, Australia.
authors.forename: Sven
authors.initials: S
authors.lastname: Uthicke
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D060086:Hydrothermal Vents / Q000737:chemistry*; D007814:Larva / Q000502:physiology; D009792:Oceans and Seas; D010219:Papua New Guinea; D012617:Sea Urchins / Q000502:physiology*; D012623:Seawater / Q000737:chemistry*
chemical_list: D002245:Carbon Dioxide
keywords: CO2 vents; development; ocean acidification; sea urchin