Meta-Analysis of Ocean Acidification Experiments on the Early Life-Stages of Marine Fishes

The effects of CO₂-induced ocean acidification (OA) on marine fish early life-stages (ELS) have received increased attention because the ELS are ecologically important and least likely to be resilient to changing ocean chemistry.  A small but growing number of studies have experimentally examined these effects.  Using a subset of these studies which met acceptance criteria (15 publications, 60 experiments), we assessed patterns that could be extracted from the resulting set of taxa, experimental protocols, and response variables.  Four primary ELS responses were evaluated:  survival, length, mass, and otolith area of larvae.  We examined broad responses to OA, then tested four hypotheses of no differences in OA-related outcomes due to:  H₁: phylogeny (orders); H₂: latitudinally defined biomes (temperate vs. tropical); H₃: egg habitats (demersal vs. pelagic); and H₄: duration of CO₂-exposure (embryonic and larval stages vs. the larvae stage).  The overall meta-analysis showed survival to decrease and otolith area to increase with OA.  Survival also varied between 1) taxa, 2) egg habitats, and 3) duration of experimental exposure.  The increased otolith area at higher CO₂ levels occurred across multiple taxa.  Biases in these data reflect a limited taxonomic diversity of study subjects to date.  Suggestions for OA reporting will be summarized.