Ocean acidification alters morphology of all otolith types in Clark’s anemonefish (Amphiprion clarkii)
- Published
- Accepted
- Subject Areas
- Aquaculture, Fisheries and Fish Science, Marine Biology, Climate Change Biology
- Keywords
- Ocean Acidification, Fish Otoliths, CaCO3 Mineralogy, Scanning Electron Microscopy
- Copyright
- © 2018 Holmberg et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Ocean acidification alters morphology of all otolith types in Clark’s anemonefish (Amphiprion clarkii) PeerJ Preprints 6:e27040v1 https://doi.org/10.7287/peerj.preprints.27040v1
Abstract
Ocean acidification, the ongoing decline of surface ocean pH and [CO32-] due to absorption of surplus atmospheric CO2, has far-reaching consequences for marine biota, especially calcifiers. Among these are teleost fishes, which internally calcify otoliths, critical elements of the inner ear and vestibular system. There is evidence in the literature that ocean acidification increases otolith size and alters shape, perhaps impacting otic mechanics and thus sensory perception. However, existing analyses of otolith morphological responses to ocean acidification are limited to 2-dimensional morphometrics and shape analysis. Here, we reared larval Clark’s anemonefish, Amphiprion clarkii (Bennett, 1830), in various seawater pH treatments analogous to future ocean scenarios in a 3x-replicated experimental design. Upon settlement, we removed all otoliths from each individual fish and analyzed them for treatment effects on morphometrics including area, perimeter, and circularity; further, we used scanning electron microscopy to screen otoliths visually for evidence of treatment effects on lateral development, surface roughness, and vaterite replacement. Our results corroborate those of other experiments with other taxa that observed otolith growth with elevated pCO2, and provide evidence that lateral development and surface roughness increased as well; we observed at least one of these effects in all otolith types. Finally, we review previous work investigating ocean acidification impacts on otolith morphology and hypotheses concerning function, placing our observations in context. These impacts may have consequences teleost fitness in the near-future ocean.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Tank Means for Statistical Analysis
Includes SL (mm); Area/SL, Perimeter/SL (um/mm); circularity (dimensionless); lateral development (scale of 1-5); percent visible crystals (scale of 5-50%); as well as tank counts of stocking density, settled, unsettled, dead (mort), and surviving (remaining) fish at the end of the experimental trial.
Statistical Analyses
Annotated R code used to run statistical analyses on fish and otolith morphometric data.
Micrograph Scoring Rubric
Rubric used for training and guiding scanning electron micrograph readers through scoring of four otolith mineralogical metrics. NOTE: “Core development” in the rubric has been renamed “lateral development” in the manuscript. In the rubric, “core” refers not to the otolith’s core but to the center of its lateral face.