Data from: Rearing in strontium-enriched water induces vaterite otoliths in the Japanese rice fish, Oryzias latipes

Sagittal otoliths, typically composed of aragonite, are frequently laid
down rather as vaterite during growth in hatchery-reared fish populations.
Sagittal vateritisation is believed to impair individual hearing/balancing
abilities, but the causal mechanism remains unclear. Here we
experimentally demonstrated that rearing in Sr-rich water induces sagittal
vateritisation in the HdrR-II1 inbred strain of the Japanese rice
fish, Oryzias latipes. Both sagittae were partly vateritised in
70% of individuals subjected to the Sr2+ treatment (n = 10), whereas fish
reared in normal tap water showed no sagittal vateritisation (n = 8). Our
result is consistent with the theoretical prediction that vaterite becomes
thermodynamically more stable than aragonite as the Sr2+ concentration in
solution increases. A vateritic layer develops surrounding the original
aragonitic sagitta in vateritised otoliths, some of which take on a
comma-like shape. Electron probe microanalysis demonstrates that the
vateritised phase is characterised by lower Sr2+ and higher Mg2+
concentrations than the aragonitic phase. It is unlikely that increased
environmental Sr2+ is responsible for the sagittal vateritisation in
farmed fish. However, our findings likely help to establish an in vivo
assay using O. latipes to understand the physiological process underlying
the sagittal vateritisation in farmed fish.