AB - Vol. 20 No.1 - Feature article

Sectioned otolith of Atlantic croaker Micropogonias undulatus, showing laser transect (faint line above the yellow dashed line) from core (early life) to edge (experimental period). Scale bar = 850 µm. Photo: J. Mohan

Mohan J, Rahman MS, Thomas P, Walther B


Influence of constant and periodic experimental hypoxic stress on Atlantic croaker otolith chemistry


Mohan et al. conducted controlled experiments on Atlantic croaker to examine the response of otolith elemental ratios to either constant or periodic hypoxia exposure for one or two months. No difference in otolith chemistry was detected between hypoxic and normoxic treatments, though fish growth was reduced by constant hypoxia in both experiments. Periodic hypoxia did influence some otolith elements, but the magnitudes of responses were minimal compared to environmental variation driven by water chemistry. Given that otolith chemistry was minimally affected by stress alone, these results suggest that redox-sensitive elements in otoliths such as manganese could provide important insight into lifetime environmental hypoxia exposure histories for mobile fishes.


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