Differences in lens optical plasticity in two gadoid fishes meeting in the Arctic.

Mikael Jönsson, Oystein Varpe, Tomasz Kozlowski, Jørgen Berge, Ronald Kröger

Research output: Contribution to journalArticlepeer-review

10 Citations (SciVal)


Arctic and boreal/temperate species are likely to be evolutionary adapted to different light regimes. Currently, the boreal/temperate Atlantic cod (Gadus morhua) is coexisting with the native polar cod (Boreogadus saida) in the Arctic waters around Svalbard, Norway. Here, we studied light/dark adaptative optical plasticity of their eye lenses by exposing fish to bright light during the polar night. Schlieren photography, high-definition laser scanning and ray tracing were used to determine the optical properties of excised crystalline lenses. Both species have multifocal lenses, an optical adaptation for improved color vision. In polar cod, the optical properties of the lens were independent of light exposure. In the more southern Atlantic cod, the optical properties of the lens changed within hours upon exposure to light, even after months of darkness. Such fast optical adjustment has previously only been shown in a tropical cichlid. During the polar night the Atlantic cod lens seems to be unregulated and dysfunctional since it had an unsuitable focal length and severe spherical aberration. We present a system, to our knowledge unique, for studying visual plasticity on different timescales in relation to evolutionary history and present the first study on the polar cod visual system.
Original languageEnglish
Pages (from-to)949-957
JournalJournal of Comparative Physiology A
Issue number11
Publication statusPublished - 2014

Subject classification (UKÄ)

  • Zoology


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