Meeting Abstract
The marine light environment is highly variable in color and brightness due to ecological and anthropogenic variables such as depth, turbidity, and eutrophication. Recent studies indicate adaptive plasticity of the fish retina to light spectrum during development, but retinal plasticity to more transient changes in environmental light remains unknown. Here, we performed a study aimed at determining how light spectrum affects wavelength sensitivity and opsin gene expression in the Atlantic tarpon (Megalops atlanticus) on two- and four-month time scales. Sixteen juvenile tarpon were placed in either 590nm (red) or 420nm (blue) light conditions and retinal function was measured by electroretinography (ERG) and quantitative PCR (qPCR). At two months, tarpon of the red condition had a longer-wavelength peak sensitivity than fish in the blue condition. No significant change in wavelength sensitivity occurred between two and four months within each color condition. Relative expression of long-wavelength sensitive (LWS) and short-wavelength sensitive (SWS2) opsin genes across conditions was non-intuitive, with both genes having significantly higher expression levels in the blue condition. It appears by ERG that fish retina rapidly adjust color sensitivity to environmental spectra and only fine-tune sensitivity thereafter, and that these adjustments are governed by post-transcriptional regulation of the cone opsin genes or other processes undetectable by qPCR. The results suggest that fish have the ability to adjust wavelength sensitivity to environmental light spectra, making them resilient to disturbances in underwater light quality.
