Meeting Abstract
Fish that undergo ontogenetic migrations between habitats often encounter new light environments that require changes in the spectral sensitivity of the retina. For many fish, sensitivity of the retina changes to match the environmental spectrum, but the timing of retinal change relative to habitat shift remains unknown. Does retinal change in fish occur in anticipation of habitat shift, or is it a response to encountered changes in environmental light? Spectral sensitivity changes were examined over the development of the Atlantic tarpon (Megalops atlanticus) retina relative to ontogenetic shifts in habitat light. Spectral sensitivity of the retina was determined by electroretinography and compared to the spectral irradiance of habitats occupied by M. atlanticus from juveniles to adults. These data, along with previously known microspectrophotometric measurements of sensitivity in M. atlanticus, indicate retinal spectral sensitivity that matches the dominant wavelengths of environmental light for juvenile fish. For sub-adult M. atlanticus, however, spectral sensitivity does not match the dominant wavelength of light it occupies, but better matches the dominant wavelengths of light in the habitat of its forthcoming migration. These results indicate that the relationship between environmental light spectrum and spectral sensitivity of the retina changes during M. atlanticus development and suggest that such changes may be programmed to support visual anticipation of new photic environments.
