REILLY, C.R.L.; Stanford University: Thermal noise limits visual sensitivity in the Rockfish (genus Sebastes).

An animal’s ability to behave appropriately in response to the dynamic events in its local environment depends on the ability of its sensory systems to detect and encode those events. This necessitates an informational relationship through which salient features of the local environment can be reliably encoded within the sensory periphery of the animal. Processes which limit the type or quality of information available to an animal will therefore constrain both behavior and ecology. I examined the effects of thermally induced noise on low-light visual sensitivity in congeneric species of a coastal marine fish (genus Sebastes) using the in-situ electroretinogram (ERG) to monitor threshold irradiance at environmentally realistic temperatures and photon fluxes. Visual threshold was significantly correlated with temperature (p<0.001) and threshold increased (sensitivity decreased) more than an order of magnitude with an increase of 10 degrees Celsius. The temperature dependence of sensitivity did not vary between species but absolute sensitivity did vary between species (ANCOVA, species as covariate, p<0.01). The species differences in absolute sensitivity correspond to the reported diel activity patterns of these animals. These data indicate that sensory noise may constrain organisms' informational niches.