Meeting Abstract
Upstream human disturbance can cause major changes in aquatic environments by increasing sedimentation in streams and rivers. This increase in turbidity is of growing concern, as important visual information available to aquatic organisms declines. Thus, for predators and prey that rely on sight, increasing turbidity is likely to be of great consequence. To investigate the effects of turbidity on predator-prey interactions, we reared Trinidadian guppies from birth through adulthood in clear or turbid water and measured the effects of these developmental treatments on guppies’ visual systems and behavioral responses to olfactory predator cues (i.e. kairomones). To assess treatment differences, we measured gene expression in guppy eyes using probe-based qPCR of nine opsin genes, one rhodopsin gene, and three housekeeping genes. We also measured anti-predator behaviors of guppies when exposed to predator kairomones. Anti-predator behavior was measured as the difference in activity before and after an olfactory predator cue was introduced into an individual’s assay tank. We found significant treatment effects on opsin expression, notably in mid-wave-sensitive and long-wave-sensitive opsins, which reflected changes in light absorbance in turbid water as measured with a spectrophotometer. We also found differences in prey behavior between treatments, suggesting that guppies may be compensating for lack of visual information in turbid environments by responding more to olfactory cues. Thus, guppies in turbid water are (1) restructuring the distribution of opsins in the retina and (2) adjusting behavioral responses to olfactory predator stimuli when visual information is poor. These results highlight the critical nature of developmental plasticity and behavior as means through which organisms cope with novel, human-altered environments.
