Monster Seminar Jam - Do you see what I see? Ontogenetic changes in the visual ecology of local marine fishes
Mr. Lyle Britt, Resource Assessment and Conservation Engineering division, AFSC
Fish occupy diverse habitats where light conditions range from the dim monochromatic waters of the deep ocean to the full spectral glare of nearshore tidepools and the highly tannic waters of small mountain streams. The aquatic environment varies in chromatic composition and absolute intensity making it a very dynamic milieu for organisms performing essential visual tasks. Fishes are truly impressive in their visual adaptations. One of the most common adaptations involves spectrally shifting the maximal sensitivity of the photoreceptor cells to match the prevailing background irradiance of their environment. This adaptive drive for spectrally tuning to the available light field shows that species from similar photic environments often have similar sensitivity to light of different wavelengths. While interspecific variation in spectral sensitivity does exist, it is typically thought to be a form of secondary tuning to meet behavioral drives within the confines of the available photic environment. But what about the case where different life stages of a species occupy different habitats and show different behaviors? Recent research has shown ontogenetic changes in spectral sensitivity can occur, allowing fish to retune throughout their development. However, the visual pigments we have observed in local marine fish larvae do not always appear to correlate with the prevailing background irradiance suggesting other factors may influence spectral tuning during the early life stages. While much effort has been dedicated to determining the spectral sensitivity of fishes, our knowledge of the ecological, environmental, or behavioral influences on spectral tuning are poorly understood. For instance, ultraviolet sensitivity has been correlated with planktivory by several researchers, but has been difficult to link conclusively in laboratory experiments. To begin to understand the significance and basis for spectral tuning during development, we examined the visual pigments of over 65 species of northeast Pacific marine fishes during their larval, juvenile, and adult life stages using a microspectrophotometer. The species examined were chosen to represent several different feeding modes, habitats, and phylogenies. Of the species examined, over 85% exhibited ontogenetic changes in spectral sensitivity, commonly associated with the onset of juvenile transformation from the larval stage. The results of this study suggest that behavior and feeding may play a greater role in spectral tuning during larval stages whereas the photic environment may influence spectral tuning during the later life stages.
Date and Time:
February 7, 2008,
11:00 am - 12:30 pm