Sierra Nevada Aquatic Research Laboratory

10 Jul, 11 AM - 31 Jul, 03 AM

Many fishes sequester ultraviolet (UV) absorbing compounds in the tissues of their eyes and in the mucus covering their skin. We have documented environmental, dietary and geographic correlates with the quality and quantity of these UV absorbing compounds, but many questions remain. We are interested in determining whether trout (most likely rainbow trout (Onchorhynchus mykiss), but we can work with those species most easily available) from lakes at different elevations differ in the kinds and quantities of these compounds. We plan to compare the expected changes in fish mucus among animals held in natural levels of solar radiation including and excluding the UV portion of the spectrum. We hope to include an additional factor in this experimental portion of the project by providing some animals with a diet free of the putative UV-blockers and some with a diet enriched with these compounds. For measuring the altitudinal effects, we plan to collect fishes from outside of the Reserve, albeit from nearby lakes and streams (e.g. Convict Lake, Valentine Lake and lakes higher in elevation depending on snow conditions). These fishes will be euthanized and samples of their ocular tissues (lens, humors and cornea) and their epithelial mucus will be assessed either in the field or upon return to SNARL facilities. Assessment of these tissues involves measuring the spectral absorbance of broad-spectrum light through the sample using a custom-configured microscope stand, a calibrated light source and a spectrophotometer. The experiment used to test effects of UV exposure and diet will most likely employ fishes obtained from a local hatchery and thus will entail holding animals from outside the Reserve in SNARL facilities. Depending on our success in obtaining funding, we hope to hold small groups of fish (6) under the following conditions: (a) UV present, enriched diet; (b) UV present, deficient diet; (c) UV absent, enriched diet; (d) UV absent, deficient diet. Holding facilities would be out-of-doors and exposed to natural solar radiation. These would be covered with UV transmitting acrylic (UV present) or UV blocking acrylic (UV absent). All fishes would be fed a nutritionally-complete, casein based diet. Those receiving the 'enriched diet' would have Acanthophor spicifera (an abundant marine alga high in mycosporine-like amino acids) added to the feed; the remaining fish would receive the same diet except that A. spicifera would not be added ('deficient diet'). Fishes would be monitored throughout the 14-18 day period for good health, and their mucus wouls be sampled at the start of the experiment and every 3-4 days thereafter. At the conclusion of the experiment, all fishes would be euthanized. Of course every effort would be made to prevent escape of these fish. For the experimental portion, fishes may be held in concrete tanks or in the stream channels. Depending on the configuration of the circulation system, some of the feed provided to our fishes is likely to leave the system downstream. We plan to make every effort to minimize this, and expect no significant impact on the downstream habitat due to the low quantities involved and the short duration. We certainly welcome any suggestions for further minimizing possible impacts.

Visit #2353 @Sierra Nevada Aquatic Research Laboratory

Approved

Under Project # 1880 | Research

Dietary and UV effects on trout eyes and mucus

research_scientist - University of California, San Diego

Reservation Members(s)

Group of 2 Other Jul 10 - 31, 2004 (22 days)
Group of 2 Research Scientist/Post Doc Jul 10 - 31, 2004 (22 days)
Peter Nelson Jul 10 - 31, 2004 (22 days)

Reserve Resources(s) | Create Invoice

Q1 5 Jul 10 - 31, 2004