Lake Michigan is becoming more transparent and now has potentially damaging ultraviolet (UV) radiation penetrating to deeper depths of the lake–leading to differential changes in fish abundances. Only fish that have innate mechanisms of protection will be able to mitigate damage from exposure to UV radiation. One way species can reduce damage from UV radiation is by having photoprotective pigmentation (PPP, Williamson et al. 2001). Photoprotective pigmentation provides protection from damaging UV radiation and includes substances such as melanin, carotenoids and mycosporine-like amino acids. They are common in many aquatic organisms, however the methods for quantifying pigmentation are not well-developed. Furthermore, previous methods for quantifying the presence of PPP in aquatic organisms required sacrificing a subset of individuals immediately after the experiment–making it difficult to track changes in pigmentation within the same organism. The goal of this study was to develop methodology that would quantify the development of PPP in larval fish, specifically those exposed to UV radiation. The methodology developed was modified from Siegenthaler et al. (2017) using open-source ImageJ software to quantify the pigment of native Cisco (Coregonus artedi) larvae collected from the Great Lakes. These methods were developed using the egg stage and tested with the larval stage. Using these new methods, we were able to track significant changes in pigmentation in larval fish after 24 hours of UV radiation exposure. The development of this methodology is a key component of a larger research project aimed at understanding the impact of UV on whitefish. By understanding the role of PPP in protecting fish at different life history stages, lake managers can develop strategies to protect these economically valuable fisheries. Additionally, using an open-source software product like ImageJ to expand existing techniques ensures accessibility to new methods by other researchers. Developing a new method of analysis requires a strong knowledge of the research question and context in which it will be used, skills that are essential for all scientists.
Author: Lauren Lynch
Faculty Advisors: Craig Williamson and Erin Overholt, Department of Biology
Graduate Student Advisor: Nicole Berry, Department of Biology
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