Our lab is working in collaboration with Tara Blackman, who initiated this research project, to understand how the changed geography and biology of Spirit Lake influenced the life history of rainbow trout as they recolonized the lake and its tributaries. To answer this, we are using information stored in the chemistry and daily growth rings of the ear bones (called otoliths) of rainbow trout. 

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In the aftermath of the 1980 eruption of Mount St. Helens the entire lake and its surroundings were reset biologically. During the eruption all the water in the lake was removed and heated before eventually flowing back into the lake. New, fluctuating, and often unstable watersheds were formed in the pumice plain left by the eruption. Over time the surrounding landscape progressed from nearly devoid of life through various stages of colonization and ecological succession, a natural experiment that was heavily studied by ecologists. During that time rainbow trout were reintroduced to the lake and quickly began exhibiting unusual life histories. 

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Rainbow trout in the lake began growing extremely quickly to very large sizes but dying at very young ages. Meanwhile juveniles in the surrounding creeks showed extremely skewed sex ratios. At the same time, the geography of damage from the eruption created a natural experiment, with some spawning streams in brand new watersheds on the pumice plain and others in areas with more stable, though still heavily affected watersheds. We hope that by studying the growth and chemical histories stored in the otoliths of fish in Spirit Lake we can uncover how ecological succession of the surrounding landscape affected the life-history of the trout, uncovering a deeper understanding of ecological succession and life-history theory in the process. 

Otoliths are goldmines of information. They are hard calcium carbonate structures located directly behind the brain in the inner ear of all bony fish. They function similarly to human ear bones, working as sensory organs that allow fish to hear sound, balance, orient themselves, and detect vibrations in the water. Otoliths grow continuously over the life of the fish, with new deposits being made every single day. These deposits leave behind a ring-like structure similar to tree rings that our lab analyzes to help solve the mystery of the rainbow trout.