US Long-Term Ecological Research Network

People in general, and ecologists in particular, are fascinated by species that show extreme fluctuations in abundance. This study investigates midges in Lake Myvatn, Iceland, and why their abundance fluctuates over 5 orders of magnitude in irregular cycles lasting 4-7 years. Juvenile midges feed on algae at the bottom of the lake, and 10-year-long experiments (encompassing a full peak-to-peak midge cycle) will test the hypothesis that the extreme midge fluctuations are caused when they consume all the algae. The research will also investigate the consequences of the midge cycles. During high midge years, over 300 metric tons of midges are deposited in the surrounding heathland, providing food for predators and nutrients (in the form of rotting carcasses) for plants. This provides a natural experiment to test hypotheses about how the lake and shoreline ecosystems are put together by observing how the pulses of midges ramify through the ecosystem networks.

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