EAGER: Exploration of the presence and ecological significance of viral pathogens in the dynamics of Daphnia, a major pelagic grazer

Cornell University, Ithaca NY

Investigators

Abstract

Little is known about the identity or ecological significance of viruses in freshwater ecosystems, despite well-known disease effects of viruses on plants and animals in other ecosystems. This EAGER project makes the prediction that viruses are a widespread and important component of the food web of lakes. The research will measure the diversity and abundance of viruses that infect the dominant consumers of algal production in lakes, the crustacean zooplankton. While much is understood about the factors regulating the abundance of zooplankton in lakes, viruses have been almost entirely invisible to the approaches used. It is only recently that techniques have been developed capable of identifying the DNA sequences of uncultivated viruses, and permitting identification of viruses that infect zooplankton. Because there are currently no described viruses of freshwater zooplankton, and because of the high cost of obtaining viral DNA sequences, sufficient background data do not exist to justify a wider study of zooplankton viruses. Thus, this research will break new ground by determining the identity, infection rate, and distribution of viruses infecting Daphnia, a dominant freshwater crustacean in lakes world-wide. The viral infection rate within host populations will be investigated seasonally in Oneida Lake, New York, where extensive data on Daphnia dynamics already exist. Data on viruses will be compared with birth and death rates of zooplankton to understand the role of viruses in seasonal changes of zooplankton abundance. The spatial distribution of viruses in Oneida Lake, and in other nearby lakes will also be examined. This project represents a new, interdisciplinary collaboration between a virologist and an aquatic ecologist. Newly discovered viral genes will be made freely available to the wider scientific community for comparison to studies conducted elsewhere, which will expand our knowledge of the ecological significance of viral diversity. This project will also involve several undergraduate students who will receive research training in field ecology and microbiology, including cutting-edge molecular biological techniques.