“Eggs of the Living Dead Meet America’s Most Polluted Lake”
Dr. Nelson G. Hairston Jr., Frank H.T. Rhodes Professor of Environmental Science, Department of Ecology and Evolutionary Biology at Cornell University, will lecture on Oct 24th on effects of pollution and cleanup efforts on ecosystems. Onondaga Lake in New York is reputed to be the most polluted lake in North America because of chemical industry and municipal wastes including phosphorus, salt, heavy metals, and PCBs. Pollution has changed over a century of inputs as industry shifts and environmental controls were implemented. The lake is now a superfund site and subsequent cleanup efforts have substantially improved its condition. Hairston and his colleagues have traced the effects of pollution on lake-ecosystem functioning by studying changes in the species of Daphnia present in the lake. Daphnia is a genus of microscopic crustacean that can produce diapausing eggs. These eggs have no detectable metabolism, thus they appear “dead” but they can still be hatched from some lakes after up to 300 years in the sediment. Diapausing eggs extracted from sediment cores of different ages can be hatched or analyzed genetically to reveal which species were present at a given time in history. By sequencing their nucleic acids (RNA and DNA), Dr. Hairston has uncovered an intriguing story of invasion by exotic pollution-tolerant Daphnia species as the native species disappeared followed by the return of native species as the pollution was cleaned up.