Walden Pond, Massachusetts 1800 Year Diatom and Chrysophyte Data Stager, J.C.; Wiltse, B.; Hubeny, J.B.; Yankowsky, E.; Nardelli, D.; Primack, R. Stager, J.C. Wiltse, B. Hubeny, J.B. Yankowsky, E. Nardelli, D. Primack, R. earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,Miscellaneous Pennales) earth science/paleoclimate/paleolimnology (organism index,null,null,percent,null,paleolimnology,null,microscopy,N,Ratio of chrysophyte cysts to diatoms) earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,Tabellaria flocculosa IIIP) earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,Asterionella ralfsii) earth science/paleoclimate/paleolimnology (age,null,null,year Common Era,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,Cyclotella bodanica) earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,Discostella stelligera) earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,Asterionella formosa) earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,Synedra nanana) earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,total Eunotia) earth science/paleoclimate/paleolimnology (identified diatom,null,null,percent,null,paleolimnology,null,microscopy,N,Achnanthidium minutissimum) earth science/paleoclimate/paleolimnology (organism index,null,null,percent,null,paleolimnology,null,microscopy,N,Ratio of chrysophyte scales to diatoms) earth science/paleoclimate/paleolimnology (organic matter,sediment,null,percent,null,paleolimnology,null,loss on ignition,N,null) earth science/paleoclimate/paleolimnology (total planktic diatoms,null,null,percent,null,paleolimnology,null,microscopy,N,null) earth science/paleoclimate/paleolimnology (Walden Pond>LATITUDE 42.439>LONGITUDE -71.339) Recent shifts in the ecological condition of Walden Pond, MA, are of potentially wide interest due to the lake's importance as a cultural, historical, and recreational resource in addition to its scientific value as an indicator of local and global environmental change. Algal microfossils in six sediment cores document changes in hydroclimate and trophic status of the lake during the last 1800 years and extend two previous sediment core records of shorter length. Low percentages of planktonic diatoms in the longest cores (WAL-3, WAL-15) indicate shallowing and/or greater water clarity associated with a relatively arid interval during the Medieval Climate Anomaly, ca. A.D. 1150-1300. Cultural eutrophication of the lake since the A.D. 1920s caused diatoms in the genera Asterionella and Synedra to increase in relative abundance at the expense of Cyclotella, Discostella, and the chrysophyte alga Mallomonas allorgei. Percentages of Asterionella and Synedra have remained fairly stable since A.D. 2000 when a previous sediment core study was conducted, but scaled chrysophytes have become more numerous. These findings suggest that, although mitigation efforts have curtailed anthropogenic nutrient inputs to Walden Pond, the lake has not returned to the pre-impact condition described by Henry David Thoreau and may become increasingly vulnerable to further changes in water quality in a warmer and possibly wetter future. STUDY NOTES: Diatom and chrysophyte records from Walden Pond core WAL-3, indicating hydroclimate and trophic changes during the last 1800 years. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Stager, J.C. Investigator : Wiltse, B. Investigator : Hubeny, J.B. Investigator : Yankowsky, E. Investigator : Nardelli, D. Investigator : Primack, R. 2018-01-14 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/23310 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/massachusetts/walden2018loi.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/massachusetts/walden2018diatom.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/massachusetts/walden2018loi.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/massachusetts/walden2018diatom.txt English https://www.ncdc.noaa.gov/paleo/study/23310 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/massachusetts/walden2018loi.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/massachusetts/walden2018diatom.txt Stager, J. Curt; Wiltse, Brendan; Hubeny, J. Bradford; Yankowsky, Eric; Nardelli, David; Primack, Richard2018Climate variability and cultural eutrophication at Walden Pond (Massachusetts, USA) during the last 1800 yearsPLoS ONE START YEAR: 499 AD * END YEAR: 2015 AD -71.339 42.439 -71.339 42.439