noaa-lake-23310 Walden Pond, Massachusetts 1800 Year Diatom and Chrysophyte Data Stager, J.C.; Wiltse, B.; Hubeny, J.B.; Yankowsky, E.; Nardelli, D.; Primack, R. Walden Pond, Massachusetts 1800 Year Diatom and Chrysophyte Data 2018-01-14 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/23310 Investigator J.C. Stager Investigator B. Wiltse Investigator J.B. Hubeny Investigator E. Yankowsky Investigator D. Nardelli Investigator R. Primack 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 population abundance geoscientificInformation 499 AD 2015 AD 1451 cal yr BP -65 cal yr BP Complete 42.439 42.439 -71.339 -71.339 47 47 Continent North America United States Of America Massachusetts Walden Pond>LATITUDE 42.439>LONGITUDE -71.339 None Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site. English DOC/NOAA/NESDIS/NCEI National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce https://www.ncdc.noaa.gov/data-access/paleoclimatology-data DATA Center Contact Bruce Bauer bruce.a.bauer@noaa.gov paleo@noaa.gov 303-497-6280 303-497-6513

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Boulder CO 80305-3328 USA online ASCII Stager, J. Curt; Wiltse, Brendan; Hubeny, J. Bradford; Yankowsky, Eric; Nardelli, David; Primack, Richard 2018 PLoS ONE

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.

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/massachusetts/walden2018loi.txt NOAA Template File; Walden Pond Organic Matter and Planktonic Diatom Percentage GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/massachusetts/walden2018diatom.txt NOAA Template File; Walden Pond Diatom Census Data USA/NOAA DIF Version 9.8.4 2018-12-11 2018-12-11