Effects of glacier meltwater on the algal sedimentary record of an alpine lake in the central US Rocky Mountains throughout the late Holocene

TY - JOUR

T1 - Effects of glacier meltwater on the algal sedimentary record of an alpine lake in the central US Rocky Mountains throughout the late Holocene

AU - Slemmons, K.E.H.

AU - Saros, J.E.

AU - Stone, J.R.

AU - McGowan, S.

AU - Hess, C.T.

AU - Cahl, D.

N1 - CODEN: JOUPE Funding details: National Science Foundation, NSF Funding details: University of Maine Funding text 1: We thank Dennis Anderson, Andrea Nurse, and Clive Devoy for assistance with chemical analyses and pollen preparation at the University of Maine, and Teresa Needham and Graham Morris for assistance with pigment analyses at the University of Nottingham. Erin Overholt assisted with analysis of light data from Jasper and Albino. We are grateful for field and laboratory assistance provided by Carl Tugend, Carmen Daggett, Caleb Slemmons, Courtney Wigdahl, and Dom Winski. We thank Will Hobbs and Joy Ramstack Hobbs for assistance with the diatom statistical analysis. This project was funded by the US National Science Foundation (Division of Environmental Biology-0734277), as well as the Dan and Betty Churchill Fund and a University of Maine Correll Fellowship.

PY - 2015

Y1 - 2015

N2 - The effects of alpine glaciers on the hydrology, physical features, and biogeochemistry of lakes have been investigated over contemporary time scales. However, the influence of these factors on algal communities over longer time scales remains unclear, yet is critical to paleolimnological interpretation of environmental change in alpine regions. We examined sedimentary algal pigments and fossil diatom assemblages in two proximal lakes with equivalent local climates, one glacier-fed and one snow-fed, in the central Rocky Mountains (USA) to determine how glacier meltwater has altered algal records over the last 3,000 years. Differences between the records of the two lakes intensified during the Medieval Climate Anomaly and the Little Ice Age, with the glacier-fed lake exhibiting an overall increase in fossil algal pigment concentrations and greater diatom assemblage turnover. Starting 1,000 years ago, the glacier-fed lake in this study showed evidence of nitrogen enrichment from glacier meltwater, as indicated by increasing relative abundances of Asterionella formosa and, to a lesser extent, Fragilaria crotonensis. Since the Little Ice Age, diatom species richness declined in the glacier-fed lake, and further decreased following the 1950s, while assemblage turnover increased. These results demonstrate that glaciers can strongly alter the algal sedimentary record and should be considered when interpreting high-elevation lake records.

AB - The effects of alpine glaciers on the hydrology, physical features, and biogeochemistry of lakes have been investigated over contemporary time scales. However, the influence of these factors on algal communities over longer time scales remains unclear, yet is critical to paleolimnological interpretation of environmental change in alpine regions. We examined sedimentary algal pigments and fossil diatom assemblages in two proximal lakes with equivalent local climates, one glacier-fed and one snow-fed, in the central Rocky Mountains (USA) to determine how glacier meltwater has altered algal records over the last 3,000 years. Differences between the records of the two lakes intensified during the Medieval Climate Anomaly and the Little Ice Age, with the glacier-fed lake exhibiting an overall increase in fossil algal pigment concentrations and greater diatom assemblage turnover. Starting 1,000 years ago, the glacier-fed lake in this study showed evidence of nitrogen enrichment from glacier meltwater, as indicated by increasing relative abundances of Asterionella formosa and, to a lesser extent, Fragilaria crotonensis. Since the Little Ice Age, diatom species richness declined in the glacier-fed lake, and further decreased following the 1950s, while assemblage turnover increased. These results demonstrate that glaciers can strongly alter the algal sedimentary record and should be considered when interpreting high-elevation lake records.

KW - Climate

KW - Diatom fossil record

KW - Glacier meltwater

KW - Nitrogen

KW - Oligotrophic lakes

KW - Paleolimnological interpretation

U2 - 10.1007/s10933-015-9829-3

DO - 10.1007/s10933-015-9829-3

M3 - Article

SN - 0921-2728

VL - 53

SP - 385

EP - 399

JO - Journal of Paleolimnology

JF - Journal of Paleolimnology

IS - 4

ER -