title: Laurentian Great Lakes phytoplankton and their water quality characteristics, including a diatom-based model for paleoreconstruction of phosphorus.
abstract: Recent shifts in water quality and food web characteristics driven by anthropogenic impacts on the Laurentian Great Lakes warranted an examination of pelagic primary producers as tracers of environmental change. The distributions of the 263 common phytoplankton taxa were related to water quality variables to determine taxon-specific responses that may be useful in indicator models. A detailed checklist of taxa and their environmental optima are provided. Multivariate analyses indicated a strong relationship between total phosphorus (TP) and patterns in the diatom assemblages across the Great Lakes. Of the 118 common diatom taxa, 90 (76%) had a directional response along the TP gradient. We further evaluated a diatom-based transfer function for TP based on the weighted-average abundance of taxa, assuming unimodal distributions along the TP gradient. The r(2) between observed and inferred TP in the training dataset was 0.79. Substantial spatial and environmental autocorrelation within the training set of samples justified the need for further model validation. A randomization procedure indicated that the actual transfer function consistently performed better than functions based on reshuffled environmental data. Further, TP was minimally confounded by other environmental variables, as indicated by the relatively large amount of unique variance in the diatoms explained by TP. We demonstrated the effectiveness of the transfer function by hindcasting TP concentrations using fossil diatom assemblages in a Lake Superior sediment core. Passive, multivariate analysis of the fossil samples against the training set indicated that phosphorus was a strong determinant of historical diatom assemblages, verifying that the transfer function was suited to reconstruct past TP in Lake Superior. Collectively, these results showed that phytoplankton coefficients for water quality can be robust indicators of Great Lakes pelagic condition. The diatom-based transfer function can be used in lake management when retrospective data are needed for tracking long-term degradation, remediation and trajectories.
authors.affiliation: Center for Water and the Environment, Natural Resources Research Institute, University of Minnesota Duluth, Duluth, Minnesota, United States of America.
authors.forename: Euan D
authors.initials: ED
authors.lastname: Reavie
authors.affiliation: Groupe de Recherche Interuniversitaire en Limnologie, Département des Sciences Biologiques, Université du Québec à Montréal, Montréal, Québec, Canada.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Heathcote
authors.affiliation: Department of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America.
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Shaw Chraïbi
mesh_terms: D017377:Diatoms / Q000145:classification; D004784:Environmental Monitoring; D006114:Great Lakes Region; D060106:Lakes / Q000032:analysis*; D008954:Models, Biological; D010758:Phosphorus / Q000032:analysis*; D010839:Phytoplankton / Q000145:classification; D060753:Water Quality
chemical_list: D010758:Phosphorus
references.citation: Proc Natl Acad Sci U S A. 2013 Apr 16;110(16):6448-52
references.pmid: 23576718
references.citation: Environ Monit Assess. 1994 Jul;31(3):275-307
references.pmid: 24213968