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Laurentian Great Lakes phytoplankton and their water quality characteristics, including a diatom-based model for paleoreconstruction of phosphorus.

Reavie ED, Heathcote AJ, Shaw Chraïbi VL - PLoS ONE (2014)

Bottom Line: 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.The diatom-based transfer function can be used in lake management when retrospective data are needed for tracking long-term degradation, remediation and trajectories.

View Article: PubMed Central - PubMed

Affiliation: Center for Water and the Environment, Natural Resources Research Institute, University of Minnesota Duluth, Duluth, Minnesota, United States of America.

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.

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Dominant diatom species (>5% relative abundance) for the eastern core of Lake Superior.A plot of corresponding DI-TP for the fossil assemblages is shown on the right. Black line indicates inferred TP and grey lines indicate the range of model error (RMSEP).
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pone-0104705-g005: Dominant diatom species (>5% relative abundance) for the eastern core of Lake Superior.A plot of corresponding DI-TP for the fossil assemblages is shown on the right. Black line indicates inferred TP and grey lines indicate the range of model error (RMSEP).

Mentions: Figure 5 presents the common diatom taxa (>5% in any sample) in a sediment core from eastern Lake Superior (unpublished data). The stratigraphy is based on relative diatom density, including the DI-TP results which indicate a temporary enrichment event. This inference was largely driven by a short-term abundance of A. islandica which temporarily replaces lower-nutrient Cyclotella and Discostella species through much of the 20th century. Passively plotting the Lake Superior fossil samples on the RDA traces the path of historical changes in the diatom assemblages (Figure 3). The long-term trend indicates a temporary movement of the scores in the direction of the TP vector from 1922 through 1970, a period that reflects nutrient enrichment in Lake Superior in association with the increased abundance of Aulacoseira islandica (unpublished data; [49]). Subsequent to 1970 the sample scores revert to locations close to pre-Euro-American samples, indicating TP reductions as the diatom assemblage shifted to a greater dominance by Cyclotella (unpublished data).


Laurentian Great Lakes phytoplankton and their water quality characteristics, including a diatom-based model for paleoreconstruction of phosphorus.

Reavie ED, Heathcote AJ, Shaw Chraïbi VL - PLoS ONE (2014)

Dominant diatom species (>5% relative abundance) for the eastern core of Lake Superior.A plot of corresponding DI-TP for the fossil assemblages is shown on the right. Black line indicates inferred TP and grey lines indicate the range of model error (RMSEP).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4126776&req=5

pone-0104705-g005: Dominant diatom species (>5% relative abundance) for the eastern core of Lake Superior.A plot of corresponding DI-TP for the fossil assemblages is shown on the right. Black line indicates inferred TP and grey lines indicate the range of model error (RMSEP).
Mentions: Figure 5 presents the common diatom taxa (>5% in any sample) in a sediment core from eastern Lake Superior (unpublished data). The stratigraphy is based on relative diatom density, including the DI-TP results which indicate a temporary enrichment event. This inference was largely driven by a short-term abundance of A. islandica which temporarily replaces lower-nutrient Cyclotella and Discostella species through much of the 20th century. Passively plotting the Lake Superior fossil samples on the RDA traces the path of historical changes in the diatom assemblages (Figure 3). The long-term trend indicates a temporary movement of the scores in the direction of the TP vector from 1922 through 1970, a period that reflects nutrient enrichment in Lake Superior in association with the increased abundance of Aulacoseira islandica (unpublished data; [49]). Subsequent to 1970 the sample scores revert to locations close to pre-Euro-American samples, indicating TP reductions as the diatom assemblage shifted to a greater dominance by Cyclotella (unpublished data).

Bottom Line: 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.The diatom-based transfer function can be used in lake management when retrospective data are needed for tracking long-term degradation, remediation and trajectories.

View Article: PubMed Central - PubMed

Affiliation: Center for Water and the Environment, Natural Resources Research Institute, University of Minnesota Duluth, Duluth, Minnesota, United States of America.

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.

Show MeSH
Related in: MedlinePlus