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National scale patterns of diatom-environment relationships in rivers and streams of the United States based on DNA metabarcoding
Citation:
Smucker, N., E. Pilgrim, R. Mitchell, A. Pollard, C. Nietch, J. Darling, AND D. Carlisle. National scale patterns of diatom-environment relationships in rivers and streams of the United States based on DNA metabarcoding. 36th Congress of the International Society of Limnology 2022, Berlin, GERMANY, August 07 - 22, 2022.
Impact/Purpose:
Diatoms have a long history of being used to characterize changes in environmental conditions and to identify effects of pollution in freshwater ecosystems. Recent advancements in DNA techniques and bioinformatics could help expand their use in monitoring and assessment programs by providing increasingly effective ways to quantify diatom diversity in environmental samples. This research summarizes nationwide DNA metabarcoding (rbcL) results for diatoms collected from 1859 streams and rivers during the summers of 2018 and 2019. Results can inform indicator development and applications of molecular tools to help manage environmental problems.
Description:
Diatoms have a long history of being used to characterize changes in environmental conditions and to identify effects of pollution in freshwater ecosystems. Recent advancements in DNA techniques and bioinformatics could help expand their use in monitoring and assessment programs by providing increasingly effective ways to quantify diatom diversity in environmental samples. Here, we present nationwide DNA metabarcoding (rbcL) results for diatoms collected from 1859 streams and rivers during the summers of 2018 and 2019. This survey was conducted for the United States Environmental Protection Agency’s National Rivers and Streams Assessment. Based on nonmetric multidimensional scaling (NMDS) results, changes in diatom assemblage structure were associated with two predominant environmental gradients. The first, representing the greatest change in assemblages, was associated with factors often associated with human activities, such as increased phosphorus and nitrogen concentrations, conductivity, turbidity, and increased benthic chlorophyll a. The second gradient was associated with pH and relative abundances of gene sequence reads for acidophilic taxa, which also were correlated with pH. Ecoregional patterns in the NMDS indicated streams in the Western Mountains and Northern Appalachians were associated with lower nutrient concentrations and conductivity, whereas streams in the Temperate, Northern, Southern, and Coastal Plains were associated with higher nutrient concentrations and conductivity. Streams in the Coastal Plains and in the Northern and Southern Appalachians were associated with lower pH. Ongoing work is focused on further examining regional differences and how these results could inform indicator development and applications of molecular tools to help manage environmental problems.
