Effects of nitrogen on benthic diatom assemblages in high-elevation central and eastern alpine lakes
ABSTRACTWe explored patterns of benthic diatom composition across sixty-two high-elevation alpine lakes spanning a wide range of nitrogen (N) concentrations due to atmospheric deposition and background variation in lake and watershed characteristics. Our goals were to (1) assess the effect of lake w...
Published in: | Arctic, Antarctic, and Alpine Research |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Taylor & Francis Group
2023
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Subjects: | |
Online Access: | https://doi.org/10.1080/15230430.2023.2270821 https://doaj.org/article/5926d08af1c6464cb036a4593a34888b |
Summary: | ABSTRACTWe explored patterns of benthic diatom composition across sixty-two high-elevation alpine lakes spanning a wide range of nitrogen (N) concentrations due to atmospheric deposition and background variation in lake and watershed characteristics. Our goals were to (1) assess the effect of lake water N concentration on benthic diatom composition during late summer or fall conditions and (2) identify policy-relevant response thresholds. The analyses were carried out on a large set of diatom and water chemistry data, integrated with new data. Multivariate and correlation analyses revealed associations between pH, N concentration, and benthic diatom composition, but the effects of pH and N were confounded. However, partial correlation analysis allowed us to identify “N-responsive diatoms”; that is, diatom taxa with nonspurious associations with N. Focusing on these taxa, we detected a decline in the abundance of taxa preferring low N concentrations and an increase in the abundance of taxa preferring high N concentrations starting at NO3 concentrations of approximately 5 µmol L−1. We interpreted this shift as an effect of watershed N saturation due to atmospheric deposition. Based on the results, we suggest a late-summer or fall concentration threshold of 5 µmol NO3 L−1 to prevent change in benthic diatoms in high-elevation alpine lakes. |
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