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This dataset contains species richness data for epiphytic diatom communities collected from weir ponds in seven headwater streams within the Hubbard Brook Experimental Forest (HBEF) in New Hampshire between 2018 and 2021. Diatom samples were gathered using artificial bryophyte substrates, deployed in weir ponds to mimic natural diatom habitats. Species richness was quantified by identifying diatom taxa to the lowest possible taxonomic level, with 86 taxa spanning 43 genera recorded. This dataset represents the first comprehensive classification of diatom communities at HBEF, providing a baseline for future studies in this ecosystem. Environmental variables, including light availability, dissolved organic carbon, total dissolved nitrogen, and pH, were concurrently measured to assess their influence on diatom community composition. The light (lux) data used in this study is openly available in the EDI Data Portal at https://doi.org/10.6073/pasta/0f40b75b299494d736645d940fa2b5a4. The chlorophyll-a data and analysis methodology are available at https://doi.org/10.6073/pasta/7fa32d94240fc7780d62cb7e65eafdb2. Reach characteristics were sourced from the EDI Data Portal at https://doi.org/10.6073/pasta/3e4b95149245341d522383bba51de7c7. This study provides valuable insights into the relationships between environmental factors and diatom diversity in northern hardwood forest streams, aiding ecological monitoring and bioindicator studies. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. 

This dataset contains species abundance data of epilithic diatoms collected from the Upper Kuparuk River, Alaska (USA), spanning from 1997 to 2022. The dataset is part of a long-term study aimed at understanding the ecological impacts of phosphorus enrichment in Arctic freshwater ecosystems. Samples were collected annually from both phosphorus-fertilized and reference reaches of the river to assess the influence of nutrient enrichment on diatom community composition. The dataset includes detailed records of diatom species identified and their relative abundances in the phosphorus reach only. Analyses of this dataset using permutational multivariate analysis of variance (PERMANOVA) and Redundancy Analysis (RDA) revealed significant shifts in diatom communities attributable to phosphorus enrichment. Indicator Species Analysis identified key diatom species that are reliable indicators of phosphorus-enriched conditions. This dataset provides valuable insights into the long-term responses of diatom communities to nutrient enrichment and the ecological interactions with mosses that colonized the fertilized reach. It serves as an important resource for researchers studying nutrient dynamics, ecological monitoring, and the impacts of climate change on Arctic freshwater systems. 

This dataset contains species abundance data of epilithic diatoms collected from the Upper Kuparuk River, Alaska (USA), spanning from 1997 to 2022. The dataset is part of a long-term study aimed at understanding the ecological impacts of phosphorus enrichment in Arctic freshwater ecosystems. Samples were collected annually from the river to examine if physical, chemical, biological, weather, and climate variables influence diatom community composition over time. The dataset includes detailed records of diatom species identified and their relative abundances ins the reference reach only. Analyses of this dataset using permutational multivariate analysis of variance (PERMANOVA), canonical correspondence analysis (CCA), and partial canonical correspondence analysis (pCCA) . Analyses reveal significant shifts in diatom community composition over time, closely linked to changes in alkalinity, nitrate + nitrite, total dissolved phosphorus, dissolved organic carbon, and wind speed. We identify specific diatom taxa as bioindicators, highlighting their sensitivity to shifts in alkalinity, nitrate + nitrite, and wind speed. This dataset provides valuable insights on how climate change is reshaping the structure and function of Arctic rivers, underscoring the importance of diatoms as bioindicators in Arctic ecosystems. It serves as an important resource for researchers studying nutrient dynamics, ecological monitoring, and the impacts of climate change on Arctic freshwater systems.