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1. Species Abundance Counts of Benthic Diatoms in Response to Phosphorus Fertilization: Data from the Upper Kuparuk River Experiment (UKRE), Alaska, 1997-2022

   https://doi.org/10.18739/A2PG1HQ44  

   Sahlmann, Lindsey (January 2024, NSF Arctic Data Center)

   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. 

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2. Phytoplankton assemblage responses to nitrogen following COVID-19 stay–in–place orders in western Long Island Sound (New York/Connecticut)

   https://doi.org/10.1016/j.marenvres.2024.106371  

   Brown, Maximillian; Ambrosone, Mariapaola; Turner, Kyle J.; Humphries, Georgie E.; Tzortziou, Maria; Anglès, Sílvia; Panzeca, Caterina; Greenfield, Dianne I. (April 2024, Marine Environmental Research)

   This study evaluated water quality, nitrogen (N), and phytoplankton assemblage linkages along the western Long Island Sound (USA) shoreline (Nov. 2020 – Dec. 2021) following COVID-19 stay-in-place (SIP) orders through monthly surveys and N-addition bioassays. Ammonia-N (AmN; NH3+NH4+) negatively correlated with total chlorophyll-a (chl-a) at all sites; this was significant at Alley Creek, adjacent to urban wastewater inputs, and at Calf Pasture, by the Norwalk River (Spearman rank correlation, p<0.01 and 0.02). Diatoms were abundant throughout the study, though dinoflagellates (Heterocapsa, Prorocentrum), euglenoids/cryptophytes, and both nano- and picoplankton biomass increased during summer. In field and experimental assessments, high nitrite+nitrate (N+N) and low AmN increased diatom abundances while AmN was positively linked to cryptophyte concentrations. Likely N+N decreases with presumably minimal changes in AmN and organic N during COVID-19 SIP resulted in phytoplankton assemblage shifts (decreased diatoms, increased euglenoids/cryptophytes), highlighting the ecological impacts of N-form delivered by wastewater to urban estuaries. 

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3. North Temperate Lakes LTER: Chemical Limnology of Primary Study Lakes: Nutrients, pH and Carbon 1981 - current

   https://doi.org/10.6073/pasta/325232e6e4cd1ce04025fa5674f7b782  

   Magnuson, John J; Carpenter, Stephen R; Stanley, Emily H (January 2023, Environmental Data Initiative)

   Parameters characterizing the nutrient chemistry of the eleven primary lakes (Allequash, Big Muskellunge, Crystal, Sparkling, and Trout lakes, unnamed lakes 27-02 [Crystal Bog] and 12-15 [Trout Bog], Mendota, Monona, Wingra, and Fish) are measured at multiple depths throughout the year. These parameters include total nitrogen, total dissolved nitrogen, nitrite+nitrate-N, ammonium-N, total phosphorus, total dissolved phosphorus, dissolved reactive phosphorus (only in the southern lakes and not in Wingra and Fish after 2003), bicarbonate-reactive filtered and unfiltered silica (both discontinued in 2003), dissolved reactive silica, pH, air equilibrated pH (discontinued in 2014 in the northern lakes and in 2020 in the southern lakes), total alkalinity, total inorganic carbon, dissolved inorganic carbon, total organic carbon, dissolved organic carbon, and total particulate matter (only in the northern lakes in this data set; total particulate matter in southern lakes starting in 2000 is available in a separate dataset). Sampling Frequency: Northern lakes- monthly during ice-free season - every 5 weeks during ice-covered season. Southern lakes- Southern lakes samples are collected every 2-4 weeks during the summer stratified period, at least monthly during the fall, and typically only once during the winter, depending on ice conditions. Number of sites: 11 

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4. Dissolved Macronutrient Concentrations from Depth Profiles and Incubation Experiments from STING I Cruise AE2305 on R/V Atlantic Explorer in the Gulf of Mexico from February to March 2023

   https://doi.org/10.26008/1912/bco-dmo.929305.1  

   Buck, Kristen N; Parente, Caitlyn E; Caprara, Salvatore; Boiteau, Rene M; Chappell, Phoebe Dreux; Conway, Timothy M; Knapp, Angela N; Smith, Chris; Tamborski, Joseph; Parente, Caitlyn E (January 2024, Biological and Chemical Oceanography Data Management Office (BCO-DMO))

   Concentrations of inorganic dissolved macronutrients, including phosphate, nitrate plus nitrite (N+N), silicic acid, and nitrite, from phytoplankton shipboard incubation experiments and depth profiles collected on STING I cruise AE2305 on R/V Atlantic Explorer in the Gulf of Mexico from February to March 2023. This project investigates how groundwater discharge delivers important nutrients to the coastal ecosystems of the West Florida Shelf. Preliminary studies indicate that groundwater may supply both dissolved organic nitrogen (DON) and iron in this region. In coastal ecosystems like the West Florida Shelf that have very low nitrate and ammonium concentrations, DON is the main form of nitrogen available to organisms. Nitrogen cycling is strongly affected by iron availability because iron is essential for both photosynthesis and for nitrogen fixation. This study will investigate the sources and composition of DON and iron, and their influence on the coastal ecosystem. The team will sample offshore groundwater wells, river and estuarine waters, and conduct two expeditions across the West Florida Shelf in winter and summer. 

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5. Dissolved trace metal and macronutrient concentration data from incubation experiments conducted during the May 2021 EXPORTS North Atlantic cruise (DY131)

   https://doi.org/10.26008/1912/bco-dmo.947637.1  

   Buck, Kristen N; Navarro-Estrada, Delfina; Caprara, Salvatore; Brzezinski, Mark A; Jenkins, Bethany D; Navarro-Estrada, Delfina; Buck, Kristen N (January 2025, Biological and Chemical Oceanography Data Management Office (BCO-DMO))

   This dataset includes trace metal (iron, manganese, cobalt, nickel, copper, zinc, cadmium, lead) and macronutrient (nitrate&nitrite, nitrite, phosphate, silicic acid) concentration data from incubation experiments conducted on board the RRS Discovery during the EXPORTS North Atlantic campaign at the Porcupine Abyssal Plain-Sustained Observatory (PAP-SO) site (DY131). In these experiments, additions of macronutrients (N, P, Si) and Fe were used to assess the level of Si, N, and Fe stress being experienced by the phytoplankton and to contextualize taxa-specific metatranscriptome responses for resolving gene expression profiles in the in-situ communities. This research project focuses on the vertical export of the carbon associated with a major group of phytoplankton, the diatoms in the North Atlantic near the Porcupine Abyssal Plain. The major objective is to understand how diatom community composition and the prevailing nutrient conditions create taxonomic differences in metabolic state that combine to direct diatom taxa to different carbon export pathways. The focus is on diatoms, given their large contribution to global marine primary productivity and carbon export which translates into a significant contribution to the biogeochemical cycling of carbon (C), nitrogen (N), phosphorus (P), iron (Fe) and silicon (Si). It is hypothesized that the type and degree of diatom physiological stress are vital aspects of ecosystem state that drive export. To test this hypothesis, combined investigator expertise in phytoplankton physiology, genomics, and trace element chemistry is used to assess the rates of nutrient use and the genetic composition and response of diatom communities, with measurements of silicon and iron stress to evaluate stress as a predictor of the path of diatom carbon export. The EXPORTS field campaign in the North Atlantic sampled a retentive eddy over nearly a month in May 2021, which coincided with the decline of the North Atlantic Spring Bloom. 

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