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Starting on January 1, 2024, several changes were made to the Periphyton, seston, and phytoplankton collection () and the Periphyton, seston, and phytoplankton chemical properties () data products to improve data quality. Decisions to change these data products are congruent with the framework for NEON Observational Sampling Design Optimization. These changes affect data from all NEON aquatic sites.

Periphyton, seston, and phytoplankton collection (DP1.20166.001): Morphological identification of microalgae is difficult partly due to their small size and partly due to incomplete and dynamic taxonomic description and documentation in North America. To better harmonize taxonomic identifications among expert taxonomists and improve efficiency, the following measures have been implemented after discussion with NEON Technical Working Groups (TWGs), community surveys, the NEON Science, Technology & Education Advisory Committee (STEAC), and the U.S. National Science Foundation (NSF):

• Microalgae taxonomic analysis was suspended from 1/1/2021 to 12/31/2023 to allow for time spent in analyzing existing data and working with technical working groups. Field samples collected during this time period were prepared for archiving at Arizona State University without taxonomic analysis. Samples will be available for use upon request.
• Field samples collected after 1/1/2024 are composited by habitat type prior to taxonomic analysis. This method is similar to that used in the EPA National Rivers and Streams Assessment (NRSA).
• Taxonomic analysis of benthic composite samples is comprised of 600 valve counts for diatoms on permanent slides. Soft algae will not be analyzed, which follows EPA NRSA laboratory methods. Slides are archived at the NEON Biorepository.
• Taxonomic analysis of phytoplankton composite samples is comprised of a 300 cell count in a counting chamber to capture soft algae and diatoms at a higher taxonomic rank following EPA National Lakes Assessment (NLA) laboratory methods. Preserved samples are archived at the NEON Biorepository.
• A voucher and reference flora workflow will be implemented for all microalgae taxonomic analyses after a pilot study with an expert taxonomy lab.
• An additional filter is collected from each composite sample for future use in metabarcoding analysis. NEON will not perform this analysis, but will send filters directly to the NEON Biorepository for archiving.
• The following tables have been replaced starting with the new data format in 2024:
  • alg_biomass replaced by alg_biomassComp
  • alg_taxonomyProcessed replaced by alg_taxonomyProcessedComp
  • alg_taxonomyRaw replaced by alg_taxonomyRawComp

Periphyton, seston, and phytoplankton chemical properties (DP1.20163.001): To align with changes made in the Periphyton, seston, and phytoplankton collection data product, improve sample collection efficiency, and improve data quality, the following measures have been implemented after discussion with NEON Technical Working Groups:

• Field samples collected after 1/1/2024 are composited by habitat type prior to chemical analysis, resulting in 2 composite samples per site and date. Once per year, an analytical replicate is created resulting in 3 samples per site and date.
• The following tables have been replaced starting with the new data format in 2024:
  • alg_domainLabChemistry replaced by alg_domainLabChemistryComp
  • alg_algaeExternalLabDataPerSample replaced by alg_algaeDataPerSampleCompCNPS and alg_algaeDataPerSampleCompChl