Resources and Practices to Improve Diatom Data Quality

Abstract

Environmental programs in the UnitedStates face technical challenges that inhibit the ability to use diatoms in water quality monitoring and assessment projects. Specifically, inconsistent taxonomy can obscure diatom responses to environmental variables. Problems are the result of (1) limited access to a common set of taxonomic references, especially those that are geographically relevant, (2) inefficient enumeration protocols, (3) lack of complete and transparent documentation of taxa, and (4) limited opportunities for continued education, training, and knowledge sharing. However, robust resources and practices are available to improve diatom data quality and interpretation. Several resources improve diatom data quality, including a publicly accessible taxonomic reference (diatoms.org) and recommended practices. These practices include adoption of the voucher floras, random sample assignment, replicate microscope slides, and improved quality control. Finally, the Society for Freshwater Science Diatom Taxonomic Certification Committee is developing educational materials and certification exams to support practitioner training and to increase the diatom research knowledge base. The resources and practices in this article are broadly applicable to improving basic and applied research on diatoms worldwide.

Genus-level, trait-based multimetric diatom indices for assessing the ecological condition of rivers and streams across the conterminous United States

“…This idea is supported in studies of other assemblages; Leitão et al (2016) , for example, reported that rare taxa in stream fish assemblages were generally more sensitive to anthropogenic influences than those common enough to be included in impact assessments. The use of a trait-based approach, where all the taxa are assigned to traits, could be an advantage in countries like the U.S. where around a quarter of all species in North America are still without scientific names ( Potapova and Charles, 2003 ), many of which are restricted to a particular geographical region ( Alers-García et al, 2021 ). Given that the response of diatom traits is thought to be independent of ecoregions, and, hence, trait-based indices may be transferable among ecoregions with very different diatom flora ( Soininen et al, 2016 ), our traits metrics could potentially be applied to diatoms within any ecoregion, including those undescribed taxa with restricted distributions.…”

“…More specifically, whether it is necessary to use data with species-level resolution to achieve the regulatory goals for managing waters or could genus-level resolution suffice. Also, whether a species resolution is even feasible, especially when many species remain undescribed, and additional effort to document (i.e., images in voucher flora) taxa that do not fit current morphological species concepts is needed to maintain consistent taxonomy among different projects or within multi-year projects ( Alers-García et al, 2021 ).…”

“…In the U.S., the lack of taxonomic consistency is mostly attributed to four analytical practices ( Alers-García et al, 2021 ): (1) Many North American references are incomplete, prompting analysts to rely on a more comprehensive set of European references to assign names to North American species ( Kociolek and Spaulding, 2000 ). While many diatom species are shared between North America and Europe, many others are not shared, and in such cases, the use of European floras can result in the misapplication of names to North American taxa.…”

A Voucher Flora of Diatoms from Fens in the Tanana River Floodplain, Alaska

“…Observations: (Plate 5, Figs. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] The valves are 22.1-42.8 µm long and 5.4-6.5 µm wide, and stria density is 8-11 in 10 µm. The valve outline is lunate with a flat to slightly tumid ventral margin, moderately arched dorsal margin, and rounded apices.…”

Characterization of algal community composition and structure from the nearshore environment, Lake Tahoe (United States)

“…In the context of a project with support from the California Lahontan Water Quality Control Board that serves to examine factors effecting nuisance algal growth in the nearshore, a diatom voucher flora was constructed to serve as the taxonomic identification resource for the west shore of Lake Tahoe. Voucher floras, as discussed by Bishop et al (2017) and Alers-García et al (2021), serve as working laboratory documents that can provide taxonomic consistency and quality control for algal enumeration during a project lifetime. They are devised as in-house taxonomic references for a specific project that provides a consistent method for analyzing large sample sets that often employ multiple analysts (Tyree et al, 2020a), and may be conducted over an extended period of years.…”