A harmonized dataset of sediment diatoms from hundreds of lakes in the northeastern United States

Abstract

Sediment diatoms are widely used to track environmental histories of lakes and their watersheds, but merging datasets generated by different researchers for further large-scale studies is challenging because of taxonomic discrepancies caused by rapidly evolving diatom nomenclature and taxonomic concepts. We collated five datasets of lake sediment diatoms from the Northeastern USA using a harmonization process which included updating synonyms, tracking the identity of inconsistently identified taxa, and grouping those that could not be resolved taxonomically. Each harmonization step led to an increase in variation explained by environmental variables and a parallel reduction of variation attributable to taxonomic inconsistency. To maximize future use of the data and underlying specimens we provide the original and harmonized counts for 1327 core samples from 607 lakes, name translation schemes, sample metadata, specimen museum locations, and the Northeast Lakes Voucher Flora, which is a set of light microscope images grouped into 1154 morphological operational taxonomic units. Post-hoc harmonization enables data quality control when other approaches (e.g., upfront management of taxonomic consistency) are not possible.

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

“…Our use of a diatom voucher flora for the most speciose part of the algal assemblages provides a means of consistency between projects and research groups, providing it is adopted. Adopting a voucher flora approach earlier in assessment programs can prevent the need for resource intensive post-hoc harmonization, which may require re-analysis of slides and loss of species information when taxa cannot be reconciled (Potapova et al, 2022). Our voucher flora shows a 2-fold level of species diversity than was previously documented, most likely because of the methods involved in examining the diatom fraction through cleaned permanent mounts.…”

“…Species-level enumeration of periphyton, especially diatom taxa from lakes and rivers, is an important component of water quality monitoring. Documenting project-specific morphological species concepts enables harmonization with existing and future monitoring data, and is vital to maintain informative long-term records and maximize data use (Potapova et al, 2022). Given the high species diversity and degree of endemism in freshwater diatom communities, as well as rapid developments in freshwater diatom taxonomy, there are no single taxonomic references that may be satisfactorily employed for species-level identification.…”

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.…”

“…However, the labor-demanding and cost-prohibitive efforts to document individual specimens often prevent research teams from comprehensively designating representatives on slides (via circling individual diatom specimens) of all observed taxa in their samples [ 7 ]. When made accessible, documentation of project-specific morphological species boundaries (through digital images) can aid in taxonomic harmonization with current and future monitoring data, maximize data use, and maintain informative long-term records [ 8 ].…”

Cocconeis crisscrossis sp. nov., a new monoraphid diatom (Bacillariophyta) from southern China

“…Striae are usually uniseriate in freshwater species and the poroids are closed by hymenes ( Costa et al 2020 ). The frustule structure of Cocconeis is diverse and complex, species delineation requires detailed observations of the RV morphology, the SV and their connecting elements including valvocopulae and the cingulum ( Potapova and Spaulding 2013 ; Stancheva 2022 ).…”