Shared taxon assignments narrowed bounds on summer community change by 17% at seven Wisconsin lakes, 2002–2025

We tested whether incomplete taxon names permit a direction of change in summer community differences among seven Wisconsin lakes. We used NTL-LTER version 37.42 and 415 samples in 18 complete summers within 2002–2025. Shares exclude copepod nauplii. Fine units mostly combine source genus names; Bosminidae remains one family unit. Unresolved counts can receive any fine identity within their recorded broad group. A linear program uses the same lake assignment in all lake pairs. Mean distance had sharp bounds of 0.5369–0.6741 in 2002–2013 and 0.5047–0.6937 in 2014–2025. The later minus earlier range was −0.1694 to +0.1569. Shared assignments narrowed this range by 16.8% compared with separate pair minima. Both signs remained possible when assignments used only named units in the source. July–August and fixed monthly date checks retained both signs. These are bounds for fixed records under an assignment rule, not population confidence limits. They do not establish stable communities or species-level homogenization. The package has unchanged source data, provenance, code, all results, feasible assignments, primal and dual certificates, figures and offline repeat instructions.

zooplankton · taxonomic resolution · partial identification · total variation distance · linear programming · lake communities · reproducibility