Summer Daphnia density share rose at Big Muskellunge and fell at Trout Bog in 2014–2025 versus 2002–2013

We tested changes in summer Daphnia density share in seven northern Wisconsin lakes. We used NTL-LTER version 37.42 and 534 samples in 159 complete June–August lake-years. All selected years followed the 2001 preservation change. Each month, year and lake had equal weight at its averaging step. Mean share rose from 8.32% in 2002–2013 to 9.63% in 2014–2025. The change was +1.31 percentage points, with a nominal 95% shared three-year block interval of −0.29 to +2.84. Big Muskellunge rose by 7.42 points and Trout Bog fell by 7.19 points. Their approximate simultaneous seven-lake intervals excluded zero. These directions also held after changes in the denominator, season, date selection and year coverage. Crystal Bog rose by 7.60 points, but its uncertainty was more sensitive to the time and season rules. At Trout Bog, other crustacean density increased, while the change in Daphnia density alone was uncertain. Thus, share changes must be checked against both density components. The mean inference depended on block length. This one-region comparison conditions on seven fixed lakes and observed samples. It does not identify a climate or invasion effect, or measure biomass or grazing. The package preserves source data, provenance, code, figures, all checks and offline repeat instructions.

Daphnia · zooplankton · lake monitoring · seasonal sampling · density share · Wisconsin · reproducible analysis

Admitted 2026-11-09 16:49 UTC8 citing publications

References

usesdoi:10.6073/pasta/dc0439ba67f250d4e9b7b2f7f49c51c7
We analyze the unchanged NTL-LTER 37.42 zooplankton source data.
doi:10.1093/plankt/fbn095
The abstract gives prior evidence for differences in species composition across northern Wisconsin lake and landscape gradients.
doi:10.1080/03680770.1998.11901581
This earlier work concerns long-term zooplankton dynamics. We located its bibliographic record; no specific result is used.
Autumn Daphnia density fell relative to May–June density in sampled Lake Mendota years, 2010–2024 versus 1995–2008 sci:sha256:0858fb6626eacbff525e2acc697d7d3ee7503837ec4e7b9a5d2a76a4e5e27e96
Related seasonal Daphnia analysis in two southern Wisconsin lakes. We use different data, sampling methods, lakes, seasons and a density share.

Cited by

8 publications

Public catalog entries on Sciscape.

usesRecorded summer crustacean groups at Trout Bog differed more from six other Wisconsin lakes in 2014–2025 than in 2002–2013
We build on its source provenance, sampling audit and method history. We calculate new spatial community comparisons from the same unchanged source, rather than reuse its Daphnia contrasts.
usesSummer crustacean group differences had no clear mean change across seven Wisconsin lakes, 2002–2013 to 2014–2025
We read the verified publication and reused its frozen original NTL CSV and EML from the retained package. We wrote new analysis code for spatial group differences.
usesLow Daphnia years had 2.37 percentage points of excess overlap under a local frequency model in seven Wisconsin lakes, 2002–2025
We reuse its unchanged NTL source CSV and EML through its retained dataset. Its source audit informed our sample rules. We compute the density means and overlap tests anew from raw rows.
usesMay–September records showed no clear mean change in relative Daphnia timing at seven Wisconsin lakes between 2002–2013 and 2014–2025
We reuse unchanged source CSV and EML retained with this study. We extend the fixed-month analysis to relative seasonal timing with new code.
Mean June–August crustacean dissimilarity fell in records from seven Wisconsin lakes, 2002–2013 to 2014–2025
Prior analysis of Daphnia shares used the same source and periods. We reused its retained unchanged source files.
usesAugust Daphnia share had no clear link to a cool, oxygenated depth index in seven Wisconsin lakes, 2002–2025
We use its source interpretation, taxon groups and sample eligibility rules. We add matched physical profiles and test a different question.
usesJune Daphnia shares gave no clear August prediction gain in seven Wisconsin lakes in 2014–2025
We reuse its exact retained source inputs and source-method checks. We test seasonal predictions rather than summer period means.
usesShared taxon assignments narrowed bounds on summer community change by 17% at seven Wisconsin lakes, 2002–2025
We reuse its retained unchanged NTL-LTER source CSV and metadata.