Cyanobacterial blooms in a warming climate: Paleolimnological assessments of three Boreal Shield lakes in central Ontario, Canada

Paleolimnological techniques were used to assess long-term water quality changes in three cyanobacterial bloom-impacted lakes in Algoma, Ontario, Canada. Since the 2000s, frequent cyanobacterial blooms have been reported in these lakes despite stable nutrient levels, allowing investigation of recent climate warming as a possible environmental driver of the blooms. While diatom and chironomid community changes varied among the lakes, accelerated warming (~1990) led to near-synchronous shifts in paleolimnological indicators, including increased sedimentary chlorophyll a, planktonic diatoms (Discostella stelligera, elongate taxa), and chrysophyte scales. Diatom-inferred total phosphorus and chironomid-inferred hypolimnetic oxygen models indicate oligo-mesotrophic conditions prior to ~1950, with slightly higher late-summer oxygen concentrations in Desbarats and Bright lakes. Our results suggest a shift towards enhanced thermal stability due to regional warming, supported by instrumental rec..., , , # Cyanobacterial blooms in a warming climate: Paleolimnological assessments of three Boreal Shield lakes in central Ontario, Canada

Dataset DOI: [10.5061/dryad.5x69p8dg1](10.5061/dryad.5x69p8dg1)

## Description of the data and file structure

These data were collected for [E.J. Favot's PhD thesis](https://qspace.library.queensu.ca/items/78c3ca76-5c02-4785-994f-25593762d355), Investigating Long-term Environmental Trends in Central Ontario Lakes Impacted by Cyanobacterial Blooms. Queen's University. 2021.

Raw species count data for diatoms and chironomids are presented within this thesis in Appendix D and Appendix E, respectively.

### Files and variables

#### File: Pb-210_Dates.csv

**Description:** Lead-210 CRS dates and isotope activities used to establish sediment core chronologies for Bright, Desbarats and Caribou lakes. Null values are indicated where Pb-210 isotope activities were too low to allow estimation of dates and sedimentation rates (i.e. beyond \"background\" concentrati...,