WHAT THE EVIDENCE SAYS
Using 2013–2023 national monitoring data, researchers used binary logistic regression to calibrate Secchi-depth boundaries against phytoplankton and macrophyte ecological status for three lake types. The resulting thresholds were 0.6 m for very shallow lakes, 1.4–1.5 m for shallow lakes and 3.1 m for deep lakes, with moderate-to-good predictive performance.
WHY IT MATTERS / OUR READ
Simple field measurements become more useful when their thresholds are locally anchored to ecological response. The work is a good example of translating a cheap, repeatable indicator into a management boundary without pretending one universal Secchi depth fits every lake.
CAVEATS / UNCERTAINTY
The boundaries are specific to Greek natural-lake types and Water Framework Directive classification. They are statistical support thresholds, not universal ecological tipping points, and should be recalibrated before use in other limnological settings.
SOURCE
Hydrobiologia — primary study
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