A Limnological Yardstick based on phosphorus limitation

Abstract Hoyer MA, Canfield DE, Jr. 2022. A Limnological Yardstick based on phosphorus limitation. Lake Reserv Manage. 38:109–125. A new tool called a Limnological Yardstick was developed using long-term (15 to 35 yr) lake chemistry data collected by volunteers of the Florida LAKEWATCH program. This yardstick can assist managers of aquatic systems with identifying where there is a great probability that phosphorus is not only the limiting nutrient, but the limiting environmental factor. When a lake’s phosphorus–chlorophyll data lie below the yardstick’s lower 95% confidence interval, phosphorus may be the limiting nutrient but not the limiting environmental factor, indicating where phosphorus control strategies will most likely fail. The Limnological Yardstick cannot directly identify the limiting environmental factor(s), as this requires a thorough limnological study of the lake because each lake has unique properties. Limiting environmental factors discussed are nitrogen, true color (Pt-Co units), nonalgal suspended solids, flushing rate, and aquatic macrophytes. The potential impacts of limiting environmental factors on the classification of lake trophic state and eutrophication are also discussed.