LAUSR

ABSTRACT Trent T, Hendrickson J, Harwell MC. 2017. A rapid, cost-effective screening tool for measuring Chl-a in water samples. Lake Reserv Manage. 00:1–6 A rapid, cost-effective method for assessing chlorophyll a (Chl-a) concentrations in freshwater streams and lakes can provide an important screening tool for tracking algal blooms. While the laboratory analysis of field samples by spectrophotometer or high-performance liquid chromatography remains the optimal method for characterizing phytoplankton photosynthetic pigments, laboratory analysis can be time- and cost-prohibitive when collecting numerous samples to assess spatial or temporal aspects of a bloom. In 2011, we explored the utility of an inexpensive hand-held chlorophyll content meter (CCM; CCM-200 plus, Opti-Sciences, Inc.), normally used for leaf chlorophyll measurements, to assess Chl-a in water samples from the lower St. Johns River. CCM measurements were made on microfiber filter paper through which 200–600 mL of river water had been filtered. Chl-a sample concentrations ranged from 0.005 to 0.120 mg/L. For samples collected in open water and mid-channel habitats, CCM readings were strongly predictive of laboratory-derived Chl-a concentrations (R2 = 0.91; P < 0.01). For samples collected from near-shore vegetated habitats, the relationship between the 2 methods was weaker (R2 = 0.56), but still significant (P < 0.01). The composition of the phytoplankton community did not affect the relationship between CCM readings and Chl-a values. We believe this CCM provides a useful screening tool for rapid measurement of Chl-a concentrations in the lower St. Johns River and has the potential for being an algal bloom screening tool elsewhere. However, we emphasize that calibrations are required for applying our method in different water bodies.