A case study of adapting PhytoPAM II and factory reference spectra for a multi-lake monitoring program

Résumé fourni par la source

Leung T, Lee J, Choi J, Yang J, Ikuma K, Howe AC, Swanner ED. 2026. A case study of adapting PhytoPAM II and factory reference spectra for a multi-lake monitoring program. Lake Reserv Manage. XXX–XXX.The PhytoPAM II quantifies and attributes chlorophyll a (Chl-a) to 4 phytoplankton groups based on their unique fluorescence excitation spectra (FES): (1) “blue” group for cyanobacteria; (2) “green” group for euglenophytes and chlorophytes; (3) “brown group” for ochrophytes (e.g., diatoms), dinophytes, haptophytes; and (4) “red” group for phycoerythrin-rich phytoplankton. This rapid assessment is potentially advantageous over microscopy for monitoring algal blooms. However, calibrating the FES for more than one lake or as the community composition changes can pose a challenge for lake monitoring programs. This study assessed using the PhytoPAM II and its factory reference FES to estimate phytoplankton biomass (as Chl-a) and characterize phytoplankton community changes in a suite of freshwater lakes located in the midwestern United States. Subsurface water samples (n = 450) were collected during 3 summers (2018–2020; 15 weeks per summer). PhytoPAM II-derived Chl-a were compared with Chl-a extractions. Phytoplankton community composition was compared with 16S or 18S rRNA sequencing and optical microscopy. There was a significant correlation between spectrophotometric and PhytoPAM II-derived Chl-a (R2 = 0.92; p < 0.001) across lakes in 2 study years. The factory reference FES correctly discriminated major taxa belonging to the “blue” group (95% occurrences detected) and “brown” group (94% occurrences detected); however, taxa belonging to the less abundant “green” and “red” groups may go undetected (67% and 61% occurrences detected, respectively). The adaptation of PhytoPAM II and its factory reference FES for near real-time phytoplankton community assessment can serve as a first line of monitoring of cyanobacterial-dominated lakes.

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