Fluorometry for Rapid Eutrophication Status and Cyanobacteria Assessment (FRESCA)

Eutrophication of inland waters causes increased occurrence of cyanobacterial blooms, requiring intensive monitoring. FRESCA provides a theoretical basis, prototypes, testing and commercialisation of a low-cost mobile fluorescence sensor. The sensor exploits fluorescence excitation and emission properties of cyanobacteria, which are often poorly dealt with in fluorometers. A mechanistic interpretation of the measured signal provides unambiguous diagnosis of cyanobacteria status of natural waters.

The project will include sensor prototyping (by industrial partner Chelsea Technologies Group), laboratory experiments, optical simulations (Plymouth Marine Laboratory) and performance tests and validation in nature (University of Stirling). Lab experiments will characterize diagnostic cyanobacterial fluorescence properties which the sensor will exploit, including: (A) weak millisecond-fluorescence response to saturating light at wavelengths corresponding to photosystem-I compared to photosystem-II emission [2]; (B) reversible uncoupling of phycobilisomal energy transfer under saturating light with emission shifting from 670 nm to shorter wavelengths, within minutes of exposure, and (C) weak but measurable inducibility of phycobilisomal fluorescence at 670 nm and fluorescence quenching at the phycobilisome under prolonged light exposure. These laboratory characterizations will be used to build a model of cyanobacteria fluorescence induction, in turn used to define minimum and ideal sensor specifications. These will be developed into a series of prototypes that will be tested in the field.