Project Ecophysiometer: Updates and New Features.

MARCONI, GUIDO; GOMEZ, MAURO; BUNDSCHUH, M.; AMÉ, MARÍA VALERIA

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

SETAC

Environmental inequality is exacerbated by the unavailability of environmental monitoring technologies for low income communities. The shortage of resources leads to incomplete databases with only a fraction of the relevant environmental variables being monitored. As both policy making and scientific discovery depend on the availability of high quality long term, uninterrupted data, any shortage on this end may lead to poorly managed ecosystems. As an attempt to solve this issue, the Ecophysiometer project started as an open-science initiative aiming to provide a versatile instrument capable of measuring multiple variables with a single equipment, and enabling users to develop and share customised methods and data. This work presents the improvements made to the instrument. We have developed a custom Printed Circuit Board (PCB) that interfaces with a Raspberry pi. Software was also improved by developing a series of pythonpackages that ease users developing custom routines. A graphical user interface was created to easily find optimal conditions and monitor samples’ spectra during method development or to use the ecophysiometer as a bench-top instrument. We have redesigned the instrument enabling it to measure the visible spectrum of absorbance and the emission spectra of fluorescence, at eight different excitation wavelengths (275 nm, 365 nm, 395 nm, 440 nm, 470 nm, 530 nm, 600 nm & 660 nm). The optical path-length of the absorbance measurements was enlarged to increase the sensitivity in optically thinner samples. Lastly, an auto-sampler was included in the new design. To explore the capacity of the equipment to measure several variables a series of methods were developed. Firstly, a method to measure turbidity (nephelometric turbidity units) was developed using the formazin standard proposed in SMEWW 2130 (n = 11, p-val < 2 10-16 ,R2= 0.9997).To explore the capacity of the instrument to distinguish between algae groups, pure cultures ofScenedesmus spp. and Dolichospermum spp. were measured. The resulting spectra were then clustered with hierarchical cluster analysis, resulting in a clear separation of each sample group. Encouraged by these results, we are currently working on a method to quantify chlorophyll-a and another to to quantify phytoplankton divisions' abundance.