Electrophysiological monitoring of nutrient stress in Oscillatoria sp. cohorts: Toward an early-warning tool for harmful algal blooms

Duci, Damiano, Amaral, Raquel, Silva, David M.S., Cotta, Francisco C., Bacellar, Felipe L., Bryant, Lee, Perkins, Rupert G. ORCID: https://orcid.org/0000-0002-0810-2656 and Rocha, Paulo R.F. 2025. Electrophysiological monitoring of nutrient stress in Oscillatoria sp. cohorts: Toward an early-warning tool for harmful algal blooms. MRS Advances 10.1557/s43580-025-01486-3

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Abstract

Cyanobacterial harmful algal blooms (HABs) are a growing challenge for freshwater management, traditionally addressed through phosphorus (P) limitation strategies. However, increasing evidence highlights nitrogen (N) availability as a key driver of bloom initiation and persistence. Here, we report extracellular voltage recordings from Oscillatoria cohorts exposed to four days of N starvation followed by ammonium (NH₄⁺) repletion using 5 mg L−1. Under N deprivation, electrical signalling developed progressively with a median of 1–2 events min−1 and amplitudes between 3-4 µV on day 1 and 2, following a marked increase in activity by days 3 and 4, with median spike rates of 5 events min−1 and amplitudes up to 17 µV. Following NH4+ repletion, signalling activity declined within 24 h, indicating rapid restoration of N balance. These results suggest that electrophysiological monitoring can serve as a real-time, non-invasive indicator of nutrient stress in Oscillatoria and provides a potential early warning tool for HAB onset and associated taste and odour (T&O) outbreaks in freshwater systems.

Item Type:	Article
Status:	In Press
Schools:	Schools > Earth and Environmental Sciences
Publisher:	Springer
ISSN:	2059-8521
Date of First Compliant Deposit:	12 December 2025
Date of Acceptance:	3 December 2025
Last Modified:	16 Dec 2025 14:00
URI:	https://orca.cardiff.ac.uk/id/eprint/183177

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