On the 20th of March 2020, a phenomenon of bioluminescence was witnessed in the Cochin estuary. The cause of the event was an algal bloom of Gonyaulax spinifera, a species that is known for its bioluminescent capabilities. To measure the response of G. spinifera to the various mechanical stimuli in situ, the Glowtracka sensor was used. A single channel sensor attached to a Conductivity–Temperature–Depth Profiler, Glowtracka was able to measure the bioluminescence intensity (BI) in the area.
In a steady environment, without any external stimuli, the bioluminescence was not detected by the Glowtracka sensor. However, when a hand splash, oar and swimming movements, and a mixer were applied, the BI was recorded to be as high as 1.6 × 1011 photons cm−2 s−1. The abundance of the cells was estimated to be 2.7 × 106 cells L−1, and the chlorophyll a was found to be 25 mg m−3. The BI was recorded to be 1–6 × 1010 photons cm−2 s−1, with a cumulative bioluminescence of ~ 2.51 × 1012 photons cm−2 (for 35 s) when the mixer was applied with a constant force of 494 N/800 rpm min−1. The Glowtracka sensor was able to measure the BI in response to the various mechanical stimuli.
The BI was highest in the periphery of the turbulent wake generated by the stimuli (av. 3.1 × 1010 photons cm−2 s−1) compared to the center (av. 1.8 × 1010 photons cm−2 s−1). When the stimuli was applied vertically down, the BI decreased from 0.2 m (0.3 × 1010 photons cm−2 s−1) to 0.5 m (0.10 × 1010 photons cm−2 s−1). The Glowtracka sensor proved to be a highly useful tool in the study of G. spinifera‘s response to mechanical stimuli. It was able to measure the bioluminescence intensity (BI) accurately, and showed that the BI increases with increased mechanical stimuli, and decreases with increased distance from the stimuli source.
The study also demonstrated that the BI remains high even with the application of stimuli for longer time periods, due to the replenishment of water from surrounding areas. The Glowtracka sensor opened a new avenue for studying bioluminescence and its response to stimuli, and has proven itself to be a powerful tool for measuring BI accurately.
Detect red-tide outbreaks with Glowtracka
Chelsea Technologies’ GlowTracka detects bioluminescence from dinoflagellates and similar organisms. Originally developed by Plymouth Marine Laboratory in the UK, GlowTracka’s precision flow meter stimulates bioluminescent organisms and measures the light flashes as the organisms pass the detector, giving photon level sensitivity.
GlowTracka is highly flexible in its deployment options, including moorings, profiling (with pumped system) or deployment in towed vehicles.