Photosynthesis and circadian rhythms regulate the buoyancy of marimo lake balls

• Published in: Current Biology
• Main Authors: Cano Ramirez, Dora, de Fraine, Saskia, Griffiths, Olivia, Dodd, Antony
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: Ramirez; Iceland
• Online Access: https://hdl.handle.net/1983/2ab93368-c54a-4003-ab90-d53fafd489b7; https://research-information.bris.ac.uk/en/publications/2ab93368-c54a-4003-ab90-d53fafd489b7; https://doi.org/10.1016/j.cub.2018.07.027; https://research-information.bris.ac.uk/ws/files/166038922/1_s2.0_S0960982218309266_main.pdf; http://www.scopus.com/inward/record.url?scp=85051528192&partnerID=8YFLogxK

Marimo are unusual, attractive and endangered spherical aggregations of the filamentous green macroalga Aegagropila linnaei (Figure 1A–E) [1]. Globally rare, marimo populations persist in cold freshwater lakes in Japan, Iceland and Ukraine. Marimo occupy both the lake bed and rise to the lake surface [2,3]. Here, we show that marimo buoyancy is conferred by bubbles arising from photosynthesis. We find that light-induced acquisition of buoyancy by marimo is circadian-regulated. We identify that there are circadian rhythms of photosynthesis in marimo, which might explain the circadian rhythm of buoyancy in response to light. This identifies a circadian-regulated buoyancy response in an intriguing and little-studied plant. Cano-Ramirez et al. show that marimo lake balls are buoyant in the light because photosynthesis causes bubbles to form on the balls. They identified a circadian rhythm in the time marimo take to become buoyant, and identified circadian rhythms of photosynthesis in marimo. These processes might underlie movements of marimo within the water column.