Undermeasured compound could help resilience against climate change in key coastal waters

2 February 2023

A team of scientists have for the first time measured the seasonality of a widespread compound used by many species of marine plankton to survive the salty environment through spring, summer and autumn.
 
The compound, glycine betaine (GBT), is a component of the organic nitrogen pool and is often used by multiple organisms including plants on land and in water to tolerate environmental stresses, such as drought, low temperatures and high salt levels.
 
The study, led by Plymouth Marine Laboratory in partnership with the University of Warwick and funded by the Natural Environment Research Council (NERC), found that concentrations of GBT in the Western English Channel during 2016 peaked in summer and autumn. This peak corresponds with specific phytoplankton species in summer and rapidly changing salinity and nutrients availability in autumn.
 
These results suggest distinct environmental drivers for different periods of GBT seasonality, which do not follow the concentrations of the more standard measurements taken in the Western English Channel of phytoplankton biomass and chlorophyll, the green pigment in plants that is responsible for converting sunlight into energy.
 
Additionally, the team propose that GBT positively affects the fitness and flexibility of dinoflagellates, a species of plankton often dominating during summer in the Western English Channel, by having a positive feedback on growth.
 
The high cellular content of GBT may increase the buoyancy of dinoflagellates allowing them to adjust their position in the water column to optimise light and nutrient conditions. This could further help some common dinoflagellate species within the Western English Channel match the depth of their prey. These species consume cells as well as photosynthesize for food, and GBT may help them move up or down the water column to more favourable environmental conditions.
 
This beneficial effect allows the dinoflagellates to outcompete other plankton when inorganic nutrients, such as nitrogen that helps organisms grow and repair, are low or depleted. This strategy could underpin a resilience to vastly varying conditions under different climate change scenarios.
 
Lead author of the paper and Marine Biogeochemist at PML, Dr Ruth Airs, comments: “This research, has already helped improve the performance of a marine ecosystem model of the area by more accurately reproducing the increase in dinoflagellates biomass in the transition from spring to summer.”
 
“It also paves the way for future multidisciplinary research aiming to understand the importance of dinoflagellates in key coastal ecosystems and their potential significance for compounds relevant for particle growth in atmospheric chemistry”.
 
Postdoctoral Researcher at the University of Warwick and one of the co-authors, Dr. Michaela Mausz adds: “This research emphasises the importance of studying GBT, which has long been neglected in favour of the more famous, related sulphate-containing compound dimethylsulfoniopropionate (DMSP). Our data suggests an important connection between GBT concentrations and dinoflagellate dominance during summer and a possible affiliation with fitness. This might only be a first glimpse to understand the complex role this compound plays particularly with respect to climate change”.

Sampling intracellular GBT concentrations is laboursome and time consuming but important to measure and understand the drivers and impact of these changes, as concentrations are likely to shift indirectly due to climate change that could affect the local food web.
 

Related information

Full paper: Seasonal measurements of the nitrogenous osmolyte glycine betaine in marine temperate coastal waters