Sugar mountains found under seagrass meadows

Scientists from the Max Planck Institute for Marine Microbiology in Bremen, Germany have reported that the seagrasses release huge quantities of sugar, largely in a sucrose form, into their soils. 

The research was carried out off the Italian island opf Elba, and the amount released worldwide is estimated to be a million tonnes of sucrose, which would be enough for 32 billion cans of coke, the scientists believe. It is 80 times more than has previously been measured in marine environments.

”Such high concentrations of sugar are surprising,” said Maggie Sogin, first author of the report published in Nature Ecology & Evolution. “Normally, micro-organisms quickly consume any free sugars in their environment. It is easy to di­gest and full of en­ergy. So why is­n’t the sucrose con­sumed by the large com­munity of mi­croor­gan­isms in the seagrass rhizo­sphere? We spent a long time try­ing to fig­ure this out

”What we realised is that seagrass, like many other plants, release phenolic compounds to their sediment. Red wine, cof­fee and fruits are full of phen­olics, and many people take them as health sup­ple­ments. What is less well known is that phen­olics are an­ti­mi­cro­bi­als and in­hibit the meta­bol­ism of most mi­croor­gan­isms.

“In our ex­per­i­ments we ad­ded phen­olics isol­ated from seagrass to the mi­croor­gan­isms in the seagrass rhizo­sphere – and in­deed, much less sucrose was con­sumed com­pared to when no phen­olics were present.”

Seagrasses are abundant in many coastal regions. They are considered to be one of the most efficient absorbers of carbon dioxide - one square kilometre stores almost twice as much as forest on land, and 35 times as quickly.