Too many nutrients make microbes less responsive

The University of Minnesota has just completed a study showing that “too many nutrients make microbes less responsive”.

The article states that bacteria (such as cyanobacteria/blue green algae) play an important role in the health of a lake as they absorb phosphorus and nitrogen and store carbon, however their ability to do this has found to be dependent on the water chemistry of the lake that they live in.

The author of the study, Professor Jim Cotner, stated that “in some ways, adding too much phosphorus and nitrogen to lakes is similar to what happens with Type II diabetes–our lakes are becoming less able to respond to increasing carbon just as humans with diabetes become less able to respond to insulin in their body.” “Too much of a good thing can lead to metabolic dysfunction that can be catastrophic.” 

The study looked at data from 35 lakes throughout Minnesota. The researches stated that “other work has shown that lakes with more phosphorus and nitrogen have different species of microbes, plants, insects, and animals than more pristine lakes, but this is the first study to show that the species in polluted lakes are less able to respond to further added nutrients and perhaps more importantly, carbon. If more of the CO₂ we produce is absorbed by microbes and plants in lakes, oceans, and other ecosystems, that means less CO₂ will accumulate in Earth’s atmosphere.” 

“When we compared the bacteria from the most phosphorus rich lakes to bacteria from lakes that were more pristine, one of the big differences was that the microbes from lakes with lots of phosphorus were less able to remove carbon from the water”. This has huge implications on future uptake of CO₂ by aquatic organisms and the future concentration that could accumulate in the atmosphere.

This work highlights the importance of continued regulation and reduction of phosphorus in lakes and lake sediments. Phoslock binds phosphorus and forms a new inert mineral Rhabdophane. In this form, the phosphorus concentration is significantly reduced in eutrophied lakes and is no longer available for uptake and by cyanobacteria. This study also shows how unmonitored phosphorus accumulation in lakes can have larger implications to the global environment.

The article can be found at: https://www.eurekalert.org/pub_releases/2017-12/uom-stm121117.php