The alga, called Didymo for Didymosphenia geminata, does so with a little help from its friends -- in this case, bacteria-- which allow it to make use of nutrients like phosphorus.
Blooms of Didymo, also known as "rock snot," are made up of stalks that form thick mats on the beds of oligotrophic (low-nutrient) streams and rivers, says scientist P.V. Sundareshwar of the South Dakota School of Mines and Technology in Rapid City. Sundareshwar is the lead author of the paper, published on 28 May in Geophysical Research Letters, a journal of the American Geophysical Union.
"In recent decades, human activities have led to many uncommon environmental phenomena," he says. "Now we have Didymo."
The freshwater diatom has become notorious. Didymo has taken over oligotrophic rivers in North America and Europe. It has also invaded water bodies in the Southern Hemisphere, including those in New Zealand and Chile.
Because its blooms alter food webs and have the potential to impact fisheries, "Didymo presents a threat to the ecosystem and economic health of these watercourses," says Sundareshwar.
Algae blooms are usually linked with the input of nutrients that fuel the growth of microscopic aquatic plants. Didymo's ability to grow prolifically in waters where nutrients such as phosphorus are in short supply had puzzled scientists.
Environmental managers had tried to mitigate Didymo blooms and predict their spread. But how the diatoms sustained such high growth in oligotrophic systems was unknown.
In the study, Sundareshwar and colleagues revealed that Didymo is able to concentrate phosphorus from the water.
The scientists conducted their research in Rapid Creek, an unpolluted mountain stream in western South Dakota where Didymo was first observed in 2002. The creek regularly has Didymo blooms, with 30 to 100 percent of the streambed covered with Didymo over an area up to ten kilometers (6.2 miles) long.
Didymo thrives in Rapid Creek through biogeochemical processes in biofilms in the mats. As Didymo mats develop, new stalks develop at the surface and older stalks-which have already bound phosphorus-are displaced to the mats' inner regions.
Phosphorus is available to Didymo thanks to the activity of the bacteria that live inside these mats.
"This study solves the puzzle of how Didymo can produce such large blooms in low-nutrient rivers and streams," says Tim Kratz, program director in the National Science Foundation's (NSF) Division of Environmental Biology.
"It has uncovered the fascinating mechanism by which Didymo 'scrubs' phosphorus from a stream or river," says Kratz, "then creates a microenvironment that allows microbes to make this nutrient available for Didymo's growth."
The concentration of phosphorus on Didymo mats far exceeds the level that was expected based on the nutrient content of surface waters, says Sundareshwar. "The ability of the mats to store phosphorus is in turn tied to the availability of iron in the water."Didymo cells adsorb (collect on their surfaces) both iron and phosphorus. Then bacterial processes in the mat interact with iron to increase the biological availability of phosphorus.
The process results in abundant phosphorus for cell division, "and hence," says Sundareshwar, "a resolution to the paradox of Didymo blooms in oliogotrophic streams and rivers."
The result may help managers identify water bodies susceptible to Didymo blooms, and develop management strategies.
"It also has the potential to lead to discoveries that may stem this organism's prolific growth in rivers around in the world," says Sundareshwar.
This study was funded by NSF and the State of South Dakota Carbon Scientist fund.Notes for Journalists
Or, you may order a copy of the paper by emailing your request to Maria-Jose Vinas at email@example.com. Please provide your name, the name of your publication, and your phone number.
Neither this paper nor this press release are under embargo.Title:
Institute of Atmospheric Sciences, South Dakota School of Mines and Technology, Rapid City, South Dakota, USA;
B. Berdanier: Deparment of Civil and Environmental Engineering, South Dakota State University, Brookings, South Dakota, USA;
S. A. Spaulding: INSTAAR, U.S. Geological Survey, Boulder, Colorado, USA.Contact information for the author:
Maria-Jose Vinas | American Geophysical Union
In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy