In a recent report in the journal Science, researchers from the Woods Hole Oceanographic Institution (WHOI) found abundant colonies of Trichodesmium. The multi-celled, filamentous organism is thought to play a significant role in the input of nitrogen to the upper layers of the tropical and subtropical ocean, nearly half of the Earth’s surface.
The video plankton recorder (VPR) on the deck of research vessel Oceanus. (Photo by Cabell Davis, Woods Hole Oceanographic Institution)
Collage of images of Trichodesmium collected by the video plankton recorder. The spherical images are the puffs and the elongated images the tufts. (Courtesy Cabell Davis, Woods Hole Oceanographic Institution)
Lead author Cabell Davis, a senior scientist in the WHOI Biology Department, and co-author Dennis McGillicuddy, an associate scientist in the WHOI Applied Ocean Physics and Engineering Department, suggest that nitrogen fixation rates for Trichodesmium may be 2.7 to 5 times higher than previously estimated from traditional sampling.
Trichodesmium is one of many tiny photosynthetic organisms that use the sun’s energy, carbon dioxide and other nutrients to make organic material that constitutes the basis of the marine food web. Production of biomass in surface waters is typically limited by nitrogen, but Trichodesmium is able to escape that constraint by virtue of its ability to utilize nitrogen gas, which is plentiful in the atmosphere and upper ocean.
Trichodesmium abundance has been difficult to measure using traditional net sampling because the colonies are easily damaged or destroyed during collection. Sampling with bottles has provided estimates of abundance of the organism, but it is a snapshot view.
The Video Plankton Recorder (VPR) is a noninvasive instrument, consisting of a digital video-microscope on a towed vehicle that samples at 30 frames per second and automatically sorts the Trichodesmium images from other organisms.
“If traditional sampling has underestimated colonies in other regions of the world, our estimates of global Trichodesmium abundance will increase dramatically,” Davis said. “That increase could potentially account for a significant portion of the global nitrogen cycle, thus changing our perception of the importance of this organism to the productivity of the world ocean.”
Davis and McGillicuddy towed the VPR across the North Atlantic between the Azores and the Slope Water south of Woods Hole in 2003, skirting category 3 hurricane Fabian. The vehicle was towed at six meters per second, about 12 nautical miles an hour, surveying continually and automatically between the surface and about 130 meters (400 feet) deep like a yo-yo. Nearly 7,000 vertical profiles were taken during the 5,517 kilometer (about 3,443 miles) transit across the North Atlantic.
While the colonies of Trichodesmium are fragile and thought to be destroyed when mixed by strong winds, the team found no evidence that hurricane Fabian, with winds up to 200 kilometers an hour (about 125 miles per hour), had caused them any damage. The team sampled the upper layers of the ocean across the wake of the storm.
The researchers also found a strong correlation between temperature, salinity and abundance of Trichodesmium colonies in the various eddies and the Gulf Stream the VPR crossed during its survey.
Two forms of Trichodesmium, called puffs and tufts because of their shapes, were found in higher concentrations in warm salty water. Higher concentrations of the organism were also found in warm anticyclonic eddies than in cold cyclonic ones, but the reasons are unclear.
Davis and McGillicuddy are doing similar survey aboard WHOI’s research vessel Knorr, which just passed through the Panama Canal. The researchers will deploy the VPR and survey across the Caribbean Sea, a region known to have very high concentrations of Trichodesmium. The ship will arrive back at Woods Hole on June 29.
Davis says the new Caribbean VPR survey will provide much needed information about Trichodesmium population estimates in its tropical home, information that has been difficult to obtain due to the patchy nature of the species in ocean waters.
The project was supported by the Richard B. Sellars Endowed Research Fund, the Andrew W. Mellon Foundation Endowed Fund for Innovative Research, the WHOI Ocean Life Institute, the National Science Foundation and NASA.
Shelley Dawicki | EurekAlert!
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
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