Highlights from the October 2014 issue of the Ecological Society of America’s journal Ecology, published online today.
Invasive seaweed shelters native crustacean
A Japanese seaweed gains a holds on a mudflat in Charleston Harbor, S.C., by clinging to tube-building decorator worms (Diopatra cuprea) rooted firmly in the mud. The invasive Gracilaria vermiculophylla seaweed provides shelter for a small native crustacean. Credit, Erik Sorka.
The tall, mature trees of a late-succession forest (right) stand next to the young regrowth of a clear-cut forest in central Pennsylvania. The deeper volume of organic matter on the floor of a mature forest can capture more of the nutrient nitrogen when it enters the forest than the clear-cut can. Credit, David Lewis.
On the tidal mudflats of Georgia and South Carolina, the red Japanese seaweed Gracilaria vermiculophylla is gaining a foothold where no native seaweeds live. Only debris and straggles of dead marsh grass used to break the expanse of mud at low tide. Crabs, shrimp, and small crustaceans mob the seaweed in abundance. What makes it so popular?
Not its food value. On mudflats near Savannah, Ga., Wright and colleagues found that the tiny native crustacean Gammarus mucronatus (one of the 9,500 species of amphipod, which includes sand fleas) does not eat much of the seaweed. Rather, its attraction is structural. The seaweed protects the small crustaceans from predators at high tide and from the dry heat of the flats at low tide. G. mucronatus was up to 100 times as abundant on seaweed invaded mudflats.
The arrival of an aggressive invader disrupts the food webs and physical and chemical characteristics of the environment it enters. Disruption is often bad for native species that get shaded, crowded, or eaten by the invader, and reports of the disastrous consequences of invasive species have grown familiar. But the story for individual species is more complicated, as the presence of the invader is sometimes a benefit, either as a new source of food or, as in this case, of shelter.
Engineering or food? Mechanisms of facilitation by a habitat-forming invasive seaweed (2014) JT Wright, JE Byers, JL DeVore, and E Sotka. Ecology 95(10): 2699-2706. http://dx.doi.org/10.1890/14-0127.1 [open access]
Mature forests store nitrogen in soil
Ecologists working in central Pennsylvania forests have found that forest top soils capture and stabilize the powerful fertilizer nitrogen quickly, within days, but release it slowly, over years to decades. The discrepancy in rates means that nitrogen can build up in soils. Forests may be providing an unappreciated service by storing excess nitrogen emitted by modern agriculture, industry, and transport before it can cause problems for our waterways.
Nitrogen is an essential nutrient, required for all living things to live and grow. Though a major component of the air, it is largely inaccessible, captured only through the metabolism of certain microbes or washed to earth in the form of ammonia, nitrogen oxides, or organic material by rain, snow, and fog. On land, microbes, fungi, and plants incorporate what doesn’t wash away into proteins, DNA, and other biological components. Organic matter in the soil – the remains of fallen leaves, animal droppings, and dead things in various states of decay – can also capture newly deposited nitrogen, holding it stable in the soil.
Mature forests store nitrogen more efficiently than young forests recovering from clear-cuts the authors found, because they have been accumulating organic matter on the forest floor for a century or more. When a forest is clear cut, erosion soon follows, washing away top soil. A young stand of trees a decade old is beginning to rebuild the organic layer, but it will take many autumns to accumulate.
The orderly succession of changes in resident species as a forest grows and ages is a classic preoccupation of ecological theory. The exchange of nutrients among the species and the non-living landscape also changes with succession, and the discovery that nitrogen accumulates in the organic soil indicates something important about how an ecosystem’s nutrient economy ages. It was thought, up through the 1970s and early 80s, that an ecosystem grows like a person. At some point, forests, like people, stop getting bigger and adding new biomass. Ecologists argued that the ability to capture incoming nutrients stopped with the end of growth. But by the mid-80s, it was clear that mature ecosystems did continue to absorb nitrogen, mostly in soil. By showing that nitrogen capture is much faster than its release, Lewis and colleagues suggest a mechanism by which old ecosystems can accumulate new inputs of nutrients.
Because soils rich in organics can quickly incorporate nitrogen, forest soils have the potential to absorb excess nitrogen that has been newly added to the biosphere through human activities. Application of synthetic nitrogen fertilizers and combustion of fossil fuels produce substantial amounts of ammonia and nitrogen oxides. Since industrialization, human activities have tripled the global rate of fixation of nitrogen from the air. The excess has perturbed the nutrient economies of many ecosystems, most visibly by feeding algal blooms and oxygen-deprived dead zones in lakes and estuaries. The study suggests that we may want to strategically conserve or restore forests, preserving organic-rich soils where they intercept the movement of ground water towards streams, lakes, or estuaries.
Forest succession, soil carbon accumulation, and rapid nitrogen storage in poorly-remineralized soil organic matter (2014) DB Lewis, M Castellano, and JP Kaye. Ecology 95(10): 2687-93. http://dx.doi.org/10.1890/13-2196.1 [open access]
In streams around the world, small animals feeding at the bottom of the food chain are not eating the selection of decaying leaves, slimy film streambed films, and fine particulate detritus that ecologist have presumed they eat.
You are not always what we think you eat: selective assimilation across multiple whole-stream isotopic tracer studies. (2014) W. K. Dodds, S. M. Collins, S. K. Hamilton, J. L. Tank, S. Johnson, J. R. Webster, K. S. Simon, M. R. Whiles, H. M. Rantala, W. H. McDowell, S. D. Peterson, T. Riis, C. L. Crenshaw, S. A. Thomas, P. B. Kristensen, B. M. Cheever, A. S. Flecker, N. A. Griffiths, T. Crowl, E. J. Rosi-Marshall, R. El-Sabaawi, and E. Martí. Ecology 95(10):2757–2767. http://dx.doi.org/10.1890/13-2276.1
ESA is the world’s largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 10,000 member Society publishes six journals and broadly shares ecological information through policy and media outreach and education initiatives. The Society’s Annual Meeting attracts over 3,000 attendees and features the most recent advances in ecological science. Visit the ESA website at http://www.esa.org.
Liza Lester | Eurek Alert!
When corals eat plastics
24.05.2018 | Justus-Liebig-Universität Gießen
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences