Tracking seed-dispersing piranha in the Amazon

Fish are probably not the first animals that leap to mind when thinking of seed dispersers. Squirrels are well-known examples, but researchers have recently tracked a species of frugivorous—that is, fruit-eating—piranha in the Amazon that distribute seeds over more than five kilometers of flood plains. As Daniel Cressey described in a Nature News article, “Although fish have long been suspected of having an important role in seed distribution, proof of their ability to carry fertile seeds such distances has been lacking.” Ecologist Jill Anderson from Duke University and colleagues tracked the fish Colossoma macropomum—also called a tambaqui or pacu—during three flood seasons in Peru’s Pacaya-Samiria National Reserve. As they reported in a paper published today in Proceedings of the Royal Society Biological Sciences, these fish are dispersing seeds at some of the greatest distances ever reported by frugivores. And because the seeds are dispersed in flood plains, they have a good chance of germination once the waters recede. Ed Yong reported in Discover’s blog Not Exactly Rocket Science that “seeds find it slightly easier to germinate after a voyage through the tambaqui’s innards.” By tracking these fish, Anderson also found evidence that the populations are depleted due to overfishing. That is, she was unable to find any fish close to maximum size within the three seasons she was tracking them. As Yong concluded his post, “Other species of fruit-eating fish are facing similar problems. So fishermen are not only depriving the Amazon of some of its most effective seed dispersers, they are also taking the best carriers out of the game. In doing so, they are disrupting alliances between fish and plants that have been going on for millions years. And they risk the future of the same flooded forests that provide them with their livelihoods.” Photo Credit:...

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The tiny, diligent gardeners of the Amazon

The gardeners described here are not concerned with trimmed topiaries or manicured lawns—though, like designers of landscape gardens, these workers are exceptionally picky. And they have to be if they are going to survive. That is, ants such as Myrmelachista schumanni and Camponotus femoratus of South America depend on certain plants for shelter, and in return, they offer these plants nutrients and protection from predators. As a result, they have developed a mutualistic relationship that has led to an incredible resilience for both species. For example, the ant M. schumanni has kept the plant Duroia hirsute alive in one area of the Amazon, known as a devil’s garden to locals, for more than 800 years. This particular type of ant-plant dependency is plentiful in the Amazon and it creates eerie patches of monoculture gardens amidst the rest of the lush, diverse rainforest. As biologist and photographer Alex Wild described in a recent Myrmecos blog post (complete with photos): I had been following an army ant raid for half an hour through dense tropical forest when the trees unexpectedly parted to reveal a small clearing. Sun broke through the canopy and fell on a low tangle of furry plants. It was a monoculture, looking as though planted by a reclusive sort of gardener. I had stumbled into a Devil’s Garden. Local lore holds that malevolent forest spirits create these unnatural crop circles, but the truth is just as weird. Devil’s Gardens are [cultivated] by ants. The plant species that compose these gardens—mostly in the genera Tococa, Clidemia, and Duroia—sport swollen structures filled by the nests of tiny Myrmelachista ants no more than 3 millimeters long. The ants are meticulous about caring for their hosts, removing [pesky] herbivores and injecting formic acid into the saplings of competing plants. Another ant species, C. femoratus, gathers the seeds of particular plants to cultivate in its nests, called ant gardens, and made of a mixture of animal feces, digested plants and other organic material. These nests are attached to vines, the sides of trees and even high up in the tree canopy. As Elsa Youngsteadt explained in the podcast Curiouser and Curiouser, ants followed chemical signals given off by seeds of certain plants, collected the seeds, carried them back and embedded them in the walls of the nests. The plants benefitted from the fertilizer mixed in the nest, and in turn, the roots helped to add structure to the ant garden. In addition, the leaves protected it from heavy rains that would otherwise have caused the material to disintegrate. “There are about ten plant species that are in ant gardens regularly that you don’t...

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Living video games, seed science and bat rescues

Video games that guide the movement of paramecia, dogs trained to aid in data collection, the evolution of seeds in the Amazon Rainforest, environmental degradation captured as art and the successful rescue of more than 100 bats stranded by the devastating floods in Australia. Here are stories in ecology for the third week in January 2011. PAC-mecium: Stanford University researchers have developed, not a life-like video game, but a video game that incorporates life into its programming, according to New Scientist. “A game called PAC-mecium is Pacman with a twist: players use a console to change the polarity of an electrical field in a fluid chamber filled with paramecia, which makes the organisms move in different directions,” explained the article. As shown in the above video, the user shapes the behavior of the organisms according to what the game board shows, such as avoiding “Pacman-like fish.” Read more at “Play Pacman, Pinball and Pong with a paramecium.” Beautiful and dangerous: There has been quite a bit of news surrounding an increase in the prevalence of jellyfish in China, Australia, North America and around the world; the population boom has been linked to ocean acidification, overfishing and climate change. Researchers suggest that the jellyfish numbers indicate a larger issue of imbalanced ecosystems and an overall decline in ocean health. While often times beautiful, jellyfish can also pose a risk to humans and other marine life and have even caused power outages. Scat hunters: According to The New York Times, researchers have been using dogs to sniff out scat, making it easier to collect population distribution data. A study published recently in The Journal of Wildlife Management examined factors that would affect the dogs’ abilities to detect scents in the field. “Trained dogs can detect scat up to 33 feet away about 75 percent of the time, the researchers found,” wrote Sindya Bhanoo. “Humans, on the other hand, can see scat only within three to five feet.” Read more at “Four-Legged Assistants Sniff Out Wildlife Data.” The science of seeds: Botanists examined some of the seeds found in the Amazon Rainforest and cataloged the evolution, distribution and role that these seeds play in the most diverse rainforest in the world. “Some [of the seeds] look like brains, some like arrowheads, others like beads, propellers or puffs of cotton,” began the Scientific American article. “Seeds have evolved many of these striking features to help them propagate in the wild.” Read more at “Seeds of the Amazon” or view the slide show. Degradation as art: The New York Times highlighted the work of photographer J. Henry Fair, who collects aerial images of environmental degradation...

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From the Community: Colonizing the oceans, fact-checking nursery rhymes and urbanizing mollusks

Aquanaut describes plans to colonize the sea for education and conservation, a pitcher plant previously thought to be carnivorous has been wildly reclassified and the first condor egg in 100 years discovered in California. Here are news stories and studies on ecological science from the second week in March.

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