by Kristen Minogue
Artist's depiction of the prehistoric synapsid Varanodon agilis (left) under attack from an ancient amphibian. (Wikimedia Commons/Smokeybjb)
Ecology
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Milk before dinosaurs? The evolution of a household beverage
Monday, November 26th, 2012
Climate Change Stimulates Growth of Invasive “Super Weed”
Thursday, November 8th, 2012by Kristen Minogue
Tom Mozdzer explores a patch of invasive Phragmites in SERC's global change wetland.
Plants like this are called “jack-and-master” plants. Typically, the most competitive plants surpass their neighbors through one of two strategies. “Jack-of-all-trades” plants do moderately well under most scenarios. Their competitors will surpass them when conditions are good, but if the environment becomes stressful, the jack of all trades will grow better. “Master-of-some” plants do very well under only a few conditions, so if the environment shifts in their favor, they are certain to emerge victorious. But a few types—the jack-and-master plants—can use both tactics. And the invasive Phragmites is one of them.
Boaters: Beware of Hitchikers on the Hull
Thursday, October 11th, 2012by Ian Davidson
Propellor of a transient boat, veiled beneath a thick layer of biofouling. (Ian Davidson)
If several pounds of plant and animal material were attached to the underside of your car, slowing you down and increasing your fuel costs, you’d probably be concerned enough to remove it. The same applies to boats. But since boaters don’t have easy access to the undersides of their vessels, it can often be a surprise to discover large communities of organisms residing and hitchhiking on their hulls and running gear.
Nightly Oxygen Drops Deadly
for Chesapeake Oysters
Tuesday, September 25th, 2012
by Kristen Minogue
Slide of an oyster completely infected with Dermo.
Oysters in Chesapeake Bay face more dangers than overfishing and habitat loss. Over the last few decades they’ve also had to contend with crippling disease outbreaks. And according to marine ecologist Denise Breitburg, the wild day-night fluctuations in Bay waters aren’t helping.
Video: How A Flatworm Consumes Its Prey
Monday, September 10th, 2012Some of the most horrific images in high school biology textbooks depict parasitic tapeworms blocking the intestines of humans, or inside an unfortunate dog or cat. But not all flatworms are parasites, and their free-living cousins are capable of equally gruesome feats of nature. The slender flatworm Euplana gracilis consumes its victims by sucking out their insides, as displayed in the video above from benthic ecologist Dean Janiak.
It starts by wrapping its body around the dorsal (back) side of its prey–in this case, a shrimp-like amphipod. A massive struggle ensues until the amphipod is completely immobilized. Then the flatworm begins to feed. Sticking its tube-like pharynx through a segment of the amphipod, the flatworm consumes and digests its internals–a process that takes about half an hour. Once finished, it abandons the empty carcass and goes into a resting period until its next meal. On the outside, an amphipod that’s been eaten doesn’t look that different from a normal amphipod…except for the fact that it’s, well, dead.
Undersea Parasite Impregnates Crabs, Male and Female
Wednesday, September 5th, 2012by Monaca Noble
Infected crab. The sacs on its abdomen contain thousands of parasite larvae the crab will later release into the water.
The world is full of parasites that can force their hosts to do strange things. One such parasite lurks in Chesapeake Bay: an invasive barnacle that hijacks a mud crab’s reproductive system and impregnates it with parasite larvae—even if the crab is male.
The invasive parasite Loxothylacus panopaei (Loxo for short) is a type of barnacle, but looks and acts nothing like the typical barnacles growing on rocks along the shoreline. Loxo has a highly evolved life cycle, essentially custom-made for acting as a crab parasite. As a free-swimming larva, Loxo resembles a typical barnacle larva. A female larva infects a recently molted crab by burying into its shell. Once inside, she undergoes a series of changes and assumes control over the host crab, dictating major functions such as molting and reproduction.
Mangrove Tracking IX: To Catch a Tree Crab
Tuesday, July 31st, 2012by Megan Riley
A large adult male Aratus eating a juvenile of its species. (Megan Riley)
As adults, mangrove tree crabs (Aratus pisonii) tend to forage on fresh mangrove leaves in the canopy. As omnivores, they will also prey on nitrogen-rich insects, larvae, and even juveniles of their own species. However, it’s unclear how these organisms balance their nitrogen requirements and other nutritional demands. This summer I have focused my research on addressing this question. Specifically, I am investigating how their diet choices affect their overall health and ability to reproduce.
In order to perform this research, I first have to catch the Aratus! Despite the abundance of these animals in mangrove stands on the Indian River Lagoon, tree crab hunting is a tricky business. Over the course of the summer, I’ve learned a number of tips for trapping the elusive crustacean…
Mangrove Tracking VIII: Beneath the Waves
Tuesday, July 24th, 2012by Cora Johnston
The waters beneath mangroves are teeming with marine life, in part due to the refuge provided by the tangled complexity of their underwater roots. (Cora Johnston)
From salty branches to mucky roots, mangroves are teeming with life. Although many people recognize mangroves as spindly trees emerging right out of the water, it is under the water’s surface that mangroves really come alive for a marine ecologist like me. (That is also where you start to appreciate red mangroves’ apt name.)
Mangrove roots, both dangling from above (prop roots) and growing up from the sand (pneumatophores), not only mine for nutrients and allow for oxygen and carbon dioxide exchange for the plant; they also provide apparently crucial food and refuge for a stunning array of marine species. Fish, worms, crabs, shrimp, barnacles, and many other organisms take shelter among the roots – gluing right to the wood, hiding in crevices, and peering out through the maze. In such harsh intertidal conditions, where waves break, salt builds up, and the sun beats down, the shade and nooks formed by mangroves may be the key to survival for juvenile fish and crustaceans that will someday populate coral reefs and fishing hotspots farther offshore.
Over the coming months, I will be investigating how and why young fish and crustaceans use mangroves and marshes. By understanding the refuge provided by these very different coastal plants, I hope to better understand how the northward march of mangroves will influence the survival, abundance, and composition of marine species utilizing these now changing coastal nurseries.
Juvenile fish and crustaceans find safety in red mangrove roots during the early, vulnerable stages of their life. This young barracuda may be looking for a snack while hiding from larger predators. (Cora Johnston)
Even mangrove tree crabs that spend most of their time foraging in the canopy climb down to the safety of the mangrove roots to shed their old exoskeletons and harden their new ones. (Cora Johnston)
-Cora Johnston is a PhD student at the University of Maryland.
Mangrove Tracking VII: Just Another Day at the Office
Monday, July 16th, 2012by Nancy Shipley
Technician Lorae Simpson and intern Jake Bodart deep in the mangroves, assessing vegetation cover and substrate color. (Mayda Nathan)
It sometimes seems crazy to be climbing through mangrove stands and wading through large ponds to collect our data, but the sites we explore are chosen for a reason. That reason is two-fold: One, to ground truth satellite imagery so we can map historic and current mangrove distributions. Two, to document the plant communities in places dominated by mangroves, in places where mangrove encroachment is occurring, and in places where mangroves have not yet arrived.
By using satellite imagery from years past, we hope to determine how far mangrove communities have spread in the last few decades. To do this we have to first understand what individual plant species comprise the large areas of vegetation that we can see from the satellites.
That is where we come in, climbing through mangroves.
Mangrove Tracking VI: Attack of the Beetles
Thursday, July 5th, 2012by Jake Bodart
Beetle tunnel. This Scolytid beetle has burrowed into a mangrove seedling and lain its larvae inside. (Jake Bodart)
In the back of the Smithsonian Research Station here in Ft. Pierce, the mangrove team has built an artificial pond (we call it Lake Simpson) to raise mangrove seedlings that will be used in experiments. However, when we arrived here last month, we noticed that about half of the red mangroves were turning black and dying. It was unclear at first whether these mangroves were dying directly as a result of the artificial habitat (was our pond too hot? Too salty? Not salty enough?), or if the pond was somehow making the mangroves more susceptible to pest insects. We know from other studies that predation by insects can cause a large amount of propagule and seedling mortality.
Upon closer inspection, we decided insects were the culprit. The evidence of insect predation: small bore holes and little piles of frass (chewed up/excreted parts of the plant, a.k.a. insect poop). We decided to sacrifice the seedlings that were clearly infested, and dissect them to see if there were any insects inside.