Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Stuck in the middle with oysters and crabs

09.05.2014

North­eastern Uni­ver­sity ecol­o­gist David Kimbro claims to have watched a lot of TV growing up, par­tic­u­larly The Brady Bunch. “You could kind of get a flavor for how an episode was going to turn out based on how Jan or Peter were faring—you know, the middle kids,” said Kimbro, an assis­tant pro­fessor in the Depart­ment of Marine and Envi­ron­mental Sci­ences.

He and his colleagues—associate pro­fessor Jon Grabowski and assis­tant pro­fessor Ran­dall Hughes, ecology experts with labs at Northeastern’s Marine Sci­ence Center—think a sim­ilar pat­tern shows up in oyster reefs, where the behavior of the “middle child” in the predator-​​prey food chain plays a strong role in deter­mining how the reef as a whole will fare. New research from the team, pub­lished online on Tuesday in the journal Ecology Let­ters, gives that hunch even more support.


A mud­crab hiding from higher preda­tors in an oyster reef.

Photo cour­tesy of WFSU

The work com­pli­cates the evo­lu­tion of a par­a­digm that has per­vaded ecology since the 1960s, namely that the species at the top of the food web dic­tate the wel­fare of the entire system simply by eating.

For instance, obser­va­tions in the Aleutian Islands in the 1970s showed that when sea otters were doing well, the nearby kelp forests below the ocean’s sur­face also thrived. This was due, theory said, to the fact that the otters’ feeding pat­terns nat­u­rally man­aged the sea urchin pop­u­la­tion, which feeds on kelp.

... more about:
»Ecology »Marine »blood »excess »forests »healthy »sugar

Fast-​​forward four decades and one sees a large body of evi­dence indi­cating that preda­tors do more than eat; they frighten too. In the early 2000s, Grabowski showed that having a preda­tory fish scare the middle child has the same effect as pre­da­tion itself. Like­wise with the sea otters—just swim­ming around scares the urchins enough to send them into hiding and stop eating kelp.

These obser­va­tions have led researchers to assume that the mere pres­ence of a top predator is always ben­e­fi­cial for habi­tats like oys­ters and kelp, Kimbro said. “But,” he added, “we had a hunch that the lynch-​​pin of behavior is fickle. I mean, I can turn on a dime. Just ask my family when I miss snack time and the blood sugar gets low. So it seems log­ical that it’s not always going to be the same.”

To find out, the trio set up large exper­i­mental reefs along the eastern coast from Florida to North Car­olina. At each site, they cre­ated three reefs: one con­taining just oys­ters; one con­taining oys­ters and their imme­diate preda­tors, small mud crabs; and one con­taining the oys­ters and the mud crabs, as well as a scary fish and large crabs that feed on the mud crabs.

What they found sur­prised them. In North Car­olina, the pic­ture looked exactly the same as it did in the early 2000s, when Grabowski first did his behavior exper­i­ments. But from South Car­olina to Florida, the fear of pre­da­tion on the mud crabs actu­ally had a neg­a­tive effect on the overall reef.

That’s because as you move south­ward, the rivers that flow into the estu­aries become mud­dier. And more mud means the healthy, thriving oys­ters start to get buried under layers of sed­i­ment. When top preda­tors are scarce, the mud crabs feel safe enough to wander around the reef to eat baby oys­ters. As they do so, they kick off the river sed­i­ment and free the reef from being buried alive. It’s not so good for the reef when the crabs’ fear of being eaten pre­vents these reef strolls.

In North Car­olina, there isn’t as much sed­i­ment on the reef so the oys­ters don’t ben­efit from the mud crabs’ walking around.

Georgia and South Car­olina are super-​​sized value meals,” Kimbro said. “It’s like the whole system is on steroids. There’s so much oyster food there, the crabs are so well fed they don’t wander far from their home in the reef anyway.” So, fear isn’t as impor­tant there.

Each of these hyper-​​local sit­u­a­tions causes a unique effect, com­pli­cating the age-​​old story of the cer­tain ben­e­fits of top preda­tors. “This shows that you can’t just apply some­thing across the board,” Kimbro said. Instead, researchers have to con­sider each local com­mu­nity individually.

You could walk away from our paper thinking it’s just so com­pli­cated why even try,” Kimbro said. “But with careful exper­i­ments and so forth you can sep­a­rate a pre­dictable pat­tern from what seem­ingly is just noise.”

The research group’s next step is to see how the behavior of the middle preda­tors affect the ser­vices that oys­ters pro­vide to the urban coastal com­mu­ni­ties nearby. Oys­ters don’t just pro­vide a tasty food source for humans (and job secu­rity for the oyster fishers that col­lect them), but they also filter the water of excess nutri­ents, which can have neg­a­tive effects on the overall body of water.

As to whether the pat­tern Kimbro claims to have observed in The Brady Bunch is really true, well, “just go with it,” he said.

Casey Bayer | Eurek Alert!
Further information:
http://www.northeastern.edu/news/2014/05/stuck-in-the-middle-with-oysters-and-crabs/

Further reports about: Ecology Marine blood excess forests healthy sugar

More articles from Ecology, The Environment and Conservation:

nachricht Coorong Fish Hedge Their Bets for Survival
27.03.2015 | University of Adelaide

nachricht Greener Industry If Environmental Authorities Change Strategy
27.03.2015 | University of Gothenburg

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Experiment Provides the Best Look Yet at 'Warm Dense Matter' at Cores of Giant Planets

In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as...

Im Focus: Energy-autonomous and wireless monitoring protects marine gearboxes

The IPH presents a solution at HANNOVER MESSE 2015 to make ship traffic more reliable while decreasing the maintenance costs at the same time. In cooperation with project partners, the research institute from Hannover, Germany, has developed a sensor system which continuously monitors the condition of the marine gearbox, thus preventing breakdowns. Special feature: the monitoring system works wirelessly and energy-autonomously. The required electrical power is generated where it is needed – directly at the sensor.

As well as cars need to be certified regularly (in Germany by the TÜV – Technical Inspection Association), ships need to be inspected – if the powertrain stops...

Im Focus: 3-D satellite, GPS earthquake maps isolate impacts in real time

Method produced by UI researcher could improve reaction time to deadly, expensive quakes

When an earthquake hits, the faster first responders can get to an impacted area, the more likely infrastructure--and lives--can be saved.

Im Focus: Atlantic Ocean overturning found to slow down already today

The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe. 

Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been...

Im Focus: Robot inspects concrete garage floors and bridge roadways for damage

Because they are regularly subjected to heavy vehicle traffic, emissions, moisture and salt, above- and underground parking garages, as well as bridges, frequently experience large areas of corrosion. Most inspection systems to date have only been capable of inspecting smaller surface areas.

From April 13 to April 17 at the Hannover Messe (hall 2, exhibit booth C16), engineers from the Fraunhofer Institute for Nondestructive Testing IZFP will be...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference On Regenerative Medicine 2015: Registration And Abstract Submission Now Open

25.03.2015 | Event News

University presidents from all over the world meet in Hamburg

19.03.2015 | Event News

10. CeBiTec Symposium zum Big Data-Problem

17.03.2015 | Event News

 
Latest News

BLS Cargo orders 15 multisystem locomotives

30.03.2015 | Press release

Shark Tagged by NSU’s Guy Harvey Research Institute Is Apparently Enjoying Time in Warm, Tropical Waters

30.03.2015 | Life Sciences

Antarctic Ice Shelves Rapidly Thinning

30.03.2015 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>