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 Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen

nachricht Plenty of habitat for bears in Europe
24.07.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

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: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Quantum bugs, meet your new swatter

20.08.2018 | Information Technology

A novel synthetic antibody enables conditional “protein knockdown” in vertebrates

20.08.2018 | Life Sciences

Metamolds: Molding a mold

20.08.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>