Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New research on seaweeds shows it takes more than being flexible to survive crashing waves

11.05.2012
Bladed and branched algae adapted to strong wave conditions are able to reconfigure their shape and size

Seaweeds are important foundational species that are vital both as food and habitat to many aquatic and terrestrial shore organisms.


This image shows seaweeds reconfiguring in flow, viewed from downstream.
Credit: Courtesy of Patrick Martone, University
f British Columbia

Yet seaweeds that cling to rocky shores are continually at risk of being broken or dislodged from their holds by crashing waves with large hydrodynamic forces. So how do such seaweeds survive in intertidal zones? Do they have special properties that make them extremely flexible or particularly strong?

Patrick Martone (University of British Columbia) has spent a considerable amount of time standing on the shore watching big waves crash against intertidal rocks and wondering how the seaweeds—or anything else—manage to survive there.

"Many animals can run and hide when storms roll in and the waves increase," Martone observes. "But seaweeds don't have that option; they have to just hold on tight and face the waves head-on."

Indeed, the drift algae that pile up on the beach after a big storm suggest that not all algae are able to survive such onslaughts.

"So what is special about the ones that do survive?"

Previous research has found that one solution seaweeds have come up with is flexibility. Blades of seaweed may curl up and branches may collapse, thereby changing the shape of the seaweed and reducing drag as water velocity increases. But different seaweeds may utilize different strategies to effectively reduce drag, such that some may be better at changing shape and others at reducing size. Martone and colleagues from Stanford University and St. John Fisher College were interested in teasing apart some of these variables and published their findings recently in the American Journal of Botany.

By exploring the dynamics of size and shape changes of intertidal seaweeds at different rates of water flow, Martone and co-authors hoped to better understand the various strategies that have led to the morphological diversity in macroalgae seen along wave-swept shores.

The authors collected fronds from six different species of algae (four branched, two bladed) along the intertidal zone of the central Californian coast, placed them in a recirculating water flume, and measured the drag they experienced and the changes in shape and size they underwent under 15 different rates of water flow, ranging from 0 to 4 m/sec.

Interestingly, they found that while all six species of seaweed underwent severe reconfiguration as water velocity increased—thus limiting the drag they would otherwise experience if they were rigid—the two types of algae accomplished this in slightly different ways.

"Unbranched algae seem to be 'shape changers,' reducing drag primarily by folding and collapsing in flow," notes Martone. "Certain branched algae, on the other hand, are 'area reducers,' compensating for drag-prone shapes by reducing frond size through branch reorientation and compression. Thus, we demonstrate that flexibility acts in two distinct ways: permitting wave-swept algae to change shape and to reduce frond area projected into the flow."

Martone and colleagues also wanted to see how accurately responses at slow speeds of water flow could be extrapolated to what happens at higher speeds, such as what the seaweeds might be experiencing along the shore.

"Most structural engineers have it easy," Martone says. "Studying air flow around airplane wings or water flow around bridges is relatively straightforward, since these man-made structures are rigid and do not deform in flow. Seaweeds are more complicated because they are flexible. As flow speeds increase, flexible seaweeds re-orient and reconfigure, changing size and shape to reduce drag, making predictions much more difficult."

Indeed, the authors found that measurements extrapolated out from lower speeds did not always match those observed at higher speeds, making it tricky to predict what would happen at higher water velocities. Moreover, in the experimental water flume seaweeds may have more time to react to water speeds that are relatively slow compared with breaking waves—a condition whereby fast reaction times may be crucial for reconfiguring and reducing drag.

"Understanding how selection can act on the ability to change shape or the ability to reduce size in flow may give us insight into the morphological evolution of intertidal algae," summarizes Martone.

Martone concludes that further investigation is still needed to tease these features apart: "We have started building flexible models of branched and unbranched seaweeds in the lab to explore how precise changes in branching affect drag. We hope this work will help us better understand how waves have sculpted seaweeds over evolutionary time."

Patrick T. Martone, Laurie Kost, and Michael Boller. 2012. Drag reduction in wave-swept macroalgae: Alternative strategies and new predictions. American Journal of Botany 99(5): 806-815. DOI: 10.3732/ajb.1100541

The full article in the link mentioned is available for no charge for 30 days following the date of this summary at http://www.amjbot.org/content/99/5/806.full.pdf+html. After this date, reporters may contact Richard Hund at ajb@botany.org for a copy of the article.

The Botanical Society of America is a non-profit membership society with a mission to promote botany, the field of basic science dealing with the study and inquiry into the form, function, development, diversity, reproduction, evolution, and uses of plants and their interactions within the biosphere. It has published the American Journal of Botany for nearly 100 years. In 2009, the Special Libraries Association named the American Journal of Botany one of the Top 10 Most Influential Journals of the Century in the field of Biology and Medicine.

For further information, please contact the AJB staff at ajb@botany.org.

Richard Hund | EurekAlert!
Further information:
http://www.botany.org

More articles from Life Sciences:

nachricht Bolstering fat cells offers potential new leukemia treatment
17.10.2017 | McMaster University

nachricht Ocean atmosphere rife with microbes
17.10.2017 | King Abdullah University of Science & Technology (KAUST)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>