QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online October 17, 2008
Journal of Experimental Biology 211, 3433-3441 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.020495

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Related articles in JEB Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Martone, P. T. Articles by Denny, M. W. Search for Related Content PubMed PubMed Citation Articles by Martone, P. T. Articles by Denny, M. W. Social Bookmarking                         What's this?

To break a coralline: mechanical constraints on the size and survival of a wave-swept seaweed

Patrick T. Martone^* and Mark W. Denny

Hopkins Marine Station of Stanford University, Pacific Grove, CA 93950, USA

^* Author for correspondence at present address: Department of Botany, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4 (e-mail: pmartone{at}interchange.ubc.ca)

Accepted 6 September 2008

Previous studies have hypothesized that wave-induced drag forces may constrain the size of intertidal organisms by dislodging or breaking organisms that exceed some critical dimension. In this study, we explored constraints on the size of the articulated coralline alga Calliarthron, which thrives in wave-exposed intertidal habitats. Its ability to survive depends critically upon its segmented morphology (calcified segments separated by flexible joints or `genicula'), which allows otherwise rigid fronds to bend and thereby reduce drag. However, bending also amplifies stress within genicula near the base of fronds. We quantified breakage of genicula in bending by applying known forces to fronds until they broke. Using a mathematical model, we demonstrate the mitigating effect of neighboring fronds on breakage and show that fronds growing within dense populations are no more likely to break in bending than in tension, suggesting that genicular morphology approaches an engineering optimum, possibly reflecting adaptation to hydrodynamic stress. We measured drag in a re-circulating water flume (0.23–3.6 m s^–1) and a gravity-accelerated water flume, which generates jets of water that mimic the impact of breaking waves (6–10 m s^–1). We used frond Reynolds number to extrapolate drag coefficients in the field and to predict water velocities necessary to break fronds of given sizes. Laboratory data successfully predicted frond sizes found in the field, suggesting that, although Calliarthron is well adapted to resist breakage, wave forces may ultimately limit the size of intertidal fronds.

Key words: adaptation, biomechanics, breaking stress, Calliarthron, decalcification, drag, flexibility, geniculum, intertidal, macroalgae, material properties

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

Related articles in JEB:

HOW CORALLINE SEAWEEDS WITHSTAND THE WAVES

Kathryn Phillips
JEB 2008 211: i. [Full Text]  

This article has been cited by other articles:

				K. J. Mach Mechanical and biological consequences of repetitive loading: crack initiation and fatigue failure in the red macroalga Mazzaella J. Exp. Biol., April 1, 2009; 212(7): 961 - 976. [Abstract] [Full Text] [PDF]

				K. Phillips HOW CORALLINE SEAWEEDS WITHSTAND THE WAVES J. Exp. Biol., November 1, 2008; 211(21): i - ii. [Full Text] [PDF]

				P. T. Martone and M. W. Denny To bend a coralline: effect of joint morphology on flexibility and stress amplification in an articulated calcified seaweed J. Exp. Biol., November 1, 2008; 211(21): 3421 - 3432. [Abstract] [Full Text] [PDF]