[en] Leaf mechanical traits are important to understand how aquatic plants fracture and deform when subjected to abiotic (currents or waves) or biotic (herbivory attack) mechanical forces. The likely occurrence of variation during leaf onto- geny in these traits may thus have implications for hydrodynamic performance and vulnerability to herbivory damage, and may be associated with changes in morphologic and chemical traits. Seagrasses, marine flowering plants, consist of shoot bundles holding several leaves with different developmental stages, in which outer older leaves protect inner younger leaves. In this study we examined the long-lived seagrass Posidonia oceanica to determine ontogenic variation in mechanical traits across leaf position within a shoot, representing different devel- opmental stages. Moreover, we investigated whether or not the collection proce- dure (classical uprooted shoot versus non-destructive shoot method: cutting the shoot without a portion of rhizome) and time span after collection influence mechanical measurements. Neither collection procedure nor time elapsed within 48 h of collection affected measurements of leaf biomechanical traits when sea- grass shoots were kept moist in dark cool conditions. Ontogenic variation in mechanical traits in P. oceanica leaves over intermediate and adult developmen- tal stages was observed: leaves weakened and lost stiffness with aging, while mid- aged leaves (the longest and thickest ones) were able to withstand higher break- ing forces. In addition, younger leaves had higher nitrogen content and lower fiber content than older leaves. The observed patterns may explain fine-scale within-shoot ecological processes of leaves at different developmental stages, such as leaf shedding and herbivory consumption in P. oceanica.
Akaike H. (1973) Information theory and an extension of the maximum likelihood principle. Proceedings 2nd International Symposium on Information Theory: 267–281.
Alcoverro T., Duarte C.M., Romero J. (1995) Annual growth dynamics of Posidonia oceanica: contribution of large-scale versus local factors to seasonality. Marine Ecology Progress Series, 120, 203–210.
Alcoverro T., Manzanera M., Romero J. (1998) Seasonal and age-dependent variability of Posidonia oceanica (L.) Delile photosynthetic parameters. Journal of Experimental Marine Biology and Ecology, 230, 1–13.
Bay D. (1984) A field study of the growth dynamics and productivity of Posidonia oceanica (L.) Delile in Calvi Bay, Corsica. Aquatic Botany, 20, 43–64.
Borum J. (1987) Dynamics of epiphyton on eelgrass (Zostera marina L.) leaves: relative roles of algal growth, herbivory, and substratum turnover. Limnology & Oceanography, 32, 986–992.
Bouma T.J., De Vries M.B., Low E., Peralta G., Tánczos I.C., van de Koppel J., Herman P.M.J. (2005) Trade-offs related to ecosystem engineering: a case study on stiffness of emerging macrophytes. Ecology, 86, 2187–2199.
Casola E., Scardi M., Mazzella L., Fresi E. (1987) Structure of the epiphytic community of Posidonia oceanica leaves in a shallow meadow. Marine Ecology, 8, 285–296.
Caye G., Rossignol M. (1983) Etude des variations saisonnières de la croissance des feuilles et des racines de Posidonia oceanica. Marine Biology, 75, 79–88.
Cebrián J., Duarte C.M., Marbà N., Enríquez S., Gallegos M., Olesen B. (1996) Herbivory on Posidonia oceanica: magnitude and variability in the Spanish Mediterranean. Marine Ecology Progress Series, 130, 147–155.
Coley P.D. (1980) Effects of leaf age and plant life history patterns on herbivory. Nature, 284, 545–546.
Duarte C.M. (1991) Allometric scaling of seagrass form and productivity. Marine Ecology Progress Series, 77, 289–300.
Garnier E., Shipley B., Roumet C., Laurent G. (2001) A standardized protocol for the determination of specific leaf area and leaf dry matter content. Functional Ecology, 15, 688–695.
Giraud G. (1979) Sur une méthode de mesure et de comptage des structures foliaires de Posidonia oceanica (Linnaeus) Delille. Bulletin Musée Histoire Naturelle Marseille, 39, 33–39.
Gobert S. (2002) Variations spatiale et temporelle de l'herbier à Posidonia oceanica (L.) Delile. PhD dissertation, Université de Liège, Belgium.
Gobert S., Lejeune P., Lepoint G., Bouquegneau J.-M. (2005) C, N, P concentrations and requirements of flowering Posidonia oceanica. Hydrobiologia, 533, 253–259.
Gobert S., Lejeune P., Chéry A., Boissery P., Sartoretto S., Andral B., Lepoint G., Richir J. (2012) Assessment of the ecological status of Posidonia oceanica meadow with a no destructive shoot method. Proceedings 3rd Mediterranean Seagrass Workshop 2012: 18 pp.
den Hartog C. (1970) The Sea-Grasses of the World. North-Holland Publishing Company, Amsterdam, London: 241 pp.
Hemminga M., Marbà N., Stapel J. (1999) Leaf nutrient resorption, leaf lifespan and the retention of nutrients in seagrass systems. Aquatic Botany, 65, 141–158.
Invers O., Pérez M., Romero J. (2002) Seasonal nitrogen speciation in temperate seagrass Posidonia oceanica (L.) Delile. Journal of Experimental Marine Biology and Ecology, 273, 219–240.
Koch E.W., Ackerman J.D., Verduin J., van Keulen M. (2006) Fluid dynamics in seagrass ecology—from molecules to ecosystems. In: Larkum A.W.D., Orth R.J., Duarte C.M. (Eds), Seagrasses: Biology, Ecology and Conservation. Springer, The Netherlands: 193–225.
Koehl M.A.R., Wainwright S.A. (1985) Biomechanics. In: Littler M.L., Littler D.S. (Eds), Handbook of Phycological Methods. Ecological Field Methods: Macroalgae. Cambridge University Press, Cambridge: 291–313.
Kuo J., den Hartog C. (2006) Seagrass morphology, anatomy, and ultrastructure. In: Larkum A.W.D., Orth R.J., Duarte C.M. (Eds), Seagrasses: Biology, Ecology and Conservation. Springer, The Netherlands: 51–87.
Kursar T.A., Coley P.D. (1991) Nitrogen content and expansion rate of young leaves of rain forest species: implications for herbivory. Biotropica, 23, 141–150.
Lepoint G., Defawe O., Gobert S., Dauby P., Bouquegneau J.-M. (2002) Experimental evidence for N recycling in the leaves of the seagrass Posidonia oceanica. Journal of Sea Research, 48, 173–179.
Mach K.J. (2009) Mechanical and biological consequences of repetitive loading: crack initiation and fatigue failure in the red macroalga Mazzaella. Journal of Experimental Biology, 212, 961–976.
Marbà N., Díaz-Almela E., Duarte C.M. (2014) Mediterranean seagrass (Posidonia oceanica) loss between 1842 and 2009. Biological Conservation, 176, 183–190.
Niklas K.J. (1992) Plant Biomechanics: An Engineering Approach to Plant Form and Function. University of Chicago Press, Chicago: 622.
Onoda Y., Westoby M., Adler P.B., Choong A.M., Clissold F.J., Cornelissen J.H., Díaz S., Dominy N.J., Elgart A., Enrico L., Fine P.V.A., Howard J.J., Jalili A., Kitajima K., Kurokawa H., McArthur C., Lucas P.W., Markesteijn L., Pérez-Harguindeguy N., Poorter L., Richards L., Santiago L.S., Sosinki E.E. Jr, Van Bael S.A., Warton D.I., Wright I.J., Wroght S.J., Yamashita N. (2011) Global patterns of leaf mechanical properties. Ecology Letters, 14, 301–312.
Ott J.A. (1980) Growth and production in Posidonia oceanica (L.) Delile. Marine Ecology, 1, 47–64.
Peirano A., Niccolai I., Mauro R., Bianchi C.N. (2001) Seasonal grazing and food preference of herbivores in a Posidonia oceanica meadow. Scientia Marina, 65, 367–374.
Prado P., Heck K. (2011) Seagrass selection by omnivorous and herbivorous consumers: determining factors. Marine Ecology Progress Series, 429, 45–55.
Prado P., Alcoverro T., Romero J. (2010) Influence of nutrients in the feeding ecology of seagrass (Posidonia oceanica L.) consumers: a stable isotopes approach. Marine Biology, 157, 715–724.
Puijalon S., Bouma T.J., Douady C.J., van Groenendael J., Anten N.P., Martel E., Bornette G. (2011) Plant resistance to mechanical stress: evidence of an avoidance–tolerance trade-off. New Phytologist, 191, 1141–1149.
R Core Team (2014) R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org/.
Read J., Stokes A. (2006) Plant biomechanics in an ecological context. American Journal of Botany, 93, 1546–1565.
Rueda J.L., Salas C., Marina P., Urra J. (2009) Herbivory on Zostera marina by the gastropod Smaragdia viridis. Aquatic Botany, 90, 253–260.
Rueda J.L., Salas C., Gofas S. (2011) Contrasting shell morphology, ingestion and grazing preferences in the neritid gastropod Smaragdia viridis (L.) on two seagrass species. Journal of Sea Research, 66, 222–230.
Sand-Jensen K. (1975) Biomass, net production and growth dynamics in an eelgrass (Zostera marina L.) population in Vellerup Vig, Denmark. Ophelia, 14, 185–201.
Sand-Jensen K., Jacobsen D., Duarte C.M. (1994) Herbivory and resulting plant damage. Oikos, 69, 545–549.
de los Santos C.B., Brun F.G., Onoda Y., Cambridge M.M., Bouma T.J., Vergara J.J., Pérez-Lloréns J.L. (2012) Leaf-fracture properties correlated with nutritional traits in nine Australian seagrass species: implications for susceptibility to herbivory. Marine Ecology Progress Series, 458, 89–102.
Van Soest P., Robertson J., Lewis B. (1991) Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. Journal of Dairy Sciences, 74, 3583–3597.
Vassallo P., Paoli C., Rovere A., Montefalcone M., Morri C., Bianchi C.N. (2013) The value of the seagrass Posidonia oceanica: a natural capital assessment. Marine Pollution Bulletin, 75, 157–167.
Vergés A., Becerro M.A., Alcoverro T., Romero J. (2007a) Variation in multiple traits of vegetative and reproductive seagrass tissues influences plant-herbivore interactions. Oecologia, 151, 675–686.
Vergés A., Becerro M.A., Alcoverro T., Romero J. (2007b) Experimental evidence of chemical deterrence against multiple herbivores in the seagrass Posidonia oceanica. Marine Ecology Progress Series, 343, 107–114.
