Browsing by Author "Vergara, J.J."
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- A comprehensive analysis of mechanical and morphological traits in temperate and tropical seagrass speciesPublication . de los Santos, Carmen B.; Onoda, Yusuke; Vergara, J.J.; Pérez-Lloréns, J. Lucas; Bouma, Tjeerd J.; La Nafie, Yayu A.; Cambridge, Marion L.; Brun, Fernando G.Knowledge of plant mechanical traits is important in understanding how plants resist abiotic and biotic forces and in explaining ecological strategies such as leaf lifespan. To date, these traits have not been systematically evaluated in seagrasses. We analysed mechanical (breaking force and tensile strength) and associated traits (thickness, width, length, fibre content, mass area, and lifespan) of leaves in 22 seagrass species (around one-third of all known seagrass species) to examine (1) the inter-specific variation of these traits in relation to growth form and bioregions, (2) the contribution of morphology to leaf breaking force, (3) how breaking force scales to leaf dimensions, and (4) how mechanical and structural traits correlate to leaf longevity. We also compared our seagrass dataset with terrestrial plant databases to examine similarities between them. Large variation in leaf breaking force was found among seagrass species but, on average, temperate species resisted higher forces than tropical species. Variation in leaf breaking force was largely explained by differences in leaf width rather than thickness, likely due to the benefits in leaf reconfiguration and light interception. Species of large dimensions (long leaves) typically had high leaf breaking force, plausibly to tolerate the drag forces they may experience, which are proportional to the leaf area. Leaves of long-lived species typically had high mass per leaf area and fibre content and they supported high breaking forces. Compared to terrestrial plants, seagrasses are short-lived species with moderately strong fibre-reinforced leaves, which probably evolved to withstand the hydrodynamic forces occurring in the sea, and in response to other environmental factors. Overall, our analysis provides new insights into the physical performance of seagrasses in the marine environment.
- Photosynthesis and growth in macroalgae: linking functional-form and power-scaling approachesPublication . de los Santos, Carmen B.; Pérez-Lloréns, J.L.; Vergara, J.J.Grouping species into functional-form groups and measuring directly their surface area to volume ratio are 2 common approaches to forecast primary production of marine macroalgae. A link between the functional-form model (FFM) and the power-scaling approach (PSA) for a wide variety of marine macroalgae has been attempted for the first time in the present work. To test both approaches, thalli of 44 species of marine benthic macroalgae were collected from intertidal zones adjacent to Cádiz Bay. Metabolic rates, tissue nutrient content, surface area to biomass ratio (SA/B) and specific growth rates were measured for these species. PSA slopes were close to 2/3 power for growth rate, while metabolic rates scaled very close to, or matched, 3/4 power. The FFM descriptive model provided similar results to the PSA when it was transformed to a numerical model through the SA/B ratio. Even though both models appear to be valid, the problems derived from species allocation into morphological groups, and other previous criticisms, make the direct use of SA/B ratios more suitable for representing primary production in macroalgal functional groups in numerical models of coastal ecosystems.