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A comprehensive analysis of mechanical and morphological traits in temperate and tropical seagrass species
De los Santos C.
Marine Ecology Progress Series
Q1Abstract
Knowledge of plant mechanical traits is important in understanding how plants resistabiotic 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 seagrassspecies) to examine (1) the inter-specific variation of these traits in relation to growth form andbioregions, (2) the contribution of morphology to leaf breaking force, (3) how breaking force scalesto leaf dimensions, and (4) how mechanical and structural traits correlate to leaf longevity. We alsocompared our seagrass dataset with terrestrial plant databases to examine similarities betweenthem. 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 waslargely explained by differences in leaf width rather than thickness, likely due to the benefits inleaf reconfiguration and light interception. Species of large dimensions (long leaves) typically hadhigh leaf breaking force, plausibly to tolerate the drag forces they may experience, which are proportionalto the leaf area. Leaves of long-lived species typically had high mass per leaf area andfibre content and they supported high breaking forces. Compared to terrestrial plants, seagrassesare short-lived species with moderately strong fibre-reinforced leaves, which probably evolved towithstand the hydrodynamic forces occurring in the sea, and in response to other environmentalfactors. Overall, our analysis provides new insights into the physical performance of seagrasses inthe marine environment.