title: VARIATION IN ANATOMICAL AND MATERIAL PROPERTIES EXPLAINS DIFFERENCES IN HYDRODYNAMIC PERFORMANCES OF FOLIOSE RED MACROALGAE (RHODOPHYTA)(1).
abstract: Over the last two decades, many studies on functional morphology have suggested that material properties of seaweed tissues may influence their fitness. Because hydrodynamic forces are likely the largest source of mortality for seaweeds in high wave energy environments, tissues with material properties that behave favorably in these environments are likely to be selected for. However, it is very difficult to disentangle the effects of materials properties on seaweed performance because size, shape, and habitat also influence mechanical and hydrodynamic performance. In this study, anatomical and material properties of 16 species of foliose red macroalgae were determined, and their effects on hydrodynamic performance were measured in laboratory experiments holding size and shape constant. We determined that increased blade thickness (primarily caused by the addition of medullary tissue) results in higher flexural stiffness (EI), which inhibits the seaweed's ability to reconfigure in flowing water and thereby increases drag. However, this increase is concurrent with an increase in the force required to break tissue, possibly offsetting any risk of failure. Additionally, while increased nonpigmented medullary cells may pose a higher metabolic cost to the seaweed, decreased reconfiguration causes thicker tissues to expose more photosynthetic surface area incident to ambient light in flowing water, potentially ameliorating the metabolic cost of producing these cells. Material properties can result in differential performance of morphologically similar species. Future studies on ecomechanics of seaweeds in wave-swept coastal habitats should consider the interaction of multiple trade-offs.
authors.affiliation: Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4Friday Harbor Laboratories, Department of Biology, University of Washington, Friday Harbor, Washington 98250, USADepartment of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4Department of Botany, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4.
authors.forename: Kyle W
authors.initials: KW
authors.lastname: Demes
authors.affiliation: Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4Friday Harbor Laboratories, Department of Biology, University of Washington, Friday Harbor, Washington 98250, USADepartment of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4Department of Botany, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4.
authors.forename: Emily
authors.initials: E
authors.lastname: Carrington
authors.affiliation: Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4Friday Harbor Laboratories, Department of Biology, University of Washington, Friday Harbor, Washington 98250, USADepartment of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4Department of Botany, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4.
authors.forename: John
authors.initials: J
authors.lastname: Gosline
authors.affiliation: Department of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4Friday Harbor Laboratories, Department of Biology, University of Washington, Friday Harbor, Washington 98250, USADepartment of Zoology, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4Department of Botany, University of British Columbia, 6270 University Blvd. Vancouver, B.C., Canada V6T 1Z4.
authors.forename: Patrick T
authors.initials: PT
authors.lastname: Martone
keywords: Rhodophyta; biomechanics; blade; cortex; flexural stiffness; medulla