Meeting Abstract

S4.5  Monday, Jan. 4  Reconfiguration and the biomechanics of flexible wave-swept macroalgae BOLLER, M.L.; St. John Fisher College mboller@sjfc.edu

The hydrodynamic forces experienced by wave-swept intertidal macroalgae are influenced by reconfiguration, i.e. the change in size and shape of the organism projected into the flow. These changes result from the forces generated by that flow and modify the change in force associated with a change in flow velocity. Reconfiguration mollifies the effect of increased flow velocity, allowing organisms to be larger at low, benign flows and smaller with lower potential for dislodgement at high and potentially damaging drags. Reconfiguration influences the hydrodynamic performance (measured as the ability to resist damage with increased flow velocity) and has been said to be a prerequisite for macroalgal survival in the wave-swept intertidal zone. Here I will present my and my collaborators’ work exploring the mechanisms of reconfiguration, our ability to predict drag and reconfiguration in macroalgae, and some of the theoretical implications of reconfiguration on the evolution of macroalgae. A model that isolates the separate mechanisms of change in size (area projected into the flow) and shape (drag coefficient) in reconfiguration was developed and refined. With this model, mechanistic predictions of drag at high field velocities are possible and have been tested under controlled conditions. Further, the isolation of size and shape effects has revealed different potential mechanical strategies among algae. Some species may be more effective at reducing size, while others shape, with both strategies achieving similar hydrodynamic performance. These emergent properties of flexibility may have influenced the evolution of intertidal macroalgae, contributing to the wide range of morphologies that are successful in the intertidal zone.