Temperature- and light-dependent growth and metabolism of the invasive red algae<i>Gracilaria vermiculophylla</i>– a comparison with two native macroalgae

Abstract

We conducted two temperature experiments to investigate the invasion success of the coarsely branched red algae, Gracilaria vermiculophylla. Our working hypothesis was that the coarsely branched G. vermiculophylla, with well-known broad environmental tolerances, would have physiological traits in-between the typical r and K strategies. A factorial experiment provided light-dependent models of growth rate at six temperatures, with maximum growth of 0.045 day-1 at 20°C. Light-saturated growth and maximum light utilization efficiency both displayed a bell-shaped temperature dependency, with optima at 21°C and 23°C respectively. The minimum light required to maintain growth was low (