Biomass method for measuring productivity of Echlonia radiata, with the potential for adaptation to other large brown algae

Abstract

A solution is proposed to the problem of converting measurements of growth in length of E. radiata to estimates of biomass production. It is shown that production can be calculated by multiplying biomass per unit length (in the zone of maximum biomass) by the increase in length of the primary blade. E. radiata has three stages of growth: (i) a simple strap-shaped primary blade; (ii) secondary blades growing from the primary; (iii) tertiaries arising from the secondaries in the mature plant. Distribution of biomass was determined by making transverse cuts across the primary blade and weighing the segments together with all attached secondary and tertiary blades. Plants were divisible into a zone where secondaries and tertiaries were increasing in size, a zone where they were at maximum size, and a zone where they were eroding. Biomass per unit length was calculated for the zone of maximum biomass, and when multiplied by the growth in length gave a good estimate of biomass production. Adaptation of this method to other large brown algae of the Laminariales is proposed.