Use of morphological characteristics for calculating individual biomass in the kelp Ecklonia cava

Abstract

Because kelp biomass contributes to the abundance and production of myriad animals and plants in coastal marine ecosystems, its measurement is critical to evaluating the impact of macroalgae on marine and aquatic habitats. We investigated the relationships among morphological characteristics to develop a non-destructive method for calculating Ecklonia cava biomass. Approximately 253 sporophytes of E. cava with various stipe size gradients were collected at five sites on a seasonal basis from November 2012 to August 2014. The relationships between morphological characteristics and individual weight were best fit by a non-linear regression equation, the sigmoidal regression equation. The length and diameter of the stipe, blade number, and total length accounted for more than 80% of the variation in individual weight. In particular, total length × blade number was highly correlated (r2 = 0.94) correlated with individual weight. The non-destructive method was 3.4–6.7 times faster than destructive sampling method. Considering the cost and time of fieldwork, stipe diameter and length are suitable for large-scale long-term monitoring. We recommend the use of the total length × blade number variable to improve the accuracy of plant biomass estimation in monitoring programs.