Biomass, net production and growth dynamics in an eelgrass (Zostera marina L.) population in Vellerup Vig, Denmark

Abstract

The biomass of an eelgrass population in Vellerup Vig, Denmark showed a unimodal seasonal pattern, March to October 1974, with the peak in August. Biomass of leaves and flowering turions was quadrupled, biomass of rhizomes doubled from March to August. The maximum total biomass was 443 g dry wt/m2. The leaf production was determined by a leaf marking technique, which also made it possible to estimate the rhizome production. In the period 9 April to 16 October 1974, the leaf production was 856 g dry wt/m2 and the rhizome production 241 g dry wt/m2 , which made a total of 1097 g dry wt/m2. The dominance of leaf production, though leaf and rhizome biomass were of the same magnitude, arose from a higher turnover rate of leaves (1.8 % per day) than of rhizomes (0.7 % per day). On the average a new leaf was produced on each turion every 14 days. The lifetime of the leaves was about 56 days. Total radiation and not temperature seemed to control leaf production. The maximum leaf production rate of 7.9 g dry wt/m2 per day in mid-June coincided with maximum radiation. The total production was 3.8 times the net increase of total biomass and 2.5 times the maximum total biomass.