Above- and below-ground biomass and production by Thalassia testudinum in a tropical reef lagoon

Annual (1990–91) mean values of total biomass of Thalassia testudinum (Banks ex Konig) at three stations in different environments in a Caribbean reef lagoon varied between 573 g dry wt m −2 (±167 SD) in a back-reef station, 774 g dry wt m −2 (±167 SD) in a coastal fringe and 811 g dry wt m −2 (±131 SD) in a mid-lagoon station. Corresponding ratios of mean above-ground to total plant biomass were 4.8% (±1.0 SD), 6.7% (±1.6 SD) and 8.6 (±2.0 SD) respectively. Production of above- and below-ground plant parts were calculated using the annual mean formation rates for leaves. The calculated annual mean total plant production (excluding root production) was 426, 1015 and 1116 g dry wt m −2 at the back-reef, coastal and mid-lagoon station respectively. Above-ground production accounted for 60.8%, 60.3% and 65.9% of the total production at these respective stations. Unimodal seasonal variations in blade length synchronized with earlier reported fluctuations in blade growth, whereas variations in number of blades per shoot reflected seasonal variations in blade initiation rates.