Biomass distribution and leaf nutrient concentrations and resorption of Thalassia hemprichii at Inhaca Island, Mozambique

Abstract

Biomass and nutrients (C, N and P) of the seagrass Thalassia hemprichii were compared for the Northern Bay (NB) and Southern Bay (SB) of Inhaca Island, southern Mozambique. T. hemprichii is one of the most dominant seagrass species in the Indian Ocean, although still poorly documented in Africa. Its mean biomass varied between 787.4 ± 233.8gDWm−2 and 1876.8 ± 389.4gDWm−2 for NB and SB, respectively. For the associated seagrass species, Cymodocea rotundata, Halodule wrightii, Halophila ovalis and Zostera capensis, they corresponded up to 8.8% of the T. hemprichii biomass. Leaf nutrient concentrations showed a clear gradual decrease with age. This varied from 3.03% to 1.7% for N, 0.25% to 0.07% for P in NB and from 3.3% to 1.7% for N, 0.27% to 0.1% for P in SB. Mean C:N:P ratios, normalised for biomass, were 545:35:1 and 509:35:1 for NB and SB, respectively. The leaf resorption efficiencies, were 9.5% and 63.9% for nitrogen and 44.4% and 63.2% for phosphorus in NB and SB, respectively.