Nutrient uptake by leaves and roots of the seagrass Thalassia hemprichii in the Spermonde Archipelago, Indonesia

Abstract

The kinetics of ammonium and phosphate uptake by leaves and roots of the tropical seagrass Thalassia h e m p n c h~~ were investigated in laboratory experiments. Uptake in leaves of plants from 3 different locations, covering the range from coastal to oceanlc conditions In the region of investigation (Spermonde Archipelago, South Sulawesi. Indonesia), was compared. The leaves from all plant samples showed a clear capacity for both ammonlum and phosphate uptake. This uptake could be described by Michaelis-Menten kinetics. v,,,,, ranged between 32 and 37 pm01 g-' leaf dry weight h-' for ammonium and between 2.2 and 3.2 pm01 g-' leaf dry weight h-' for phosphate. K,,, ranged between 21 and 60 PM for ammonium and between 7.7 and 15 plvl for phosphate. There was no significant site difference in uptake characteristics (v,,,,,, and K,) of ammonium and phosphate. Uptake of ammonium and phosphate by roots was investigated with plants from the intermediate location. Barang Lompo, using an approach which allowed only calculation of uptake rates at natural pore water concentrations. Uptake rates were 22 and 1.0 pm01 g-' root dry w e~g h t h-' for ammonium and phosphate, respectively Calculations suggest that at all 3 locations uptake of ammonium and phosphate by roots was probably limited by the diffusion of nutrients in the sediment rather than by their uptake capacity. Evidence was found that the availability of nutrients in the root zone relative to the leaf zone affects the uptake affinity of the leaves. The role of roots versus leaves in supplying plant nutrients is discussed. We concluded that even in the tropics, where water column nutrient concentrations are often very low, leaves clearly have a significant ability for ammonium or phosphate uptake and that in some situations nutrient uptake by the leaves may even b e essential in meeting plant nutrient demands.

Growth dynamics of the seagrass, Zostera marina in Jindong Bay on the southern coast of Korea

“…However, some studies have suggested that seagrass leaves have higher nutrient affinities compared with roots to assimilate nutrients under lower concentrations (Pedersen et al 1997, Lee andDunton 1999). Thus, although there are significant differences in nutrient concentrations between the water column and sediment pore water, they equally contribute to seagrass nutrient acquisition for seagrass growth (Stapel et al 1996, Terrados and Williams 1997, Lee and Dunton 1999. Although seagrasses can utilize nitrogen from both the water column and sediments, reduced seagrass tissue N content has been reported during the periods of high growth (Stöcker 1980, Pirc and Wollenweber 1988, Pérez-Lloréns and Niell 1993.…”

Nutrient dynamics of seagrass ecosystems: 15N evidence for the importance of particulate organic matter and root systems

“…The relative importance of roots and leaves for nutrient uptake depends on a number of factors including the concentrations and availability in the water column and sediment reservoirs, and can vary from leaf-dominated to root uptake-dominated (Carignan & Kalff 1980). Foliar uptake supplies around 50% of the overall N requirement of Thalassia testudinum (Lee & Dunton 1999) and T. hemprichii (Stapel et al 1996); between 30 to 90% of the overall N requirement of Zostera marina (Iizumi & Hattori 1982, Short & McRoy 1984, Pedersen & Borum 1992, 1993; and in extreme cases, the complete N requirement of Phyllospadix torreyi (Terrados & Williams 1997). The assumed minor importance of roots for nutrient acqui-ABSTRACT: The availability of nitrogen in sediment phytodetritus to seagrass was investigated in 5 tropical species (Thalassia hemprichii, Halodule uninervis, H. pinifolia, Halophila ovalis/ovata and Syringodium isoetifolium) from Indonesia.…”

Determining interspecific interactions between the dominant macrophytes of tropical, atlantic seagrass meadows

“…Furthermore, nutrients may be taken up by seagrass leaves as they diffuse out of the sediments, which could impede detection of sediment vs. water column sources (for review see Hemminga et a l, 1991). Stapel et al (1996) found that the availability of nitrogen and phosphorus in the root and leaf zone affected the uptake affinity of the leaves of Thalassia hemprichii, and that leaf uptake may be essential for growth even in oligotrophic waters.…”

“…Stapel et al (1996) found that the availability of nitrogen and phosphorus in the root and leaf zone affected the uptake affinity of the leaves of Thalassia hemprichii, and that leaf uptake may be essential for growth even in oligotropMc waters.…”

“…Patriquin, 1972;Gallegos et a i, 1994;van Tussenbroek, 1995), resource acquisition strategies (e.g. Patriquin, 1972;Larkum and lames, 1996;Stapel et al, 1996), reproductive strategies (e.g. Lewis and Phillips, 1980;Johnson and Williams, 1982;Cox and Tomlinson, 1988;Witz and Dawes, 1995) population structures (e.g.…”