Root architecture of six tropical seagrass species, growing in three contrasting habitats in Indonesian waters

Direct measurements of root growth and productivity in the seagrasses Posidonia australis and P. sinuosa

“…Transplants grew more slowly than plants in established seagrass meadows on the basis of available data for maximum shoot productivity: 0.8 mg dry wt shoot 21 d 21 and 2 mg dry wt shoot 21 d 21 for the P. sinuosa and P. australis transplants in this study, compared to 2.5 mg dry wt shoot 21 d 21 and 4.6 mg dry wt shoot 21 d 21 in mature meadows of P. sinuosa and P. australis (Cambridge and Hocking 1997). Despite the high rates of root growth, root : shoot ratios still showed more biomass allocation to leaves than roots (Table 2), typical of the reduced root systems in seagrasses (Kiswara et al 2009). …”

“…An increase in lateral roots, however, may be accompanied by decreased growth of main root axes (Linkohr et al 2002). In the few studies of seagrass root development in relation to nutrient availability (Kiswara et al 2009), species in lownutrient environments directed growth to developing more extensive root systems, increasing the potential for accessing nutrients from the sediments and also changing the ratio of above-and below-ground biomass (Powell et al 1989;Perez et al 1994;Lee and Dunton 2000).The effect of season on root development in seagrasses has received limited attention, in contrast to the effect of season on leaf canopy and shoot growth. Studies that included changes in root biomass (Marbá et al 1996), root productivity, and linear root length over time (Cebrián et al.…”

“…Seagrasses take up nutrients mainly through the roots when concentrations of nutrients in the sediment are much higher than in the water column, and nutrient imbalances or limitation may also link to nutrient availability in the sediments. Rapid development of a strong root system for anchorage and nutrient uptake seems likely to enhance transplant success but little is known about root growth in any seagrasses, particularly their response to nutrient availability (Kiswara et al 2009). For species with extensive root systems that grow in subtidal environments, accurate sampling presents several difficulties, such as buoyant roots that are easily lost underwater and sediments that behave like a liquid when excavated.…”

Season and sediment nutrient additions affect root architecture in the temperate seagrasses Posidonia australis and P. sinuosa

“…After decades of debate as to whether seagrass roots are functional in nutrient acquisition or serve only to anchor the plants (Agami & Waisel 1986), there is now evidence for the importance of roots in acquiring nutrients for a number of seagrass species (Evrard et al 2005, Kilminster et al 2006, Vonk et al 2008. However, few studies have examined seagrass root systems beyond describing root architecture or estimating increases in root biomass over time (Marbà & Duarte 2001, Balestri & Lardicci 2006, Kiswara et al 2009). Small or faster-growing species are usually the subject of study (e.g.…”

“…Kiswara et al 2009). Similar to terrestrial grasses, seagrasses form extensive meadows via a network of underground rhizomes, but do so fully submerged in seawater.…”