Kinetics of nitrate, ammonium, and urea uptake by four intertidal seaweeds from New Zealand
Phillips, JC and Hurd, CL, Kinetics of nitrate, ammonium, and urea uptake by four intertidal seaweeds from New Zealand, Journal of Phycology, 40, (3) pp. 534-545. ISSN 0022-3646 (2004) [Refereed Article]
The competitive ability for N uptake by four intertidal seaweeds, Stictosiphonia arbuscula (Harvey) King et Puttock, Apophlaea lyallii Hook. f. et Harvey, Scytothamnus australis Hook. f. et Harvey, and Xiphophora gladiata (Labillardière) Montagne ex Harvey, from New Zealand is described by the uptake kinetics for NO3−, NH4+, and urea. This is the first study to report uptake kinetics for N uptake by a range of southern hemisphere intertidal seaweeds in relation to season and zonation. Species growing at the highest shore positions had higher NO3− and urea uptake at both high and low concentrations and had unsaturable NH4+ uptake in both summer and winter. Although there was evidence of some feedback inhibition of Vmax for NO3− uptake by Stictosiphonia arbuscula growing at the lower vertical limits of its range, rates were high compared with species growing lower on the shore. Our results highlight the superior competitive ability for N uptake of certain high intertidal seaweeds, and consistent with our previous findings we can conclude that intertidal seaweeds in southeast New Zealand are adapted to maximizing N acquisition in a potentially N-limiting environment.