“…As a fast-growing, ephemeral species, Ulva has a higher nitrogen demand to reach maximum growth compared to Fucus, a slow growing species (Pederson and Borum, 1997 Ulva exhibits an ability to uptake in NH 4 + as an immediate surge, but ultimately, longer exposure to high levels of NH 4 + result in reduce uptake (Pederson and Borum, 1997). Rees et al (2007) showed significantly increased uptake rates of NH 4 + in Ulva intestinalis when NH 4 + concentrations increased, these uptake rates exceed those for NO 3 -, and the increased uptake of NH 4 + came with reduced uptake of NO 3 -. Fucus becomes saturated at NH 4 + and NO 3 -concentrations around 10-30 µM and the maximum uptake rates in this species are less than half of those observed in Ulva (Pederson and Borum, 1997).…”