Figure 3: Examples of NH4+ uptake experiments in the laboratory.

Decrease of NH4+ concentrations in the incubation water due to NH4+ uptake by (a,b) the macroalga Dictyota menstrualis (from 5ām depth) and (c,d) the benthic cyanobacterium Lyngbya majuscula (from 20ām depth). The species were incubated at low (left column) and at high (right column) initial NH4+ concentrations. Error bars represent s.d. of the mean (nā=ā9). NH4+ uptake experiments of the other species are shown in Supplementary Figs S1 and S2.