Figure 4.

Smoothed time trajectories, obtained by means of GAM, of the log(Chla) vs log(TN) relationships for the 28 ecosystems representing the four regions. Open and filled symbols mark the start and end of the trajectories, and the annual means used for computing the trajectories are shown by gray dots. Linear relationships are shown for ecosystems (n = 10), where time departures from a stationary power relationship between Chla and TN was not significant (Table 3). A close-up of the trajectories for the different regions can be found in Figure S2.