**3.1 Sampling**

The study was based on samples collected at three sampling stations in the lagoon. North (**Figure 4**) is close to a narrow channel that interconnects the northernmost sealed bodies with a central portion of the lagoon; Center (**Figure 5**) is next to the channel that connects to the ocean; and South (**Figure 6**) is at the south end of the lagoon. Sampling occurred in the four seasons, fall (June 2011), winter (August 2011), spring (November 2011), and summer (February 2012). During the first sampling, in the fall, the channel was closed. It was open days before winter sampling and remained open for the remainder of the sampling period. For the diatoms analysis, sediment samples were collected at depths of 2 cm with a spatula, at the lagoon margin, and packed in glass pods for transport to the laboratory.
