*4.1. Physicochemical Parameters and SPM*

Summary statistics of the physicochemical parameters and SPM in the three sectors of the system, the stream, the inner part, and the inlets, is presented in Table 2; the detailed results per each sampling are given in Table A1. Salinity values exhibited significant spatial variation (Table 2) due to mixing of seawater and freshwater. Higher values were found at the inlets (A1 and A12) due to seawater intrusion. During both sampling periods, the western inlet exhibited higher values of salinity than the eastern, signifying that this part of the lagoon is more exposed to sea currents (Table A1). In fact, in the past, considerable amounts of sediments were transferred after strong and persistent northerly winds and sealed the inlet (a feature known as sediment plug), which was artificially re-opened in order to facilitate water circulation and fishing activities. Concerning the inner stations, surface salinity ranged from 8.6 to 17.6. Bottom salinity was higher than in surface layers (data not shown).

At the inlets, pH obtained typical values of seawater (7.9–8.3), whereas the values found at the inner part of lagoon and the stream were 7.5–8.3 and ≤ 7.5, respectively (Table 2).



Suspended Particulate Matter (SPM) concentrations were higher at the inlets than in the inner part of the lagoon (Table 2), due to the turbulent mixing of seawater and fresh/brackish water and the re-suspension of sediments. The lowest concentrations were found at the stream, station A13 (1.5 mg·L−<sup>1</sup> and 2 mg·L−<sup>1</sup> in the first and second sampling, respectively). Particles with diameter d > 8 μm accounted for 68 ± 14% (mean ± sd) of total SPM at the inlets, 64 ± 8% of SPM at the inner part of the lagoon, and 38 ± 23% at the stream.
