Temperature, conductivity, pH and dissolved oxygen during the experiment in Chwaka Bay (Unguja Island, Zanzibar Archipelago, Tanzania)

A Multiprobe 3430 (WTW GmbH) was utilized to measure temperature (TetraCon 925), conductivity (TetraCon 925), dissolved oxygen (FDO 925) and pH (SenTix 950). Each sensor was calibrated every two weeks. For the calibration of the conductivity sensor, it was immersed in a 0.01 M KCl: 1413μS standard. For the calibration of the dissolved oxygen sensor, its sponge was freshly moistened and kept in the cap during 15 minutes. After this time, it was calibrated with the measurement of the water saturated air in the cap. Lastly, for the calibration of the pH sensor, two solutions were used: pH: 4.01; +255 mV and pH: 7.00; +220 mV (25°C). The variables were measured in each experimental block at the peak of the low tide in the morning.