On the atoll of Takapoto, the temperature of the water ranges between 27 and 30°C and the salinity ranges between 37 and 39 psu. The temperature of the water is similar on Tikehau, but the salinity of the lagoon water is lower on this atoll: 35.5 psu on average (Charpy L. 1985). The difference between the salinity levels of these two lagoons, where the evaporation/precipitation balance is greater than 1, is due to the difference between the residence times of the oceanic waters in the lagoons, which have been calculated and found to be 4 years in the case of Takapoto (Magner & Wauthy 1976) and 0.5 years in that of Tikehau (Lenhardt 1991). In the other lagoons investigated so far, the salinity ranges between 35 and 37 psu, except on Taiaro, where it amounts to 43 psu. The latter lagoon is almost completely isolated from the open sea.

• The Polynesian atolls receive high levels of light energy, amounting on average (on the basis of monthly data) to between 35 and 55 Ei m^-2 / day^-1 (Tikehau). In the case of Takapoto, for example, we have the following daily energy curves.

• The percentage surface light energy penetrating to depths of 25m (this is the average depth of the Takapoto and Tikehau lagoons) is 10 % in the case of  Takapoto and 17 % in that of Tikehau. 

• In the case of other atoll lagoons, the light penetration has been measured using the Secchi disc method. When the lagoons were very shallow, the disc was placed horizontally.

• Apart from the hyper-saline lagoons (Taiaro et Takapoto), the salinity of the lagoon waters is fairly consistent (35-37 psu).

• The incident light energy reaches high levels throughout the Tuamotu archipelago and the light easily reaches the lagoon beds because of the transparency of the waters. A primary  production model based on the light energy received has shown that no photo-inhibitory processes occur, even at the times of day when the sunshine is the strongest (Charpy L. & Charpy-Roubaud CJ. 1990).