Colombia
Figure 4 shows the surface temperature measured at 4 m of depth by the vessels thermograph, and Figures 5, a and b, show the profiles of the two hydrographical sections worked off Punta Guascama and Golfo de Tibuga respectively. The surface temperature is as during Survey II quite uniform with only a slight increase towards the shore. Inshore temperatures are 1 - 2°C lower than in April. The hydrographic profiles demonstrate the precense, as previously of a strong transition layer in 50 - 70 m of depth, somewhat higher and even more pronounced than in April. There is a marked difference in surface salinities with values as low as 28 ‰ off Golfo de Tibuga, an effect of high river runoffs in the rainy season. The oxygen content of the water is as previously above 1 ml/l down to about 200 m of depth.
Panama
Figure 6 shows the surface temperature and Figure 7, a and b the hydrographic profiles from the Gulf of Panama and the Gulf of Chiriqui respectively. The distribution of surface temperature is as found in May uniform over large areas, predominantly between 28 and 29°C with a slight increasing trend towards the shore. Also the temperature profiles are similar to those from May with 15°C bottom temperature at the edge of the shelf in the Panama Gulf and 17°C in the Gulf of Chiriqui. One can however, see that the rainy season affects the surface salinity with low values especially in the inner parts of the Gulf of Panama. Oxygen is above 1 ml/l in the bottom water over the whole shelf and this may have had a positive effect on fish distribution over the deeper parts.
Costa Rica
Figure 8 shows the surface temperature and Figure 9 the hydrographic profile off Golfo de Nicoya. The temperature of the surface is very uniform between 28.5 and 29.5°C with a slight tendency for increase towards the shore. The distributions of temperature, salinity and oxygen in the profile are very similar to those observed in the previous surveys, but with slightly lower salinity in inshore surface waters. Conditions of oxygen deficiency in Golfo Dulce remains as previously observed.
