from November to December. Temperatures 

 fluctuated over a greater range in the fall and 

 winter than in the spring and summer, prob- 

 ably because cold fronts frequently move over 

 the system during fall and winter. 



SALINITY 



Salinities in the Galveston Bay system 

 ranged from 36.6%oin the Houston Ship Chan- 

 nel in Lower Galveston Bay during 1963 to 

 0.1%o in Trinity Bay in 1965 and 1966. The 

 lowest and highest salinities observed over the 

 entire area for each year were 0.4 and 36.6%o in 

 1963,0.3 and 33.3%^ in 1964,0.1 and 36.0%.. in 

 1965, and 0.1 and 34.39« in 1966. 



Comparison Between Habitats 



In most bay areas and during most years, 

 mean salinity was slightly higher in the open 

 water than in the peripheral habitat and consid- 

 erably higher in the channel than in the other 

 two habitats (Table 3, Figure 4). These differ- 



Table 3.— Comparisons of annual mean bottom salini- 

 ties between habitats within each bay area in the 

 Galveston Bay system, 1963-66. 



Figure 4. Mean bottom salinity by date and habitat 

 within each bay area of the Galveston Bay system, 

 1963-66. 



ences in salinity between habitats were highly 

 significant except for East Bay in 1965. The 

 greatest difference between habitats was in the 

 three western bay areas, which are under the 

 direct influence of the Houston Ship Channel. 



Comparison Between Bay Areas 



Salinities were significantly different be- 

 tween bay areas within each habitat during 

 each year (Table 4). SaUnities were lowest in 

 Trinity Bay and highest in Lower Galveston 

 Bay. A progressive increase in salinity from the 

 upper bays to the Gulf was evident in all 

 habitats each year, with the exception of East 



Table 4.— Comparisons of annual mean bottom salini- 

 ties between bay areas within each habitat in the 

 Galveston Bay system, 1963-66 



Calvesi 



Mid- L 



Galveston Gai 



of 

 freedom 



1963 

 1964 

 1965 



1966 

 1963 



17.9 

 16-4 



16.7 

 10- 5 

 19.4 



19ti4 iH.5 



1965 17.5 



1966 10.5 



1963 22 9 



1964 23.0 



1965 15 9 



1966 16.9 



13.0 



12.6 

 7-9 

 5.4 

 15.3 

 15- 7 

 11.8 

 7-3 



18. I 

 17.9 

 15.5 

 10.9 

 18.8 

 19.5 

 13.9 

 11.6 

 25.0 

 24 I 

 19.0 

 20. 2 



15 4 

 9.8 

 19-9 

 19-9 

 17 8 

 12. 5 

 27.0 

 26.0 

 21 .7 

 22. 8 



22.7 

 21.4 

 16- 7 

 12.5 

 24.9 

 24.6 

 23.5 

 18. 7 

 29.4 

 28.8 

 23.6 

 25, 8 



4. 92 

 4. 52 

 4. I 12 

 4. 96 

 4. 84 

 4. 52 

 4, 60 

 4. 104 

 3. 69 

 3. 39 

 3, 72 

 3. 75 



29.8** 

 19. 2** 

 63. 5M 

 38. O** 

 35. 5** 

 34. !•• 

 39. 9»* 

 78. I** 

 25.4*» 

 B.6** 

 15. O** 

 32. 9** 



** Significance level = 1%. 



