^f^~^^=5:^A 1963-1966 



■"" ^ SAL (%o) 



Figure 7. Annual isohalines and the average isohaline 

 based on 4 years of data, 1963-66. 



in the western portion of the system em- 

 phasized the importance of Bolivar Roads Tidal 

 Pass and the Houston Ship Channel as an ex- 

 change mechanism for bay and Gulf waters. 

 Rollover Pass had little influence on the sys- 

 tem, except in East Bay in the immediate 

 vicinity of the pass. 



DISSOLVED ORGANIC NITROGEN 



Concentrations of dissolved organic nitrogen 

 in the Galveston Bay system varied from 1 /Lig 

 at/liter to 300 /xg at/liter. Both extremes were 

 recorded in Upper Galveston Bay. The range in 

 values in the bay system for each year that 

 nitrogen was sampled were 10 to 251 fxg 

 at/liter in 1964, 1 to 300 ^lg at/liter in 1965, 

 and 6 to 200 jUg at/liter in 1966. 



Comparison Between Habitats 



Concentrations of nitrogen differed signif- 

 icantly between habitats in Lower Galveston, 

 Upper Galveston, and East Bays in 1965 and in 

 Lower Galveston Bay in 1966 (Table 5, Figure 

 8). The greatest concentration of nitrogen was 

 in the channel habitat in Upper Galveston and 

 East Bays in 1965, whereas the peripheral 

 habitat of Lower Galveston Bay had the 

 greatest concentration of nitrogen in 1965 and 

 1966. 



Table 5.— Comparisons of annual mean concentrations 

 of dissolved organic nitrogen between habitats within 

 each bay area in the Galveston Bay system, 1964-66. 



Bay 

 area 



Habitats compa 

 nitrogen \ 



Upper 

 Galveston 



Mid- 

 Galxeston 



Lower 

 Galveston 



1964 

 1965 

 1966 

 1^64 

 1965 

 1966 

 1964 

 1965 

 1966 

 1964 

 1965 

 1966 



1964 

 1965 

 1966 



2, IS 

 2. 50 



0.07 

 34.04** 



106 

 129 



24 

 2. IS 

 2. 40 



23 



2. 18 



2. 38 



0. 18 



1.71 



0,83 



1.82 



0.92 



4. 16** 



0.62 



0.B7 

 0.64 



0.55 

 6.55** 



** Significance level = 



UPPER GALVESTON BAY 

 MI0-GALVE5TON BAY 



Figure 8. Mean concentrations of dissolved organic 

 nitrogen by date and habitat within each bay area of 

 the Galveston Bay system, 1964-66. 



