Figure 2. Study areas of the Galveston Bay system 

 showing bay areas, habitats, and locations of sampling 

 stations. 



greater than 3 m. Habitat depths (mean low 

 water) were determined from the U.S. Coast 

 and Geodetic Survey Nautical Chart No. 1282. 



Sampling frequency and the number of 

 sampling stations in each habitat and bay area 

 varied from year to year, and frequency also 

 varied within each year except 1963 (Table 1). 

 During a collection period, samples were taken 

 at all stations within a 2- or 3-day interval 

 except when adverse weather interrupted 

 sampling. All sampling was in daylight hours. 



Water samples or in situ measurements were 

 taken from the lower 0.3 m of the water 



column to determine temperature, salinity, dis- 

 solved organic nitrogen, total phosphorus and 

 dissolved oxygen. The techniques for meas- 

 uring each parameter are described by Pullen 

 and Trent (1969). 



ANALYSIS AND PRESENTATION OF DATA 



Data for each parameter were independently 

 related to habitat and bay area within each 

 year and are presented in statistical and/or 

 graphical form. Paired-comparison ^tests or 

 two-way analyses of variance were used for all 

 comparisons between habitats or bay areas. 

 Bay areas or habitats served as treatments and 

 dates of sampling as blocks. Mean values of a 

 given variable determined by combining data 

 from all stations within a particular habitat and 

 bay area for each collection were used as 

 observations for the statistical comparisons. 



WATER TEMPERATURE 



Water temperatures during this 4-year survey 

 ranged from 0.4° C to 36.0° C. The smallest 

 annual range was 23.4° C (9.0° C to 32.4° C) 

 in 1965 and the largest was 33.6° C (0.4° C to 

 34.0° C) in 1963. 



Comparison Between Habitats 



Comparisons of temperatures by habitat 

 within bay areas are shown in Table 2. Average 



Table 1.— Sampling frequency, type of information obtained, and the number of samples 

 taken by habitat and year in the Galveston Bay system, 1963-66. 



^aniplK.g /requ 



Weekly montKly Monthly 



1963 Peripheral 28 

 Ojje" water ZZ 

 Channel 6 



1964 Peripheral 11 

 Open water ZZ 

 Channel 9 



1965 Peripheral 15 

 Open water 16 

 Channel 5 



1966 Peripheral 17 

 Open water 17 

 Channel 6 



