A Hydrographic Survey of the Galveston Bay System, Texas, 



1963-66 ^ 



By 



E. J. PULLEN, W. L. TRENT, and G. B. ADAMS 



National Marine Fisheries Service Biological Laboratory 

 Galveston, Texas 77550 



ABSTRACT 



Water temperature and salinity data, taken during 1963-66, and dissolved organic 

 nitrogen, total phosphorus, and dissolved oxygen data taken during 1964-66 from 

 Galveston Bay, Texas were analyzed by area and habitat (depth strata). 



Temperatures ranged from 0.4° C to 36.0° C during the study and averaged slightly 

 higher in the peripheral than the open-water or channel habitat. Between years, water 

 temperature averages varied as much as 7°C between coldest months, and 3°C between 

 warmest months. 



Salinities ranged from 0.1to36.6%o and increased from the peripheral to the channel 

 habitats. Gradients of increasing salinities occurred from east to west and north to south 

 in the system. Salinities decreased from 1963 to 1966 with the smallest difference 

 between years occurring in March and April and the greatest difference between years in 

 May and June. Minimum salinities always occurred during periods of high stream 

 discharge in the winter and spring and maximum salinities during periods of low stream 

 discharge in the late summer and fall. 



Dissolved organic nitrogen concentrations ranged from 1 to 300 jug at /liter. 

 Nitrogen concentrations decreased from the upper to the lower bays. Nitrogen values 

 were similar seasonally and between years. High river flow was correlated with an increase 

 of nitrogen in the lower bay areas. 



Total phosphorus concentrations ranged from 0.1 to 47.5 ^ig at /liter. Phosphorus 

 concentrations diminished from upper to lower bays, and from west to east in the system. 

 Seasonal concentrations of phosphorus were similar from 1964 through the spring of 

 1966. In June 1966, concentrations increased, reaching an all years' maximum in the fall. 

 River discharge was not correlated to phosphorus concentrations, although nitrogen and 

 phosphorus values were positively correlated. 



Dissolved oxygen concentrations ranged from 0.2 to 13.6 ml/liter. Lowest oxygen 

 concentrations were in the channels and highest and similar concentrations were in the 

 peripheral and open-water habitats. Oxygen values were inversely correlated with water 

 temperatures. 



INTRODUCTION in many estuaries and lagoons along the U.S. 



coast. Alterations caused by the construction 



Degradation or destruction of estuarine of channels, dikes, and bulkheads; the dis- 



habitats by municipal, industrial, agricultural, charge, of pollutants; and the reduction of 



and recreational expansion is a major problem freshwater flows change the hydrological char- 



I Contrihution No. 31 5, National Marine lislUTJus Serv ice 

 liiolO):ical laboratory, (lalveston. Texas 77550. 



