NUTRIENT FLUX BETWEEN THE NUECES DELTAIC MARSH AND THE 

 NUECES ESTUARY ON THE TEXAS GULF COAST 



D.P. Wilcox, Institute of Applied Sciences, North Texas State University 



Denton, Texas 



W.M. Childress, Petra, Inc., Clear Creek Office Park 

 1213 N. Locust, Suite C, Denton, Texas 



ABSTRACT 



Movements of carbon, nitrogen, 

 and phosphorus in the surface wa- 

 ters between a tidal marsh and the 

 Nueces estuary, Nueces County, Tex- 

 as, were studied over an 8-month 

 period. Seasonal patterns in nu- 

 trient flux (where flux = flow x nu- 

 trient concentration) were evident 

 throughout the study period. Net 

 fluxes of virtually all nutrient pa- 

 rameters were directed out of the 

 marsh during the fall and winter, but 

 were directed into the marsh during 

 the spring. Combined net input of C, 

 N, and P in the spring and summer 

 ranged from 33 to 571 kg/hr. Tidal 

 fluctuations in the Nueces estuary 

 are normally low (0-60 cm). Based 

 on the study period the Nueces marsh 

 acts as a sink for those nutrients 

 transported by tides. 



INTRODUCTION 



Over the years there has been a 

 great deal of information gathered on 

 the relationship between an estuary 

 and its associated marshes. Several 

 processes such as nutrient exchange 

 and transport, detrital processing, 



primary production, fisheries dyna- 

 mics and estuarine hydrology have 

 been studied. Until recently most of 

 these studies have been born of pure- 

 ly academic curiosity. But now the 

 recent trend of reduction of fresh- 

 water inflows into these estuaries 

 for domestic and industrial use has 

 resulted in studies designed to as- 

 sess impacts of such actions on the 

 estuarine system as well as to help 

 in the development of overall manage- 

 ment strategies for these areas. 



One such study was recently per- 

 formed in the Nueces-Corpus Christi 

 Bay System located on the lower Tex- 

 as coast in order to provide informa- 

 tion needed to establish a management 

 scheme for freshwater releases from 

 an impoundment structure being built 

 on the Nueces River in south central 

 Texas. Part of this study involved 

 gathering data on nutrient flux in 

 the Nueces marsh, adjacent to the 

 Nueces River, in an effort to better 

 understand the role which the marsh 

 plays in processing nutrients (car- 

 bon, nitrogen, and phosphorus) that 

 are brought into the system. 



This paper is a presentation 

 of results derived from field data 



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