STUDIES ON THE TIME COURSE OF SALINITY AND TEMPERATURE ADAPTATION 

 IN THE COMMERCIAL BROWN SHRIMP PENAEUS AZTECUS IVES 



I: INTRODUCTION 



This report is concerned primarily with the time course of 

 acclimation to salinity and temperature changes by brown shrimp 

 Penaeus aztecus Ives. Some observations on the behavioral re- 

 sponses of the shrimp in salinity media with deviated (modified) ion 

 concentrations are also reported. These experiments are a contin- 

 uation of studies originally begun in 1970 to determine salinity and 

 temperature relations in brown shrimp. The U.S. Army Corps of Engi- 

 neers sponsored the studies with the objective of understanding the 

 impact of engineering works on the ecology of coastal waters. 



During the last century estuaries have become vulnerable to in- 

 tensive human activities such as the enormous expansion of industries, 

 the installation of power plants, increased intensity of fishing and 

 recreational activities, and pollution. The Army Corps of Engineers 

 has been involved with flood control, intracoastal waterways and 

 other aids to navigation, construction of dams for diverting and 

 storing water, building levees and spillways, and filling and dredg- 

 ing operations. These operations naturally affect the normal pro- 

 cesses of the estuaries and alter the physical attributes like sa- 

 linity and temperature. Gunter (1967) described one instance in 

 Louisiana estuaries where some of these operations eliminated the 

 gradual transition from fresh water to salt water. Consequently, 

 the distribution pattern of local flora and fauna including large 

 animals and birds had undergone great changes. 



In addition to affecting natural salinity and temperature re- 

 gimes, dredging and filling alter the characteristics of the 



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