effects of various wavelengths of light on the 

 retinal pigment migrations in brown and white 

 shrimp. A Texas A&M University researcher 

 used the same facilities to study the effects of 

 certain mollusk predators and salinity ranges 

 on the brackish-water clam, Rangia cuneata. 



About half of the recirculating laboratory 

 facility has been taken over for research on 

 shrimp spawning and larval culture. For 

 these studies, we installed a 1 50,000-B.t.u, 

 (British thermal unit), salt-water heater and 

 various smaller temperature-regulating and 

 nutrient-flow control devices. 



Mechanically, we had a good year. One 

 forced shutdown of the recirculating system 

 was caused by city power failure, and two at 

 the lagoon laboratory by extremely low tides. 

 The intake end of one of the main pumps 

 at the lagoon laboratory has been extended 

 several feet to prevent future difficulty. 



During the year, 338,000 gal. of salt water 

 were added to the recirculating system. The 

 monthly rate of these additions is shown in 

 figure 44. 



The chemistry of the recirculating water is 

 more or less typical of that of waters of 

 such an enclosed system. The decomposition 

 products, ammonia and particularly phosphate 

 and nitrate, are very high. Fronn December 27 

 to March 15, only 4,000 gal. of water were 

 added to the system. The decline of salinity 

 during this period resulted from fresh-water 

 contamination, which was finally traced to a 

 leaking tapwater line. Beginning April 1, all 

 water in the system was replaced with "new" 

 water, and continued replacement has kept 

 levels of nitrate and phosphate relatively low. 



Kenneth T. Marvin, Supervisory Chemist 



30-, 

 25 



so- 

 ls- 



/ 



^-SALINITT %o * *" 



'^--... 



\ 



o~„ o>_ 



PHOSPHfiTE PHOSPHORUS lug Ot./L.) 



""-'>-»-»--._„-•' 



WATER ADDITION— 3 

 (1000 gol ) 



84 



16 



20 



48 



68 



Z- 



NITHATE-MTROGEN ( ng Ot. /L.) « 100 



' ^4 .1/ / ■> '• •■ '<L'''y \ .' NITRITE-NITROGEN (ug.Ot. 



^--«>.«^vV ^,i Lv Y-^v^----- — ^\ -.-. 



4 , o ,0-9 1 , , , ■ 1 





X- 





•-• — •-** 



■»-t , --- 



--.-•-•-• 



-I 1- ,,,...., 



JUL. AUG SEP OCT NOV DEC, JAN. FEB. MAR. APR MAY JUN. 

 1964 1965 



Figure 44. — Chemical composition (weekly averages) of water In the recirculating sea-water laboratory, 1964-65. 



47 



