COUCH: DISEASES AND PARASITES OF PENAEID SHRIMPS 



Tl 



.V *^' 



M 



:^ 



CM 



Figure 41. — Electron micrograph of normal gill cuticle (arrow) and underlying osmoregulatory and 

 respiratory epithelium; note mitochondria (M), cell membranes (CM), hemolymph sinus (S), and cuticle 

 (C). X 14,400. 



exposed for brief periods. These authors also re- 

 ported that shrimp obtained from off Louisiana's 

 Southwest Pass had natural levels of only 4.6 ppb 

 mercury distributed as 64'7<^ in the muscle and 36*7^ 

 in the cuticle. 



Brown shrimp are active regulators of blood 

 chloride levels (ion regulators). Petrocelli et al. 

 (see footnote 12) found that exposure of brown 

 shrimp to mercury and to salinity changes re- 

 sulted in interference with the shrimp's ability to 

 adjust their internal ion levels to external salinity 

 changes. Therefore, mercury could prove to be det- 



rimental to penaeid shrimps if it were present in 

 form and amount enough to prevent their adjust- 

 ment to freshets or high saline conditions that 

 result from rapid changes in estuaries or tide- 

 lands. 



Chemotherapeutic Chemicals 



Certain inorganic and organic chemicals have 

 been tested for toxic effects in penaeid shrimps 

 because they are used routinely as chemo- 

 therapeutic agents in aquatic animal disease con- 

 trol. 



35 



