COUCH: DISEASES AND PARASITES OF PENAEID SHRIMPS 



The major adverse effect o^ Leucothrix infesta- 

 tions on shrimp is probably interference with gas 

 diffusion across gill cuticle, particularly in mas- 

 sive infestations (Figure 7a, b). In experiments at 

 my laboratory, I found that pink shrimp when 

 exposed to various levels of an ethylene glycol- 

 containing waste in bioassay systems had heavy 



growths of L. mucor on their gills, whereas nonex- 

 posed, control shrimp had little or no growth on 

 their gills. Mortality of the exposed shrimp was 

 proportionate to the extent of growth of Leucothrix 

 on their gills. Indications from EM studies are that 

 the mucoid substance with which L. mucor at- 

 tached to gills may cover gills (Figure 9a, b) in 



r%. 







. . ^ '. 



0^ 



FIGURE 9. — a. Relationship of Leucothrix 

 mucor filaments to gill cuticle of pink 

 shrimp; note electron-opaque mucoid 

 substance (etrrow) at point of attachment 

 and adjacent to base of bacterium; no 

 penetration of cuticle occurs, demonstrat- 

 ing that the bacterium is not invaisive. 

 X 14,400. b. Higher magnification ofL. 

 mucor at point of attachment to gill; note 

 distribution of electron-dense mucoid 

 substance probably secreted by bacterium 

 (arrow); shrimp cuticle is intact, x 28,500. 



9b 



