Table 1.- Development of Palaemonetes larvae exposed to polyethylene oxide solutions (Mean with 



standard deviation). 



natural waters, but it may appear in tank culture 

 operations. 



First-day mortalities were significant only in 

 the higher treatment concentrations when P. 

 pugio larvae were reared in covered plastic boxes 

 (Figure Ic). These deaths apparently were the 

 result of oxygen depletion in the culture water 

 caused by overfeeding and the relatively high 

 biochemical oxygen demand of the polymer solu- 

 tions (Wade 1973). Other mortalities totaled only 

 5.6 and 6.9% in the 50- and 100-wppm concentra- 

 tions, respectively, after the first day. 



In all but one instance, larvae in the polymer 

 solutions exhibited a marked reduction in other 

 mortalities (i.e., "natural" deaths) over the con- 

 trols. Thus, in addition to eliminating stranding, 

 the polyethylene oxide somehow acted to reduce 

 other causes of mortality. The reason for this 

 beneficial effect is unknown, but it is unlikely to be 

 nutritional since, in vertebrates at least, the 

 polymer is poorly absorbed from the gut (Smyth et 

 al. 1970). Further study is needed to examine the 

 reasons for this effect and to evaluate the poten- 

 tial of polyethylene oxide for use in mariculture 

 operations. 



Acknowledgments 



We thank J. Williams for assistance in the 

 laboratory and E. Myatt for preparing the figure. 



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Paul A. Sandifer 



Marine Resources Research Institute 

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 Charleston, SC 29^12 



College of Engineering 

 Clemson University 

 Clemson, SC 29631 



Paul B. Zielinski 

 Walter E. Castro 



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