tance to petroleum toxicosis. It was desirable to evaluate the harmful 

 effects of both chronic, sublethal levels of such toxicants on population 

 maintenance, and the more dramatic acute effects of short lethal ex- 

 posures. Eggs and larvae, especially those having a planktonic phase, 

 may be the stages in the life histories that are especially susceptible to 

 petroleum poisoning, or adversely affected by petroleums at levels 

 below those demonstrably affecting the adults. 



To determine the effects of petroleum oils on young stages of marine 

 animals, echinoderm and crustacean larvae have been used by the 

 University of Texas group at Port Aransas. Echinoderm eggs are es- 

 pecially suitable for observing deviations from normal development 

 because of the ease with which they can be collected, the large body 

 of embryological knowledge available concerning them, and their 

 demonstrated sensitivity to slight changes in the environmental media. 

 Experiments were successfully carried out on the effects of fuel oil 

 on the activity of gametes and the early development of sand dollar 

 eggs. Sperm activity, respiration, fertilization, cleavage and early de- 

 velopment to the pluteus stage were monitored. At a level of 0.6 ppm 

 of WSF of the API fuel oil, sperm motility ceased, fertilization was 

 hampered and abnormalities of cleavage became observable; at higher 

 concentrations, there was much mortality and gross retardation of 

 larval development. On the other hand, a crude oil — Kuwait — at even 

 high concentration, had little effect on development. 



Crustaceans studied were barnacles (eggs and nauplii) and crabs 

 (zoeae and megalops). Development of barnacle eggs was adversely 

 affected by No. 2 fuel oil (WSF) at concentrations of 0.3 ppm and 

 greater, especially in early stages. Older embryos were more tolerant; 

 hatching was slightly accelerated, but the larvae on emerging were 

 quickly killed. During short exposures it appears that the egg shell 

 affords some protection to the embryo. 



Considerable differences were discovered in the toxic effects of the 

 several oils investigated. Such differences are not unexpected because 

 of gross differences in composition of the oils. In order to evaluate the 

 relative toxicities of petroleum oils, short experiments of 1 and 24h 

 were carried out with barnacle larvae. An automated method was used 

 to count the larvae, live or dead, after exposure, and curves of effect vs 

 concentrations of water solubles of six oils, fractions of fuel oil and 

 thirteen aromatics were obtained (Fig. 4). Crude oils were toxic in 

 the order Venezuela > Kuwait > Alaska > Southern Louisiana. Of 

 oil derivatives, used crankcase oil was by far the most toxic (Table 10) . 

 Some especially toxic aromatics were 1 -methyl naphthalene, dimethyl 



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