short exposure periods (fig. 9). Growth and fecundity are re- 

 duced at lower levels, 0.6 and 0.2 ppm, respectively. When 

 adults are exposed to low levels of the oil for 1 month, there is 

 high mortality among the young; more than 70 percent in 5 

 weeks (fig. 10). When constituents of the oil were tested, it was 

 found that certain combinations, (e.g., naphthalene and benzene) 

 were more toxic than single compounds, suggesting synergistic 

 effects. 



In conjunction with CEPEX, experiments were made on 

 petroleum hydrocarbons by adding a dispersion of Prudhoe 

 crude oil to a quarter-scale enclosure (about 60,000 1). The 

 results show that the concentration of the different aromatics in 

 water, zooplankton, oysters, and bottom sediments decreased at 

 an exponential rate, because of evaporation, photochemical oxi- 

 dation, microbial degradation, and sedimentation (fig. 11). 



Results of studies investigating the effects of pollutants on 

 embryonic and larval development, growth, and bioenergetics of 

 marine invertebrates and fish show that the embryo-larval stages 

 of the fish, Fundulus heteroclitus, were moderately tolerant to 

 water-soluble fractions (WSF) of No. 2 fuel oil, showing an 

 LC 50 of about 1.5 ppm total hydrocarbons. The early embry- 

 onic stages were more sensitive to oil than were later embryonic 

 and larval stages. The instantaneous uptake rate and release 

 rate of C 1 '-naphthalene were highest in 2-day-old embryos and 

 decreased in a linear fashion as development progressed. Lar- 

 vae hatching from hydrocarbon-exposed embryos were smaller 

 than controls, and slightly stressful temperatures and salinities 

 greatly increased the sensitivity of these fish embryos to hydro- 



carbon exposure. 



Larvae of the mud crab, Rhithropanopeus harrisii, were ex- 

 posed continuously during development to naphthalene or phen- 

 anthrene at different combinations of temperature and salinity. 

 Phenanthrene was substantially more toxic than naphthalene. 

 Slightly stressful temperature/salinity regimes increased larval 

 sensitivity to naphthalene and phenanthrene as shown by de- 

 creased survival to metamorphosis, increased duration of larval 

 development, increased respiratory rates of exposed larvae, and 

 increased sensitivity to acute salinity stress. The results indicate 

 that sublethal hydrocarbon stress shunted assimilated energy 

 away from growth processes to maintenance functions (fig. 12). 



Larvae of grass shrimp, Palaemonetes pugio, were exposed 

 continuously during development to several combinations of 

 temperature, salinity, and zinc concentration. The larvae were 

 most sensitive to zinc at low salinity and high temperature, and 

 zinc exposure significantly modified respiratory responses of the 

 larvae to stressful temperature/salinity regimes. 



Experiments on the effects of pollutants on the corticosteroid 

 stress response in marine fish and ascorbic acid metabolism in 

 marine fish and invertebrates show that chronic exposure to low 

 levels of phenanthrene or dichloronaphthalene produced unex- 

 pected fluctuations in whole body free ascorbic acid levels in 

 fish embryos, juvenile fish, and grass shrimp. These fluctuations 

 in free ascorbate levels may represent a mobilization of ascor- 

 bate from the ascorbate-2 sulfate pool. Methods are currently 

 being developed for the simultaneous analysis of ascorbate and 

 ascorbate-2 sulfate in tissues to test this hypothesis. 



CONTROL 



3 p p m 



2 3 4 5 



EXPOSURE TIME (days) 



6 



Figure 9. — Survival of amphipods (Elasmopus pectenicrus) in the water soluble fraction of No. 2 fuel oil. 



12 



