levels of mortalities during egg production in the natural environment are 

 high. It is difficult to assess the effect of additional mortalities caused 

 by oil on the cod and pollock in the area of the spill. More observations 

 will be required to properly evaluate the population impact. 



4.1.4 Effects of Oil on Developing Embryos 



This section was contributed by W. Kiihnhold, the visiting expert from 

 the University of Kiel, FRG, at NMFS, NEFC, Narragansett , Rhode Island. 

 Samples collected on the first cruise of the Belawave II DE 76-13 were used 

 in these studies. 



Laboratory experiments on the effects of No. 6 fuel oil on pelagic eggs 

 W. Kiihnhold and P. Lef court. These experiments deal with the direct effects 

 of an oil film on floating eggs and also with the effects of the water solu- 

 ble fraction of No. 6 oil on developing embryos. 



At Station 9, which was located at the periphery of the oil-contaminated 

 area, it appeared that oil was adhering in significantly greater quantities 

 to pollock eggs than to cod eggs in neuston samples. To determine whether 

 there were differences in surface membrance characteristics of the eggs that 

 could result in differential adherence to the oil, experiments involving the 

 exposure of pelagic eggs to an oil film were initiated jointly at the North- 

 east Fisheries Center's Narragansett Laboratory and the EPA Laboratory, 

 Narragansett, by E. Jackim and R. Pruell. In these experiments, cod eggs 

 were kept floating under an oil film, which was then stirred both gently and 

 vigorously to mix the eggs with the oil. In no case was there any sign of 

 oil adhering to the living eggs. The same results have been reported for cod 

 eggs by James (1925) and by Kiihnhold (1972) in tests with crude oil of a 

 similar visocisty. So far, only cod eggs have been available for this test. 

 The NMFS Narragansett Laboratory plans to expand this study to include pela- 

 gic eggs of several species, especially pollock, in order to determine 

 whether there are differences in surface responses of fish egg membranes to 

 oil among important fish species. 



The experiments to determine the effect of the water-soluble fraction 

 (WSF) of No. 6 oil conducted in cooperation with D. Everich of EPA have not 

 been completed, and only preliminary results are available. These experi- 

 ments are carried out as static tests to approximate conditions of an acute 

 spill situation where a body of water may be covered with an oil slick for a 

 short time only. The dissolved compounds are then subject to evaporation. 

 The extraction of No. 6 fuel oil was prepared according to Hyland (1973) to 

 provide concentrations of WSF comparable to earlier studies. Since no data 

 were available about actual concentrations of WSF of the Argo Mevohant oil 

 at the spill site, initial concentrations of 500, 100, and 10 parts per 

 billion (ppb) of total extractable hydrocarbons, WSF, were used. The loss of 

 hydrocarbons during the course of the tests appears to be low, less than 50% 

 in 10 days. Cod eggs were exposed at three different embryonic stages: 4 to 

 6 hours (2-cell stage), and 3- and 7-day old embryos. 



High mortality was evident in the youngest embryo group at the highest 

 concentration (500 ppb) after 24 hours. It was observed that the eggs held 



107 



