RESULTS 



Funis zygotes were much more tolerant of salinity-temperature extremes 

 than were Laminaria gametophytes (Table 8-1). This is probably a reflection of 

 their habitats; Fucus, being intertidal and growing in a more variable 

 environment than the subtidal Laminaria, is adapted to a wider range of 

 environmental conditions. Optimal growth of Fucus was at 18 C and 30-42 

 ppt while that of Laminaria was at 1 2- 1 8° C and 24-36 ppt. There appeared 

 to be some seasonal variability in Laminaria\ optimal temperature for growth. 

 Fertile Laminaria collected during the colder winter months produced spores 

 that germinated and grew slightly better at 12°C than at 18^C; the converse 

 was true for Laminaria collected during tlie warmer spring months. In the 

 following experiments to determine the toxicity of different oils, the standard 

 conditions were 18°C and 30 ppt for Fucus and 12°C and 30 ppt for 

 Laminaria. 



Of the four types of oil tested, No. 2 fuel oil was the most toxic to Fucus 

 zygotes, and the jet fuels, JP-4 and JP-5, were least toxic (Table 8-2). There 

 appeared to be a slight stimulation at lower levels (200 ppb or less), except for 

 Willamar crude. This may be due to a surfactant effect on the part of the oil. 

 Above those levels, these oils became increasingly deleterious to growth. 



The toxicity of the four oils to Laminaria gametophytes was similar to 

 that of Fucus zygotes, although at lower levels, Laminaria response was not 

 comparable to Fucus (Table 8-3). Number two fuel oil was still the most 

 toxic, although not as relatively toxic as it was to Fucus. The jet fuels, JP-4 

 and JP-5, were somewhat more toxic to Lamz>iar/a than they were to Fucus. 

 The lower growth rate of Laminaria gametophytes compared to Fucus 

 zygotes is probably a reflection of their different growth habits. Laminaria 

 gametophytes are much smaller, and grow in a more radial fashion than do 

 Fucus zygotes. 



PreUminary experiments on apphcation of oil during gamete release in 

 Fucus, and spore release in Laminaria, indicate that these brown algae may be 

 extremely sensitive to oils (Table 8-4). 



Concentrations greater than 20 ppb of No. 2 fuel oil were completely toxic 

 to Laminaria spores. Even at 2 ppb, significant inhibition of the resulting 

 gametophytes occurred. Fucus was even more sensitive. At 2 ppb, fertilization 

 of eggs was blocked, apparently due to a toxicity effect on the sperm. 



DISCUSSION 



It is somewhat difficult to compare the results of these bioassays with 

 brown algae, with those developed with other organisms by different 



105 



