RESULTS 
Fucus 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 
o/oo while that of Laminaria was at 12 - 18°C and 24-36 o/oo. There appeared 
to be some seasonal variability in Laminaria's 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 the warmer spring months. In the 
following experiments to determine the toxicity of different oils, the standard 
conditions were 18°C and 30 o/oo for Fucus and 12°C and 30 o/oo 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 is 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 Laminaria 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. 
Preliminary experiments on application 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 
