Gschwend%20thesis.pdf

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June and September, it may be more reasonable to expect algal physiology
changes to cause the observed pentadecane seasonal increases. Algal in-
cubations conducted precisely at these times of year are necessary to
confirm this hypothesis.
Surprisingly, heptadecane was not produced and released at high
rates in these incubation experiments. This lack of release is in strong
contrast to the case of pentadecane. Previous workers (Clark and Blumer,
1967; Youngblood et al., 1971; and Youngblood and Blumer, 1973) have re-
ported the importance of this hydrocarbon in red algae. They found be-
tween 100 andlOOO ~g/gm dry weight of ~ed algae. At most, only a few
ng/gm dry weight/day were found in the present experiments. A standing crop
calculation similar to that performed for pentadecane indicates that this
rate would support about 0.5 to 2 ng/liter seawater. Many of the CD
year-round values are only slightly above this concentration range. Peak
heptadecane concentrations at CD may be derived from algal species or
physiological stages of algae not included in these studies.
The two green algae studied revealed very high production rates for
some unsaturated l7-carbon compounds. The retention time and GCMS data, :1;
c
along with the work of Youngblood et al. (1971), suggest that the com-
pound from Enteromorpha is cis-3-heptadecene. Since this compound shows
such a high release rate, one would expect to observe it along with pentade-
cane in seawater. This compound was not seen in CD seawater and reaffirms
the suggestion made by Schwarzenbach et al. (l978) that brown benthic algae
were the major source of pentadecane. Codium also demonstrated production
and release of another unsaturated heptadecene.
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