Gschwend%20thesis.pdf

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Production of halogenated methanes was found in these incuba-
t ions. All of these compounds have been previously reported from a
red alga, Asparagopsis taxiformis (Moore, 1976). Halogenation in
the Rhodophyta has been extensively documented (see Fenical, 1975
for review), but little work has been done on other algal classes.
Members of every algal class showed production of bromoform
(tribromomethane). The low levels of apparent production by the
vascular plant, Zostera, were quite startling, however. Epiphytic
algae or attached microorganisms may have been responsible. Also
Zostera may have accumulated this compound from the surrounding
seawater only to release it upon stripping. These sorts of "pro-
duction" mechanisms may also be operating for some of the algae ex-
amined and ex?lain the prevalence of this production.
An examination of the Fucus data suggests that maximum release
of bromoform occurs in the middle of the summer, at a time when the
algae may have been dormant (Conover, 1958). If a tribromo-2-keto-
compound were present in the essential oil of this brown alga and
were released during this period into the seawater, decomposition to
produce bromoform would occur (Burreson et al., 1976, quoted in Moore,
1977) .
Lesser amounts of chlorodibromomethane were also frequently
produced with bromoform; however strong production of this com-
pound was confined to the brown algae samples.
Release rates of 20-40 ng haloform*/gm dry weight/day suggest
that standing stocks of 1-2 ng*/liter s~awater would result in coastal
seawater. Such levels of bromoform were observed in the year-round
*Note that these weight values underestimate the true halo
due to insensitivity of an FIb
form levels
relative to the l-cl-nC8 internal standard.