BIOLOGY O F SEAWEEDS O F ECONOMIC IMFORTANCE
135
Studies by Provasoli (1958) on the growth of Ulva plants in bacteriafree culture have shown that growth of the normal foliaceous thallus
is not readily obtainable from the Glamentous germlings. “ Islands ”
of dark green cells were observed in the bleached germlings, and these
cells produced fresh germlings on transference to new culture medium.
Under culture conditions plant hormones were found to be necessary
for normal morphogenesis. Such compounds are available in appreciable quantities in coastal waters with a high bacterial contamination,
and may influence the growth of all types of seaweeds in areas under
cultivation.
B. Phaeophyceae
1. Productivity of benthic intertidal marine algae
Some quantitative data on this aspect of the biology of the larger
marine algae has become available in recent years, and will be described
in the relevant sections under discussion. The importance of continuous
remineralization of decomposition products of the littoral algae has
been stressed in some recent papers (Hoffmann and Reinhardt, 1962 ;
Hoffmann, 1963). Some of the commoner marine algae have been found
to remineralize 30% of their organic phosphorus content within 12
hours. Kuznetzov (1956) estimated that for the shores of the Barents
and White Seas the annual production of plant organic matter per metre
of shore was equal to 180 kg. For this he estimated that 877.6 gm of
nitrogen would be required, and this quantity was contained in
16 953 m3 of sea water at the time of maximum nitrogen content. The
quantity of sea water ‘‘ available ” for 1 metre of shore was estimated
at 60 m3, however. I n laboratory experiments with Fucus vesiculosus
0.62 mg nitrate-N was found to be necessary per 9 gm of plant per day,
and 0-63 mg of this would enable an algal growth rate of 8 mg/g/day.
I n fact under field conditions the growth rates were found to be 7-2
mg/g/day. Blinks (1955) estimated that the productivity per unit area
of the littoral zone equalled 100 times that in the open sea. Conover
(1968) has reported on a study of the standing crops of benthic marine
algae.
2. Fucus
Fucus vesiculosus and F. serratus are the two species utilized in
greatest quantities. The most detailed study of the seasonal ecology of
the two species was that carried out by Knight and Parke (1960), and
it is intended to summarize here only the data relevant to the problem
of economic utilization.
I n the British Isles Fucus vesiculosus is found zoned in the mid-
135
Studies by Provasoli (1958) on the growth of Ulva plants in bacteriafree culture have shown that growth of the normal foliaceous thallus
is not readily obtainable from the Glamentous germlings. “ Islands ”
of dark green cells were observed in the bleached germlings, and these
cells produced fresh germlings on transference to new culture medium.
Under culture conditions plant hormones were found to be necessary
for normal morphogenesis. Such compounds are available in appreciable quantities in coastal waters with a high bacterial contamination,
and may influence the growth of all types of seaweeds in areas under
cultivation.
B. Phaeophyceae
1. Productivity of benthic intertidal marine algae
Some quantitative data on this aspect of the biology of the larger
marine algae has become available in recent years, and will be described
in the relevant sections under discussion. The importance of continuous
remineralization of decomposition products of the littoral algae has
been stressed in some recent papers (Hoffmann and Reinhardt, 1962 ;
Hoffmann, 1963). Some of the commoner marine algae have been found
to remineralize 30% of their organic phosphorus content within 12
hours. Kuznetzov (1956) estimated that for the shores of the Barents
and White Seas the annual production of plant organic matter per metre
of shore was equal to 180 kg. For this he estimated that 877.6 gm of
nitrogen would be required, and this quantity was contained in
16 953 m3 of sea water at the time of maximum nitrogen content. The
quantity of sea water ‘‘ available ” for 1 metre of shore was estimated
at 60 m3, however. I n laboratory experiments with Fucus vesiculosus
0.62 mg nitrate-N was found to be necessary per 9 gm of plant per day,
and 0-63 mg of this would enable an algal growth rate of 8 mg/g/day.
I n fact under field conditions the growth rates were found to be 7-2
mg/g/day. Blinks (1955) estimated that the productivity per unit area
of the littoral zone equalled 100 times that in the open sea. Conover
(1968) has reported on a study of the standing crops of benthic marine
algae.
2. Fucus
Fucus vesiculosus and F. serratus are the two species utilized in
greatest quantities. The most detailed study of the seasonal ecology of
the two species was that carried out by Knight and Parke (1960), and
it is intended to summarize here only the data relevant to the problem
of economic utilization.
I n the British Isles Fucus vesiculosus is found zoned in the mid-