206
A. D. BONEY
and laminarin contents show three annual peaks, in June, September
and December. The alginic acid content of the thalli was generally
higher than that of the Laminaria species examined (p. 202), and
Ascophyllum plants in open sea habitats contained more alginic acid
than those growing in sheltered sea lochs. By contrast, the mannitol
and laminarin contents of the sea loch plants were greater. Barry and
Flood (1958) reported that the alginic acid in 3-6 year old plants of
Ascophyllum growing in Dublin Bay was at a minimum in April but
rapidly increased to a maximum value in June. Larsen and Haug (1958a)
showed that habitat conditions, notably variations in salinity, had a
marked effect on the chemical composition of Ascophyllum nodosum.
Results for the other shore fucoids (Pelvetia canaliculata, Fucus
spiralis, F . vesiculosus, F . serratus), have shown some gradation in
the seasonal variations in chemical composition which can probably
be linked with the degree of immersion in their shore habitats. Minimum
dry weights, corresponding with minimum ash, mannitol and laminarin
were observed in January and February. Thence through spring and
into early summer the ash, mannitol and the dry weight increased.
During July and August, Pelvetia canaliculata and Fucus spiralis
showed a fall in dry weight, laminarin and mannitol, but with F . serratus
and F . vesiculosus this fall was delayed until autumn. I n fact, the
mannitol and laminarin reserves showed two annual peaks in all
representatives, e.g. early summer and late autumn. The plants which
are immersed for longer periods ( F . serratus and F . vesiculosus) have
higher mannitol contents than F . spiralis and Pelvetia canaliculata.
Alginic acid appears to reach a maximum value in January and February, but decreases during the summer months. The seasonal variations
seem to be far more marked in plants growing in the zones lower down
the shore, e.g. Fucus vesiculosus and F . serratus. It is possible that
there is a more regular pattern of metabolism and turnover of reserves
in plants found in the higher shore zones. The growth rates of the plants
found in the upper shore zones are slower than those lower down,
however, and recuperation is a slower process.
Moss (1948) studied the chemical composition of plants of Fucus
vesiculosus collected from different habitats, ranging from that sheltered
from wave action to one receiving the full force of the open sea. In
general, chemical composition could be related to the variation in thallus
form and structure associated with a habitat, and some gradation was
observed along the length of the thalli. Generally the younger (distal)
tissues contained the larger quantities. However, when plants are
harvested the bulk of the frondage is removed, so that total weights are
of greater significance, and these indicated that the alginic acid and
A. D. BONEY
and laminarin contents show three annual peaks, in June, September
and December. The alginic acid content of the thalli was generally
higher than that of the Laminaria species examined (p. 202), and
Ascophyllum plants in open sea habitats contained more alginic acid
than those growing in sheltered sea lochs. By contrast, the mannitol
and laminarin contents of the sea loch plants were greater. Barry and
Flood (1958) reported that the alginic acid in 3-6 year old plants of
Ascophyllum growing in Dublin Bay was at a minimum in April but
rapidly increased to a maximum value in June. Larsen and Haug (1958a)
showed that habitat conditions, notably variations in salinity, had a
marked effect on the chemical composition of Ascophyllum nodosum.
Results for the other shore fucoids (Pelvetia canaliculata, Fucus
spiralis, F . vesiculosus, F . serratus), have shown some gradation in
the seasonal variations in chemical composition which can probably
be linked with the degree of immersion in their shore habitats. Minimum
dry weights, corresponding with minimum ash, mannitol and laminarin
were observed in January and February. Thence through spring and
into early summer the ash, mannitol and the dry weight increased.
During July and August, Pelvetia canaliculata and Fucus spiralis
showed a fall in dry weight, laminarin and mannitol, but with F . serratus
and F . vesiculosus this fall was delayed until autumn. I n fact, the
mannitol and laminarin reserves showed two annual peaks in all
representatives, e.g. early summer and late autumn. The plants which
are immersed for longer periods ( F . serratus and F . vesiculosus) have
higher mannitol contents than F . spiralis and Pelvetia canaliculata.
Alginic acid appears to reach a maximum value in January and February, but decreases during the summer months. The seasonal variations
seem to be far more marked in plants growing in the zones lower down
the shore, e.g. Fucus vesiculosus and F . serratus. It is possible that
there is a more regular pattern of metabolism and turnover of reserves
in plants found in the higher shore zones. The growth rates of the plants
found in the upper shore zones are slower than those lower down,
however, and recuperation is a slower process.
Moss (1948) studied the chemical composition of plants of Fucus
vesiculosus collected from different habitats, ranging from that sheltered
from wave action to one receiving the full force of the open sea. In
general, chemical composition could be related to the variation in thallus
form and structure associated with a habitat, and some gradation was
observed along the length of the thalli. Generally the younger (distal)
tissues contained the larger quantities. However, when plants are
harvested the bulk of the frondage is removed, so that total weights are
of greater significance, and these indicated that the alginic acid and