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A. D. BONEY
fronds are also seen in plants which are not subjected to regular cutting,
the weakened fronds after fruiting being more readily detached in the
winter months. Crop recovery is dependent on the holdfasts remaining
undamaged after cutting.*
July, August and early September have been suggested as the best
times for picking the fronds, since these are the months when the gel
strength of the extracted agar is high after the growth of the fronds
from the preceding spring. Harvesting at about this time would also
enable new frondage to become fertile later in the year. Quite frequent
annual cropping over the years seems to be possible. Attempts at
increasing the area of the lower shore where Gigartina grows have been
made by removal of the neighbouring algae, but have proved
unsuccessful because of colonization by more rapidly growing algae.
12. Chondrus
The frond and holdfast structure of Chondrus are similar to those
of Gigartina. Regeneration of new frondage from the cut surfaces of
the erect branches and from the holdfast region is frequently observed.
During the annual life of the plant considerable amounts of new branch
formation were observed during spring and summer for plants growing
in the British Isles (Marshall et al., 1949). In the field, new growth can
generally be distinguished by its different colour and the lack of
epiphytes. Plants growing in intertidal pools usually bear an annual
frondage, whilst in sublittoral habitats plants up to 3 years old may be
found. The intertidal plants are those mainly harvested on European
shores, whereas in North America the sublittoral plants are the principal
sources.
Plants bearing tetrasporangia, as well as those bearing sex organs,
are known to occur in the annual life of Chondrus. Observations on
fruiting periodicity for plants in the British Isles have been reported by
Marshall et al. (1949) and by Newton et al. (1957). Tetrasporangia are
mainly produced through winter and spring, and cystocarps are found
during the summer months. Discharge of tetraspores and carpospores
is followed by degeneration of the spent fruiting thalli, so that the
fruiting time is important for purposes of harvesting. In sublittoral
habitats it appears that the cystocarpic plants occur in quantity
during the winter months.
Experimental studies on the methods of harvesting and their
effects on the standing crop of Chondrus have been reported (Marshall
et al., 1949 ; MacFarlane, 1952a). Careless harvesting has been found to
have a more serious effect on Chondrus than on aigartina, since the
holdfast region of the plant is more easily detached in the former alga.
* Regulations governing Chondrus harvesting are now in existence in Nova Scotja.
A. D. BONEY
fronds are also seen in plants which are not subjected to regular cutting,
the weakened fronds after fruiting being more readily detached in the
winter months. Crop recovery is dependent on the holdfasts remaining
undamaged after cutting.*
July, August and early September have been suggested as the best
times for picking the fronds, since these are the months when the gel
strength of the extracted agar is high after the growth of the fronds
from the preceding spring. Harvesting at about this time would also
enable new frondage to become fertile later in the year. Quite frequent
annual cropping over the years seems to be possible. Attempts at
increasing the area of the lower shore where Gigartina grows have been
made by removal of the neighbouring algae, but have proved
unsuccessful because of colonization by more rapidly growing algae.
12. Chondrus
The frond and holdfast structure of Chondrus are similar to those
of Gigartina. Regeneration of new frondage from the cut surfaces of
the erect branches and from the holdfast region is frequently observed.
During the annual life of the plant considerable amounts of new branch
formation were observed during spring and summer for plants growing
in the British Isles (Marshall et al., 1949). In the field, new growth can
generally be distinguished by its different colour and the lack of
epiphytes. Plants growing in intertidal pools usually bear an annual
frondage, whilst in sublittoral habitats plants up to 3 years old may be
found. The intertidal plants are those mainly harvested on European
shores, whereas in North America the sublittoral plants are the principal
sources.
Plants bearing tetrasporangia, as well as those bearing sex organs,
are known to occur in the annual life of Chondrus. Observations on
fruiting periodicity for plants in the British Isles have been reported by
Marshall et al. (1949) and by Newton et al. (1957). Tetrasporangia are
mainly produced through winter and spring, and cystocarps are found
during the summer months. Discharge of tetraspores and carpospores
is followed by degeneration of the spent fruiting thalli, so that the
fruiting time is important for purposes of harvesting. In sublittoral
habitats it appears that the cystocarpic plants occur in quantity
during the winter months.
Experimental studies on the methods of harvesting and their
effects on the standing crop of Chondrus have been reported (Marshall
et al., 1949 ; MacFarlane, 1952a). Careless harvesting has been found to
have a more serious effect on Chondrus than on aigartina, since the
holdfast region of the plant is more easily detached in the former alga.
* Regulations governing Chondrus harvesting are now in existence in Nova Scotja.