BIOLOGY OF SEAWEEDS OF EUONOldIU IMPORTANOE
226
that there will be further large-scale exploitation. We may therefore
enquire into the extent to which the available knowledge has made
any positive contribution to a more effective usage of the available
stocks of marine algae.
Whilst in many instances studies on the autecology of brown and
red algae have indicated the best times when frondage can be removed
without too serious an effect on subsequent plant growth, there are
still quite common examples in which the cycle of events is still not
known with any certainty, e.g. the problem of recuperative growth in
AscrvphyUum. For a number of species there is now a much clearer
picture of the link between annual phases of growth and reproduction
and the condition of the extractives. But there are still several representatives of potential value as sources of extractive for which more
detailed studies of their autecology would be necessary before any
large-scale usage is envisaged, e.g. Gelidium species at present used on
a small-scale, Eucheuma sp., Hypnea mzl.ct&mn&.
Studies on the periodicity of sporing and on the quantities of spores
liberated, and on the settlement, attachment and early growth stages
have been carried out under both field and laboratory conditions, and
have shown that for some species an extension of the areas under
cultivation is possible. For example, the microscopic gametophytes of
Laminaria can be cultured under laboratory conditions and the young
sporophytes reared and later transplanted in the sea. " Nursery "
growth of the young stages offers some scope for increming the standing
crops of some representatives. Culturing the Conchocel~8-phase of
Porphyra in oyster shells suspended in culture tanks on land m praotised in Japan (p. 182) appears to have markedly increased the produotivity. Sowing the spores on artificial surfaces under suitable conditions on land and then planting the germlings out in the sea appears
to be a more successful method than collecting the spores from fnriting
plants and using them directly. For a few species there is also some
evidence that a combined knowledge of fruiting periodicity and of times
of tides and directions of water currents enables some prediction to
be made of the mew where maximal spore settlements can be obtained.
Crop plants on land are studied for information on the value of
their products, and for knowledge of their growth and reproductive
phases, and the ways in which all these are influenced by environmental factors. The effects of parasites (fungal and animal) and of
nutrient deficiencies are also examined. Many of the topics of investigation carried out with the seaweeds of economic importance over recent
years have been of a similar nature to those outlined above. There is a
good deal of information now on the seasonal fluctuations in the extraL Y . B . 4
Y
226
that there will be further large-scale exploitation. We may therefore
enquire into the extent to which the available knowledge has made
any positive contribution to a more effective usage of the available
stocks of marine algae.
Whilst in many instances studies on the autecology of brown and
red algae have indicated the best times when frondage can be removed
without too serious an effect on subsequent plant growth, there are
still quite common examples in which the cycle of events is still not
known with any certainty, e.g. the problem of recuperative growth in
AscrvphyUum. For a number of species there is now a much clearer
picture of the link between annual phases of growth and reproduction
and the condition of the extractives. But there are still several representatives of potential value as sources of extractive for which more
detailed studies of their autecology would be necessary before any
large-scale usage is envisaged, e.g. Gelidium species at present used on
a small-scale, Eucheuma sp., Hypnea mzl.ct&mn&.
Studies on the periodicity of sporing and on the quantities of spores
liberated, and on the settlement, attachment and early growth stages
have been carried out under both field and laboratory conditions, and
have shown that for some species an extension of the areas under
cultivation is possible. For example, the microscopic gametophytes of
Laminaria can be cultured under laboratory conditions and the young
sporophytes reared and later transplanted in the sea. " Nursery "
growth of the young stages offers some scope for increming the standing
crops of some representatives. Culturing the Conchocel~8-phase of
Porphyra in oyster shells suspended in culture tanks on land m praotised in Japan (p. 182) appears to have markedly increased the produotivity. Sowing the spores on artificial surfaces under suitable conditions on land and then planting the germlings out in the sea appears
to be a more successful method than collecting the spores from fnriting
plants and using them directly. For a few species there is also some
evidence that a combined knowledge of fruiting periodicity and of times
of tides and directions of water currents enables some prediction to
be made of the mew where maximal spore settlements can be obtained.
Crop plants on land are studied for information on the value of
their products, and for knowledge of their growth and reproductive
phases, and the ways in which all these are influenced by environmental factors. The effects of parasites (fungal and animal) and of
nutrient deficiencies are also examined. Many of the topics of investigation carried out with the seaweeds of economic importance over recent
years have been of a similar nature to those outlined above. There is a
good deal of information now on the seasonal fluctuations in the extraL Y . B . 4
Y