224
A. D. BONEY
1963). The results of the clearance experiments described above show
that there is a dynamic relationship between the population of algae,
limpets and barnacles in a wave-beaten shore. I n earlier pages reference
was made to the slow rate of recuperation by Ascophyllurn nocEosum
plants after too severe harvesting. Observations have shown that this
is in part due to the depredations of Littorina species, which browse
heavily on the Ascophyllurn sporelings (Knight and Parke, 1950). In
sublittoral habitats the browsing activity of species of %chinus can
severely depopulate the algal cover (Forster, 1969). The action of
browsing herbivores on giant kelps (Macrocystis) waa referred to in
earlier pages. This included kelp-eating fishes, the gammarids
Amphithoe humeralis and Idothea resemta, and sea urchins. Reference
has also been made to the digestive tracts of some marine invertebrates
possessing enzymes capable of splitting the polysacchmides of marine
algae, and in some instances containing bacteria which can bring about
this chemical breakdown. There are also many references to the animal
populations associated with the holdfasts of kelps (Macrocystis,
Nereocystis, Laminaria sp.), and that many animals browse on the
surface of algae in order to feed on the diatom or bacterial film (summarized in Scagel, 1969). In this last case the damage to the algae can
cause a weakening of the thalli. Saito and Nakamura (1961) have
described the severe depredation of the thalli of Undaria pinnatijida
by the sea hare Aplysia juliancc Quoy and Gaimard, and m d e estimates
of the quantities of plant tissue devoured by the mollusc. Both
Chondrw and Qigartina can suffer damage from browsing animals and
show a proliferation of new branches aa a result (Marshall et al., 1949).
The dynamic interrelationship between browsing activity and the algal
population on wave-beaten shores described earlier has its counterpart
in the sublittoral balance between Hacrocystis and its predators (p. 161) ;
the more serious effects of the browsing animals on Macrocystis plants
transplanted from another area are also relevant to proposals that
large-scale transplantations of brown algae might be attempted, e.g.
transplantation of Macrocystis to sublittoral habitats in Scotland.
XI. CONCLUSIONS
Anyone preparing a review of the seaweeds of economic importance
must be impressed by the wealth of data accumulated over the years.
In fact the statements which imply that there is little chance of development of a major industry seem belied by the masses of data which so
frequently appear. The scope of seaweed utilization, both direct and
for extractives, is at present extensive, and there is plenty of evidence
A. D. BONEY
1963). The results of the clearance experiments described above show
that there is a dynamic relationship between the population of algae,
limpets and barnacles in a wave-beaten shore. I n earlier pages reference
was made to the slow rate of recuperation by Ascophyllurn nocEosum
plants after too severe harvesting. Observations have shown that this
is in part due to the depredations of Littorina species, which browse
heavily on the Ascophyllurn sporelings (Knight and Parke, 1950). In
sublittoral habitats the browsing activity of species of %chinus can
severely depopulate the algal cover (Forster, 1969). The action of
browsing herbivores on giant kelps (Macrocystis) waa referred to in
earlier pages. This included kelp-eating fishes, the gammarids
Amphithoe humeralis and Idothea resemta, and sea urchins. Reference
has also been made to the digestive tracts of some marine invertebrates
possessing enzymes capable of splitting the polysacchmides of marine
algae, and in some instances containing bacteria which can bring about
this chemical breakdown. There are also many references to the animal
populations associated with the holdfasts of kelps (Macrocystis,
Nereocystis, Laminaria sp.), and that many animals browse on the
surface of algae in order to feed on the diatom or bacterial film (summarized in Scagel, 1969). In this last case the damage to the algae can
cause a weakening of the thalli. Saito and Nakamura (1961) have
described the severe depredation of the thalli of Undaria pinnatijida
by the sea hare Aplysia juliancc Quoy and Gaimard, and m d e estimates
of the quantities of plant tissue devoured by the mollusc. Both
Chondrw and Qigartina can suffer damage from browsing animals and
show a proliferation of new branches aa a result (Marshall et al., 1949).
The dynamic interrelationship between browsing activity and the algal
population on wave-beaten shores described earlier has its counterpart
in the sublittoral balance between Hacrocystis and its predators (p. 161) ;
the more serious effects of the browsing animals on Macrocystis plants
transplanted from another area are also relevant to proposals that
large-scale transplantations of brown algae might be attempted, e.g.
transplantation of Macrocystis to sublittoral habitats in Scotland.
XI. CONCLUSIONS
Anyone preparing a review of the seaweeds of economic importance
must be impressed by the wealth of data accumulated over the years.
In fact the statements which imply that there is little chance of development of a major industry seem belied by the masses of data which so
frequently appear. The scope of seaweed utilization, both direct and
for extractives, is at present extensive, and there is plenty of evidence