THE BIOLOGY OF CORdL REEFS
231
East Indies. Certainly in Pacific reefs, bivalve borers are no less
important. Recent work on probably the most important genus,
Lith@.uga, has clearly demonstrated the initial chemical nature of the
boring process and the nature of the modifications which have fitted
members of the Mytilidae for boring (Yonge, 1955 ; Hodgkin, 1962).
Crossland (1952) associated the more vigorous coral growth characteristic of seaward reefs with “ decreased activity of destructive
organisms ”. This is probably correct. The greatest surface of living
coral occurs there and this we have seen to be largely immune from
attack. Moreover, dead patches due to exposure or collections of
sediment are not found on these exposed colonies. The results of an
experiment involving local destruction of such seaward coral could be
very informative.
Although consideration of the mechanical effects of the sea on the
form of reefs lies outside the scope of this review, some of the effects of
cyclones may be briefly mentioned. After its careful survey in 1928-29,
Low Isles has suffered two cyclones, in 1934 and 1950. The effects of the
first were almost immediately studied by Moorhouse (1936) who
noted great destruction to branching corals such as Acropora and
relatively greater survival by colonies of the more rounded Favia,
Porites and the meandrines. He also observed peculiar effects in
Porites, due apparently to stimulation of skeletal growth after lowering
of the water level in the moats where these colonies live, which caused
extensive damage. His paper contains a map showing the principal
changes caused by the cyclone. A further, more detailed, survey was
made in 1945 by Fairbridge and Teichert (1947, 1948) and Fairbridge
(1950). They were particularly concerned with the formation of the
shingle ramparts which move across the reef flat from the seaward side
and of which four, the youngest probably originating after 1928,
perhaps even after 1934, were then recognizable. They regarded them
as in a state of ‘‘ progressive evolution ”. Damage by the cyclone had
been largely repaired. A further map was produced.
The effects of the second and less severe cyclone in 1950 were
studied 4 years later by Stephenson and Wells (1956) and Stephenson
et al. (1958). Here again branching coral had suffered heavily but maasive colonies had largely maintained themselves. The unstable fragments from the broken corals were still hampering recolonization on the
seaward side. Further changes in the shingle ramparts were noted.
These papers represent major additions to knowledge about this now
well-known reef, changes in which have been so carefully studied sinoe
its original survey in 1928-29.
Turning to Atlantic reefs, Stoddart (1962a, b) has followed up an
231
East Indies. Certainly in Pacific reefs, bivalve borers are no less
important. Recent work on probably the most important genus,
Lith@.uga, has clearly demonstrated the initial chemical nature of the
boring process and the nature of the modifications which have fitted
members of the Mytilidae for boring (Yonge, 1955 ; Hodgkin, 1962).
Crossland (1952) associated the more vigorous coral growth characteristic of seaward reefs with “ decreased activity of destructive
organisms ”. This is probably correct. The greatest surface of living
coral occurs there and this we have seen to be largely immune from
attack. Moreover, dead patches due to exposure or collections of
sediment are not found on these exposed colonies. The results of an
experiment involving local destruction of such seaward coral could be
very informative.
Although consideration of the mechanical effects of the sea on the
form of reefs lies outside the scope of this review, some of the effects of
cyclones may be briefly mentioned. After its careful survey in 1928-29,
Low Isles has suffered two cyclones, in 1934 and 1950. The effects of the
first were almost immediately studied by Moorhouse (1936) who
noted great destruction to branching corals such as Acropora and
relatively greater survival by colonies of the more rounded Favia,
Porites and the meandrines. He also observed peculiar effects in
Porites, due apparently to stimulation of skeletal growth after lowering
of the water level in the moats where these colonies live, which caused
extensive damage. His paper contains a map showing the principal
changes caused by the cyclone. A further, more detailed, survey was
made in 1945 by Fairbridge and Teichert (1947, 1948) and Fairbridge
(1950). They were particularly concerned with the formation of the
shingle ramparts which move across the reef flat from the seaward side
and of which four, the youngest probably originating after 1928,
perhaps even after 1934, were then recognizable. They regarded them
as in a state of ‘‘ progressive evolution ”. Damage by the cyclone had
been largely repaired. A further map was produced.
The effects of the second and less severe cyclone in 1950 were
studied 4 years later by Stephenson and Wells (1956) and Stephenson
et al. (1958). Here again branching coral had suffered heavily but maasive colonies had largely maintained themselves. The unstable fragments from the broken corals were still hampering recolonization on the
seaward side. Further changes in the shingle ramparts were noted.
These papers represent major additions to knowledge about this now
well-known reef, changes in which have been so carefully studied sinoe
its original survey in 1928-29.
Turning to Atlantic reefs, Stoddart (1962a, b) has followed up an