THE BIOLOGY OF CORAL REEFS
229
z m which is from 30 to 100 m wide and from 8 to 15 m deep and is
largely covered with immense beds of Acropora cervicornis although
large colonies of M. annularis and Porites spp. also occur. (9) The
annularis zone, which was the deepest surveyed, contains a wealth of
massive coral colonies of which M . annularis is the most conspicuous
with few Acropora. This reaches a depth of about 30 m.
In his account of reefs off British Honduras, Stoddart (19624 agrees
with Goreau in considering M . annularis as the principal reef builder
with A. palmta, there attaining heights of 15 ft, a~ specialized for
life in the shallower areas protected by these massive corals.
Examination of reefs off the southern coast of Jamaica also revealed
zonation with increasing depth but with extensive hurricane damage.
I n general, therefore, there is the same pattern in these West Indian
reefs aa there is at Low Isles and other Australian reef formations (see
Fairbridge, 1950) or at Bikini. There are elaborate windward reefs
forming, to quote Goreau (196lb), " an organized coherent structure
adapted for maximum attenuation of mechanical stresses set up by the
constant battering of the seas " and possessing a vigour probably due
to a combination of clear water and abundant planktonic food. The
former, by its effect (to be described later) on the zooxanthellm,
increases the rate of calcification, the latter provides for growth of the
tissues and feeding surface. The major difference between fully exposed
reefs in the Indo-Pacific (e.g. the Outer Barrier or NE of Bikini) and the
Atlantic is the absence in the latter of a massive algal ridge breaking the
surface at low water of spring tides. There is almost complete resemblance between the leeward reefs. All are less consolidated and grow in
more turbid waters containing less zooplankton. They do not develop
under such continuous mechanical restraint and for that reason are
easily devastated by occasional cyclonic seas.
Unlike the Indo-Pacific, little of the West Indian coral fauna is ever
exposed between tide marks. In his account of the ecology of the shores
of Florida, Stephenson and Stephenson (1950) notes the presence
of only eight, all notoriously hardy, species in this zone.
VII. EROSION
The growth processes of reef-building organisms, of which hermatypic corals are the most important, must be great enough to offset,
probably normally more than offset, the effects of erosion. Destruction
is the result of biological and non-biological factors, the relative importance of which is often diflicult to determine. Newell and Imbrie
(1955) note the conflict of views concerning the relative significance of
229
z m which is from 30 to 100 m wide and from 8 to 15 m deep and is
largely covered with immense beds of Acropora cervicornis although
large colonies of M. annularis and Porites spp. also occur. (9) The
annularis zone, which was the deepest surveyed, contains a wealth of
massive coral colonies of which M . annularis is the most conspicuous
with few Acropora. This reaches a depth of about 30 m.
In his account of reefs off British Honduras, Stoddart (19624 agrees
with Goreau in considering M . annularis as the principal reef builder
with A. palmta, there attaining heights of 15 ft, a~ specialized for
life in the shallower areas protected by these massive corals.
Examination of reefs off the southern coast of Jamaica also revealed
zonation with increasing depth but with extensive hurricane damage.
I n general, therefore, there is the same pattern in these West Indian
reefs aa there is at Low Isles and other Australian reef formations (see
Fairbridge, 1950) or at Bikini. There are elaborate windward reefs
forming, to quote Goreau (196lb), " an organized coherent structure
adapted for maximum attenuation of mechanical stresses set up by the
constant battering of the seas " and possessing a vigour probably due
to a combination of clear water and abundant planktonic food. The
former, by its effect (to be described later) on the zooxanthellm,
increases the rate of calcification, the latter provides for growth of the
tissues and feeding surface. The major difference between fully exposed
reefs in the Indo-Pacific (e.g. the Outer Barrier or NE of Bikini) and the
Atlantic is the absence in the latter of a massive algal ridge breaking the
surface at low water of spring tides. There is almost complete resemblance between the leeward reefs. All are less consolidated and grow in
more turbid waters containing less zooplankton. They do not develop
under such continuous mechanical restraint and for that reason are
easily devastated by occasional cyclonic seas.
Unlike the Indo-Pacific, little of the West Indian coral fauna is ever
exposed between tide marks. In his account of the ecology of the shores
of Florida, Stephenson and Stephenson (1950) notes the presence
of only eight, all notoriously hardy, species in this zone.
VII. EROSION
The growth processes of reef-building organisms, of which hermatypic corals are the most important, must be great enough to offset,
probably normally more than offset, the effects of erosion. Destruction
is the result of biological and non-biological factors, the relative importance of which is often diflicult to determine. Newell and Imbrie
(1955) note the conflict of views concerning the relative significance of