Reef Science: Development Highlights
L. Shimek, Ph. D.
This month, I will discuss an interesting
article on morphological change in aquarium corals...
Todd, P.A., R.C. Sidle, and N.J.I. Lewin-Koh,
2004. An Aquarium Experiment For Identifying The Physical
Factors Inducing Morphological Change In Two Massive Scleractinian
Corals. Journal of Experimental Marine Biology and Ecology.
299: 97- 113.
Previous research has demonstrated that
the massive corals Favia speciosa (Dana, 1846) and
Diploastrea heliopora (Lamark, 1816) are phenotypically
plastic; i.e., the phenotype of these species can be altered
by environmental conditions within their life span. Many researchers
have suggested that light, water movement and/or sediment
can affect coral morphology, but no work to date has attempted
to separate these variables in a controlled aquarium experiment.
To ascertain whether any of these three factors could induce
morphological change in F. speciosa and D. heliopora,
fragments (clone-mates) of both species were maintained in
five aquariums, representing: high water energy, high sedimentation,
and three different light regimes. After four months, the
architecture of 12 randomly chosen corallites from each fragment
was measured. Reaction norms suggest a relationship between
corallite morphology and light, but no consistent pattern
could be detected for fragments kept in the sediment regime
tank or the high water energy tank. Corallites expand, extend
and deepen in high light conditions, and possible functional
explanations for this response are presented. However, more
research is necessary to confirm that light is the primary
controlling factor inducing small-scale morphological change
in F. speciosa and D. heliopora.
Many aquarists would benefit from taking
a look at this article. There are many glib statements in
the aquarium literature and on various forums about testing
various factors and their effects on corals. This study actually
does some of those tests, in aquaria, no less. More than just
showing the results of this particular study of the effects
of changes in light, water movement and sediment between two
corals, this study illustrates some of the complicated equipment
and methodology needed to examine some of these simple questions
in an aquarium situation.