scientific article | Bull Mar Sci
Studies on the distribution and photosynthetic chloroplast pigments of symbiotic zooxanthellae in the reef-building coral Montastrea annularis Ellis and Solander strongly suggest that photoadaptation to decreasing light intensity occurs within a population inhabiting the fore-reef of a West Indian (Jamaican) coral reef. It is suggested that the photoadaptation allows for the extension of the depth range of the species. The responses of M. annularis and its zooxanthellae to transplantation suggest that colonies have a certain capacity for modification when placed at different depths. The magnitude of these potential changes is small and colonies do not fare well in the transplant habitats. Such sub-optimal conditions are reflected in a decrease in algal density/cm2 living coral tissue, a decrease in zooxanthellar intracellular photosynthetic pigment concentration, and significant decreases in coral skeletal extension rates. Responses such as these are reasonably clear data in support of ecotypic variation and suggest that there are sun and shade populations of zooxanthellae in M. annularis.
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