Morphological Changes in Polyp Structure of Massive Coral Species in Clear and Turbid Waters

We explored variations in polyp morphology of four ecologically important massive coral species, Porites lutea (Milne-Edwards and Haime, 1860), Diploastrea heliopora (Lamarck, 1816), Favia speciosa (Dana, 1846), and Favia matthaii (Vaughan, 1918), across a depth gradient and among sites of differing turbidity within the Wakatobi Marine National Park, Indonesia. Increased polyp area with decreased light availability was found in all target species except F. speciosa, whereas polyp density only varied across sites or depth in D. heliopora, P. lutea, and F. speciosa. Variability in polyp morphology may reflect both an optimization of light capture and an increase in heterotrophic efficiency of the host to compensate for decreased photosynthesis with depth. The morphological variability demonstrated in these key species, which acts to optimize environmental suitability, may be a crucial attribute that has contributed to the success and abundance of these species within the Wakatobi Marine National Park.