The primary production of coral reefs is largely attributed to benthic
primary producers rather than planktonic ones because of the much
larger benthic biomass (Atkinson, 2011). Scleractinian corals are one
of the major benthic primary producers in coral reefs because they
have endosymbiotic algae (zooxanthellae) in the host animal tissue.
The algal cell density in corals is approximately on the order of millions
per 1 cm2 of the coral surface area and is affected by environmental
changes such as seawater temperature (Fagoonee et al., 1999) and
light intensity (Masuda et al., 1993). The areal photosynthetic and calci-
fication rates of corals are often influenced by the symbiotic algal density
(Gattuso et al., 1999; Marubini and Davies, 1996; Sawall et al., 2011).
Thus, the density of zooxanthellae in corals is an important parameter to
evaluate coral physiology and coral reef biogeochemistry