Calcification does not stimulate photosynthesis in the zooxanthellate scleractinian coral Stylophora pistillata

Abstract

The interaction between photosynthesis and calcification remains poorly known in zooxanthellate scleractinian corals. We tested whether calcification is a significant source of CO2 for photosynthesis in Stylophora pistillata. Rates of net photosynthesis, respiration, and calcification were measured on colonies incubated in synthetic seawater (SSW) controlled with respect to the inorganic carbon system and containing standard (11.40 mmol kg−1) and low (2.85 mmol kg−1) calcium concentrations. Net photosynthesis and respiration are not significantly different in standard and low‐Ca2+ SSW despite a rate of calcification 2.0–2.4 times lower in Ca2+−depleted SSW. Additional experiments carried out on the noncalcifying zooxanthellate Anthozoa Anemonia viridis demonstrate that a low calcium concentration has no direct effect on rates of photosynthesis and respiration. It is suggested that calcification is not a significant source of photosynthetic CO2 and that photosynthesis stimulates calcification rather than the opposite.

Review: geological and experimental evidence for secular variation in seawater Mg/Ca (calcite-aragonite seas) and its effects on marine biological calcification

“…The Gattuso et al (2000) experiment also revealed that the reduced calcification observed for the zooxanthellate scleractinian coral Stylophora pistillata reared under low-[Ca 2+ ] conditions was not accompanied by reduced photosynthesis. Thus, in contrast to some species of bryopsidalean (Ries, 2005a(Ries, , 2006a(Ries, , 2009Stanley et al, 2010) and coccolithophorid algae (Stanley et al, 2005), calcification appears not to stimulate photosynthesis within zooxanthellate scleractinian corals.…”

“…Other experiments on specimens of Acropora sp., Stylophora pistillata, Acropora cervicornis and Acropora formosa show that calcification rates increase as Ca 2+ concentrations are elevated from approximately 20% to 80% of normal marine values (Chalker, 1976;Gattuso et al, 1998Gattuso et al, , 2000. At Ca 2+ concentration above 80%, calcification rates level out and, in some cases, decline.…”

Imbalanced coral growth between organic tissue and carbonate skeleton caused by nutrient enrichment

“…Calcification rates have been observed to be higher in light than in dark (e.g., Kawaguti and Sakumoto 1948), suggesting photosynthetic stimulation of calcification. The opposite interaction, i.e., stimulation of photosynthesis by calcification, has also been suggested in several studies (McConnaughey 1991;McConnaughey and Whelan 1997), though Gattuso et al (2000) argued that CO 2 released by calcification was not a significant source for algal photosynthesis. Suzuki et al (1995) simulated a model of coexisting effects of photosynthesis and calcification and showed that both reactions potentially enhance each other.…”

Heterotrophic feeding as a newly identified survival strategy of the dinoflagellate Symbiodinium

“…mixotrophy | zooxanthella | coral bleaching | food web | Heterosigma C orals in the ocean have drawn much attention from scientists, tourists, fishermen, and government officials (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Freeliving and symbiotic dinoflagellates in the genus Symbiodinium (also known as zooxanthellae) were once considered exclusively photosynthetic, except for the uptake of dissolved organic materials (17).…”