Relationship between symbiont density and photosynthetic carbon acquisition in the temperate coral Cladocora caespitosa
- 459 Downloads
This study quantified variation in net photosynthetic carbon gain in response to natural fluctuations in symbiont density for the Mediterranean coral Cladocora caespitosa, and evaluated which density maximized photosynthetic carbon acquisition. To do this, carbon acquisition was modeled as an explicit function of symbiont density. The model was parameterized using measurements of rates of photosynthesis and respiration for small colonies with a broad range of zooxanthella concentrations. Results demonstrate that rates of net photosynthesis increase asymptotically with symbiont density, whereas rates of respiration increase linearly. In combination, these functional responses meant that colony energy acquisition decreased at both low and at very high zooxanthella densities. However, there was a wide range of symbiont densities for which net daily photosynthesis was approximately equivalent. Therefore, significant changes in symbiont density do not necessarily cause a change in autotrophic energy acquisition by the colony. Model estimates of the optimal range of cell densities corresponded well with independent observations of symbiont concentrations obtained from field and laboratory studies of healthy colonies. Overall, this study demonstrates that the seasonal fluctuations, in symbiont numbers observed in healthy colonies of the Mediterranean coral investigated, do not have a strong effect on photosynthetic energy acquisition.
KeywordsScleractinian coral Photosynthesis Respiration Energy balance Symbiosis Optimality model
This work was supported by funding from the government of the Principality of Monaco to the Centre Scientifique de Monaco. We thank R. Rodolfo-Metalpa for coral collection and C. Rottier for assistance with coral culture.
- Anthony KRN, Hoogenboom MO, Grottoli A, Middlebrook R, Maynard J (2009) Energetics approach to predicting mortality risk from environmental stress: a case study of coral bleaching. Funct Ecol 23:539–550Google Scholar
- Fitt WK, McFarland FK, Warner ME, Chilcoat GC (2000) Seasonal patterns of tissue biomass and densities of symbiotic dinoflagellates in reef coral and relation to coral bleaching. Limnol Oceanogr 45:677–685Google Scholar
- FitzGerald LM, Szmant AM (1988) Amino acid metabolism: adaptations to low nutrient conditions? Proc 6th Int Coral Reef Symp 3:5–9Google Scholar
- Jassby AD, Platt T (1976) Mathematical formulation of the relationship between photosynthesis and light for phytoplankton. Limnol Oceanogr 21:540–547Google Scholar
- Jeffery SW, Humphrey GF (1975) New spectrophotometric equations for determining chlorophylls a, b, c1 and c2 in higher plants, algae and natural phytoplankton. Biochem Physiol Pflanz 167:191–194Google Scholar
- Kooijman SALM (2000) Dynamic energy and mass budgets in biological systems, 2nd edn. Cambridge University Press, CambridgeGoogle Scholar
- LaJeunesse TC, Bhagooli R, Hidaka M, deVantier L, Done T, Schmidt GW, Fitt WK, Hoegh-Guldberg O (2004) Closely related Symbiodinium spp. differ in relative dominance in coral reef host communities across environmental, latitudinal and biogeographic gradients. Mar Ecol Prog Ser 248:147–161CrossRefGoogle Scholar
- Leletkin VA, Titlyanov EA, Dubinsky Z (1996) Photosynthesis and respiration of the zooxanthellae in hermatypic corals habitated on different depths of the Gulf of Eilat. Photosynthetica 32:481–490Google Scholar
- R Development Core Team (2008) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org
- Smith GJ, Muscatine L (1986) Carbon budgets and regulation of the population density of symbiotic algae. Endocytobiosis Cell Res 3:212–238Google Scholar
- Titlyanov EA, Titlyanova TV, Tsukahara J, van Woesik R, Yamazoto K (1999) Experimental increases of zooxanthellae density in the coral Stylophora pistillata elucidate adaptive mechanisms for zooxanthellae regulation. Symbiosis 26:347–362Google Scholar