Light-dependent calcification in Red Sea giant clam Tridacna maxima

Tropical giant clams of the subfamily Tridacninae, including the species Tridacna maxima, are unique among bivalves as they live in a symbiotic relationship with unicellular algae and generally function as net photoautotrophs. Light is therefore crucial for these species to thrive. Here we examine the light dependency of calcification rates of T. maxima in the central Red Sea as well as the patterns of its abundance with depth in the field. Red Sea T. maxima show the highest densities at a depth of 3 m with 0:82 ± 0:21 and 0:11±0:03 individuals m-2 (mean ± SE) at sheltered and exposed sites, respectively. Experimental assessment of net calcification (μmol CaCO3 cm-2 h-1) and gross primary production (μmol O2 cm-2 h-1) under seven light levels (1061, 959, 561, 530, 358, 244, and 197 μmol quanta m-2 s-1) showed net calcification rates to be significantly enhanced under light intensities corresponding to a water depth of 4 m (0:65 ± 0:03 μmol CaCO3 cm-2 h-1; mean ± SE), while gross primary production was 2:06±0:24 μmol O2 cm-2 h-1 (mean ± SE). We found a quadratic relationship between net calcification and tissue dry mass (DM in gram), with clams of an intermediate size (about 15 g DM) showing the highest calcification. Our results show that the Red Sea giant clam T. maxima stands out among bivalves as a remarkable calcifier, displaying calcification rates comparable to other tropical photosymbiotic reef organisms such as corals.

Citation

Rossbach, S., Saderne, V., Anton, A., & Duarte, C. M. (2019). Light-dependent calcification in Red Sea giant clam Tridacna maxima Biogeosciences, 16(13), 2635–2650. doi:10.5194/bg-16-2635-2019

Acknowledgements

Acknowledgements: We thank Janna Leigh Randle and Felix Ivo Rossbach for assistance with field sampling and the KAUST Coastal and Marine Resources Core Lab for logistical support.
Financial support: This research was funded by King Abdullah University of Science and Technology (KAUST), through baseline funding to Carlos M. Duarte, and a fellowship of the Visiting Student Research Program to Susann Rossbach.

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Is Supplemented By:

[Dataset]
Rossbach, S., Saderne, V., Anton, A., & Duarte, C. M. (2019). Abundance, primary production rates and net calcification rates of Tridacna maxima giant clams at two reefs in the Central Red Sea, supplement to: Rossbach, Susann; Saderne, Vincent; Anton, Andrea; Duarte, Carlos Manuel (2019): Light-dependent calcification in Red Sea giant clam Tridacna maxima. Biogeosciences, 16(13), 2635-2650. PANGAEA - Data Publisher for Earth & Environmental Science. https://doi.org/10.1594/PANGAEA.903560. DOI: 10.1594/PANGAEA.903560 Handle: 10754/662378
[Dataset]
Rossbach, S., Saderne, V., Anton, A., & Duarte, C. M. (2019). Abundance, primary production rates and net calcification rates of Tridacna maxima giant clams at two reefs in the Central Red Sea, supplement to: Rossbach, Susann; Saderne, Vincent; Anton, Andrea; Duarte, Carlos Manuel (2019): Light-dependent calcification in Red Sea giant clam Tridacna maxima. Biogeosciences, 16(13), 2635-2650. PANGAEA - Data Publisher for Earth & Environmental Science. https://doi.org/10.1594/PANGAEA.903560. DOI: 10.1594/pangaea.903560 Handle: 10754/662378

Permanent link to this record

http://hdl.handle.net/10754/656421

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Biological and Environmental Science and Engineering (BESE) Division
Marine Science Program
Red Sea Research Center (RSRC)

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