Symbiont diversity is not involved in depth acclimation in the Mediterranean sea whip Eunicella singularis

Forcioli, D., Merle, P.L., Caligara, C., Ciosi, M. , Muti, C., Francour, P., Cerrano, C. and Allemand, D. (2011) Symbiont diversity is not involved in depth acclimation in the Mediterranean sea whip Eunicella singularis. Marine Ecology Progress Series, 439, pp. 57-71. (doi: 10.3354/meps09314)




In symbiotic cnidarians, acclimation to depth and lower irradiance can involve physiological changes in the photosynthetic dinoflagellate endosymbiont, such as increased chlorophyll content, or qualitative modifications in the symbiont population in favour of better adapted strains. It has been argued that a lack of capacity to acquire new symbionts could limit the bathymetric distribution of the host species, or compromise its long-term survival in a changing environment. But is that always true? To address this question, we investigated the symbiont genetic diversity in Eunicella singularis, a Mediterranean sea whip species with a wide bathymetric distribution (10 to 50 m depth), which has recently suffered from mass mortalities after periods of abnormally high sea temperatures. We measured symbiont population densities and chlorophyll content in natural populations, and followed the response of the holobionts after reciprocal transplantations to deep and shallow depths. A total of 161 colonies were sampled at 2 depths (10 and 30 m) at 5 sites in the northwestern Mediterranean. All colonies harboured a single ribosomal Symbiodinium clade (A'), but a relatively high within-clade genetic diversity was found among and within colonies. This diversity was not structured by depth, even though the deeper colonies contained significantly lower population densities of symbionts and less chlorophyll. We did, however, reveal host-symbiont specificity among E. singularis and other Mediterranean cnidarian species. Transplantation experiments revealed a limit of plasticity for symbiont population density and chlorophyll content, which in turn questions the importance of the trophic role of Symbiodinium in E. singularis.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Ciosi, Dr Marc
Authors: Forcioli, D., Merle, P.L., Caligara, C., Ciosi, M., Muti, C., Francour, P., Cerrano, C., and Allemand, D.
Subjects:Q Science > QH Natural history
Q Science > QH Natural history > QH301 Biology
Q Science > QH Natural history > QH426 Genetics
Q Science > QL Zoology
College/School:College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Marine Ecology Progress Series
Publisher:Inter Research
ISSN (Online):1616-1599
Published Online:20 October 2011
Copyright Holders:Copyright © 2011 Inter Research
First Published:First published in Marine Ecology Progress Series 439:57-71
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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