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Title: The specificity of temperate anthozoan-dinoflagellate symbioses
Author: Davy, Simon K.
ISNI:       0000 0001 3418 1063
Awarding Body: University of Wales, Bangor
Current Institution: Bangor University
Date of Award: 1994
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The aim of this study was to investigate the specificity of temperate dinoflagellate - anthozoan symbioses and the influence of any specificity on the percentage contribution of photosynthetically fixed carbon to the host's daily respiratory carbon budget (CZAR). The British symbiotic Anthozoa Cereus pedunculatus (Pennant) I Anthopleura ballii (Cocks), Anemonia viridis (Forskal) and Isozoanthus sulcatus (Gos3e) and the sub-tropical anthozoan Aiptasia pallida (Verrill) and their algal symbionts were investigated. The characteristics of freshly isolated and cultured symbionts were studied to determine whether the algal cells residing in each host species appeared different and how symbiont characteristics may be determined by the host environment. Horphology, division behaviour and photosynthetic pigment composition were examined using SEMO TEMO LMO TLC and HPLC respectively. The symbionts of each host species were identified as dinoflagellates of the genus Symbiodinium, even though there was an absence of a motile phase in the cell cycle of the British hosts. Differences between symbionts of different host species and conspecific hosts were evident with respect to thylakoid arrangement, cell size and cell division rate, and possibly pigment concentrations. Host determined phenotypic plasticity was observed with respect to the absence of a "pellicle". Host-symbiont recognition and specificity were investigated - by reinfecting aposymbiotic C. _pedunculatus with symbionts from different host species and measuring the density and biomass of symbionts at different time intervals. The presence of different strains or species of Symbiodinium was evident, with recognition of these different symbionts being predominantly post-endocytotic. 'Homologous' symbionts were the most 'successful' at repopulating C. pedunculatus. After 9 months, the population densities and biomasses, and division rates of the different 'strains' Of 3ymbionts were the same, suggesting a greater symbiotic integration with 'heterologous, 'strains' with time. The reflection of specificity by the photosynthetic fixation of carbon in vivo was measured using an 02 electrode. 1110mologous, symbiontW photosynthesized at a greater rate than 'heterologous' symbionts in vivo, despite the higher photosynthetic rates of some of these 'heterologous' symbionts in their original hosts. Photosynthate translocation by symbionts in response to different host environments was investigated using in vivo and in vitro 14C labelling and the 'growth rate method'. The percentage translocation was host-symbiont specific and appeared to be controlled by different mechanisms in different host species and conspecific hosts from different locations. The CZAR in 'natural' and reestablished symbioses was calculated. Values ranged from 25.7 to 112.2 % in the 'natural' symbi T9 es and 58.1 to 76.7 % in the reestablished symbioses when measured using C. When measured using the 'growth rate method' values were 73.2 to 188.4 % and 88.3 to 146.5 % respectively. The CZAR in the reestablished symbioses and consequently their ability to survive autotrophically reflected the specific host-symbiont relationship. Symbiosis specificity and the reduced availability of carbon to host growth and reproduction in 'heterologous' symbioses may limit 'novel' symbioses in the field.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Oceanography