Symbiodinium diversity in the sea anemone Entacmaea quadricolor on the east Australian coast

The diversity of Symbiodinium spp. in Entacmaea quadricolor was analysed from five locations along ~2,100 km on the east coast of Australia using denaturing gradient gel electrophoresis (DGGE) of the internal transcribed spacer 2 region (ITS2) combined with bacterial cloning. DGGE revealed thatE. quadricolor predominantly associated with six types of clade C (four of which are novel) and that most anemones harboured multiple types simultaneously. Anemones from southern locations associated with a mixed assemblage of C25 and a variant of C3. This assemblage also dominated the central location, but was absent at the northern location. At central and northern sites, two novel variants of C42(type2) and C1 were found. Anemones hosting C42(type2) also showed a low abundance of variants of C3 and C1, and E1 was found in one sample, as revealed by bacterial cloning. The occurrence of geographically distinct ITS2 types or a consortium of types might reflect a need to optimise physiological performance of the symbiosis at different latitudes.