Galaxea, Journal of Coral Reef Studies Vol. 18(2016) No. 1

Populations of once dominant reef building coral Acropora clathrata in Arabian Gulf is declining, mainly due to thermal bleaching and anthropogenic factors such as rapid urbanization, toxic wastes, destructive fishing practices, land reclamation and sedimentation. To actively restore coral populations, continuous supply of corals is required without causing damage to the existing reefs. In this study, as part of the coral gardening approach, mid water coral nurseries were constructed in Abu Al Abyad Island, United Arab Emirates following the coral tree nursery model. Six hundred fragments, with an average length of 6.32cm (SD ±1.23cm) of Acropora clathrata were mounted in the nursery and reared for 21 months while monitoring the health of the fragments continuously and estimating the growth rate and survivorship of the corals every three months. Only 9.8% of mortality was recorded in the entire study period, while a linear growth rate of 6.44cm･year^－1 (SD ±0.72) was achieved in the first 12 months and 9.25cm･year^－1 (SD ±0.63) in the remaining 9 months. Almost negligible mortality and satisfactory growth of corals during the entire nursery period suggest that the coral tree nursery model is suitable for propagating A. clathrata in Arabian Gulf.

The dinoflagellate genus Symbiodinium consists of well-known coral symbionts. The genus is divided into nine phylogenetically distinct groups (clades A-I), with each consisting of numerous small groups (types or sub-clades). Some Symbiodinium can be isolated from host animals and maintained as culture strains under laboratory conditions, but there is currently very little biological information on cultured Symbiodinium. In the present study, we observed motility and cell division patterns in eight Symbiodinium culture strains for clades A-F. Al-though cell division patterns were congruent among all of the culture strains, their motility patterns differed. Peak cell division was observed at dawn in all of the cultures. The ratio of motile phase cells declined at night, but in clade A type A2 relative and clade E Symbiodinium culture strains, which were isolated from the environment, >10% of the cells actively swam at night. While we only investigated eight cultures, we observed similarities and differences in their characteristics. Although several Symbiodinium are difficult to cultivate, future studies on cultured cells would give better insights into the biology of Symbiodinium spp.