Dinoflagellates of the genus Symbiodinium are tied to an endosymbiotic life style with reef forming corals via a transient free-living life history phase. Newly settled larvae for many coral species must acquire their symbiont from this free-living pool; even so, surprisingly little is still known of the ecology and life history dynamics of free-living Symbiodinium. For example, how they are distributed over space and time, how they interact with their environment, and ultimately how they maintain variable populations. Therefore the overall goal of this study is to examine the distribution, abundance and functional dynamics of free-living Symbiodinium over space and time. A major knowledge gap towards this broad goal is understanding how Symbiodinium genotypes cycle through their symbiotic to free-living phases and how these dynamics are linked to the relative role of asexual (mitotic) versus sexual (meiotic) division.
Symbiodinium largely proliferate asexually by mitotic division, but evidence from other taxa suggests in sexual recombination may play an increasingly important role to persist against variable stressors. This project aims to understand the interplay between cell proliferation dynamics as Symbiodinium cycles between its symbiotic and free-living life phases, and how this may be be altered as reef systems undergo ever-changing local and climatic conditions.
Together my research activities include Symbiodinium community structure (water column, sediments, macroalgae, in hospite) and the underlying cell cycle dynamics via mitotic and meiotic division across locations (e.g. tropical versus temperate reefs) and between seasons. I will also focus on how environmental conditions and symbiont genotype select for cell cycle/life history phases and transitioning by using cultures in the laboratory, and use this data to support the complex dynamics observed in natural communities.
Fujise L, Yamashita H, Suzuki G, Koike K (2013) Expulsion of zooxanthellae (Symbiodinium) from several species of scleractinian corals: comparison under non-stress conditions and thermal stress conditions. Galaxea Journal of Coral Reef Studies. DOI 10.3755/galaxea.15.29
Fujise L, Yamashita H, Koike K (2014) Application of calcofluor staining to identify motile and coccoid stages of Symbiodinium (Dinophyceae). Fisheries Science. DOI 10.1007/s12562-013-0694-6
Fujise L, Yamashita H, Suzuki G, Sasaki K, Liao LM, Koike K (2014) Moderate thermal stress causes active and immediate expulsion of photosynthetically damaged zooxanthellae (Symbiodinium) from corals. PLoS One. DOI 10.1371/journal.pone.0114321
Oral presentation at a 6th European Phycological Congress (EPC6) entitled “Turning up the heat on Symbiodinium cell cycle analysis”; August, 2015; London, UK.