Global climate change and anthropogenic activities are threatening the future survival of coral reef ecosystems. The ability of reef-building zooxanthellate coral to survive these stressors may be determined through fundamental differences within their symbiotic dinoflagellates (Symbiodinium sp.). We define the in vitro apoptotic response of 2 evolutionarily distant Symbiodinium sp., subtypes B...

Coral reef ecosystems thrive in tropical oligotrophic oceans because of the relationship between corals and endosymbiotic dinoflagellate algae called Symbiodinium. Symbiodinium convert sunlight and carbon dioxide into organic carbon and oxygen to fuel coral growth and calcification, creating habitat for these diverse and productive ecosystems. Light is thus a key regulating factor shaping the p...

Corals at the world's southernmost coral reef of Lord Howe Island (LHI) experience large temperature and light fluctuations and need to deal with periods of cold temperature (<18°C), but few studies have investigated how corals are able to cope with these conditions. Our study characterized the response of key photophysiological parameters, as well as photoacclimatory and photoprotective pigmen...

An oxidative burst in free-living and symbiotic dinoflagellates induced by physical stress is defined and characterized. The oxidative burst occurred within 1 min of physical injury caused by short pulses of low frequency sonic sound (20 kHz, 10 s pulses). The quantities of reactive oxygen species were measured using a spectrofluorometric assay and standardized to hydrogen peroxide. Using pharm...

Like most Caribbean octocorals, Gorgonia ventalina, the common sea fan, harbors endosymbiotic dinoflagellates belonging to the genus Symbiodinium. When stressed, the host can lose these algal symbionts, a phenomenon termed "bleaching." Many cnidarians host multiple types of algal symbionts within the genus Symbiodinium, and certain types of algae may be more tolerant of stress than others. We e...

Symbiotic corals, which are benthic organisms intimately linked with their environment, have evolved many ways to deal with fluctuations in the local marine environment. One possible coping mechanism is the endogenous circadian clock, which is characterized as free running, maintaining a ~24 h periodicity of circuits under constant stimuli or in the absence of external cues. The quantity and qu...

The ability of coral reefs to recover from natural and anthropogenic disturbance is difficult to predict, in part due to uncertainty regarding the dispersal capabilities and connectivity of their reef inhabitants. We developed microsatellite markers for the broadcast spawning gorgonian octocoral Eunicea (Plexaura) flexuosa (four markers) and its dinoflagellate symbiont, Symbiodinium B1 (five ma...

The unique mutualism between corals and their photosynthetic zooxanthellae (Symbiodinium spp.) is the driving force behind functional assemblages of coral reefs. However, the respective roles of hosts and Symbiodinium in this endosymbiotic association, particularly in response to environmental challenges (e.g., high sea surface temperatures), remain unsettled. One of the key obstacles is to pro...

Genes encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were cloned from dinoflagellate symbionts (Symbiodinium spp) of the giant clam Tridacna gigas and characterized. Strikingly, Symbiodinium Rubisco is completely different from other eukaryotic (form I) Rubiscos: it is a form II enzyme that is approximately 65% identical to Rubisco from Rhodospirillum rubrum (Rubisco forms I...