Photosynthetic capacity of the endosymbiotic dinoflagellate Cladocopium sp. is preserved during digestion of its jellyfish host Mastigias papua by the anemone Entacmaea medusivora

Abstract

The sea anemone Entacmaea medusivora (Actiniaria, Anthozoa) commonly feeds on the golden jellyfish Mastigias papua (Rhizostomeae, Scyphozoa) which harbours an endosymbiotic dinoflagellate of the genus Cladocopium (Symbiodiniaceae). In this study, we monitored the photosynthetic activity of the endosymbiotic microalgae while their host jellyfish were ingested and digested by starved medusivorous anemones. By analyzing the photosynthetic yield of photosystem II, we observed that Cladocopium cells remain photosynthetically competent during the whole digestion process, thus confirming the exceptional resistance of Symbiodiniaceae to digestive enzymes. In the gastric cavity of E. medusivora, Cladocopium cells release oxygen, which could broadly stimulate the gastric microbiotic flora of the sea anemone. Ultimately, E. medusivora is not able to retain Cladocopium cells more than few days and physiologically-unaltered cells are therefore expelled in faecal pellets. The potential contribution of E. medusivora to maintain a reservoir of Cladocopium symbionts and its role in the life cycle of M. papua is discussed.

Different levels of energetic coupling between photosynthesis and respiration do not determine the occurrence of adaptive responses of Symbiodiniaceae to global warming

“…(2014) and Vega de Luna et al . (2019). Prior to measurements, cells were incubated in the dark for 15 min.…”

In vivo assessment of mitochondrial respiratory alternative oxidase activity and cyclic electron flow around photosystem I on small coral fragments

“…This so-called electrochromic shift (ECS) is a useful way to determine photosynthetic parameters such as stoichiometry of active PSI and PSII in photosynthetic eukaryotes 49 , including Symbiodiniaceae 37 . ECS spectra were determined by measuring light-absorption changes in response to 2 ms continuous illumination, each 10 nm using light band-pass filters from 480 to 600 nm, as previously described 50 .…”

Building Consensus around the Assessment and Interpretation of Symbiodiniaceae Diversity

“…However, these species numbers are likely a significant underestimate because sampling efforts have mainly focused on scleractinian coral hosts living at shallow depths in tropical and subtropical waters. It will be important to continue describing Symbiodiniaceae species in non-scleractinian hosts, including other cnidarians; e.g., octocorals (Goulet et al, 2017;Ramsby et al, 2014), zoantharians (Fujiwara et al, 2021;Mizuyama et al, 2020), actiniarians (Grajales et al, 2016), corallimorpharians (Kuguru et al, 2008), hydrocorals (Rodríguez et al, 2019), jellyfish (Vega de Luna et al, 2019); as well as sponges (Hill et al, 2011;Ramsby et al, 2017), acoelomorph flatworms (Kunihiro and Reimer, 2018), molluscs (Baillie et al, 2000;Banaszak et al, 2013;Lim et al, 2019), ciliates (Mordret et al, 2016), and foraminifera (Pochon et al, 2007). Further collections from undersampled habitats and sources such as benthic sediment and rubble (Fujise et al, 2021;Takabayashi et al, 2012), seagrasses and macroalgae (Porto et al, 2008;Yamashita and Koike, 2013), mesophotic depths (Frade et al, 2008;Goulet et al, 2019), the water column (Manning and Gates, 2008;Pochon et al, 2010), and predator feces (Castro-Sanguino and Sánchez, 2012;Grupstra et al, 2021;Parker, 1984) will likely yield many undiscovered species and possibly even novel genera (Yorifuji et al, 2021).…”