Short-term effects of heavy metal and temperature stresses on the photophysiology of Symbiodinium isolated from the coral Fungia repanda

Abstract

Ghoora MD, Pilly SS, Chumun PK, Jawaheer S, Bhagooli R. 2017. Short-term effects of heavy metal and temperature stresses on the photo-physiology of Symbiodinium isolated from the coral Fungia repanda. Ocean Life 1: 11-20. This study aimed to investigate the effects of the heavy metals, copper, zinc and lead, on the photo-physiology of the symbiotic dinoflagellate Symbiodinium isolated from the coral Fungia repanda. Freshly isolated Symbiodinium found to belong to clade C were exposed to different concentrations of the three heavy metals for 3-hour and 18-hour treatments at 28°C and 32°C. The Pulse Amplitude Modulated (PAM) fluorometry technique was used to determine the maximum quantum yield (Fv/Fm), relative maximum electron transport rate (rETRmax) and maximum non-photochemical quenching (NPQmax) of the photosystem II (PSII). An increase in non-photochemical quenching accompanied by a decrease in photosynthetic capacity was noted for copper at a concentration of 50 µg/L for both temperatures. The Fv/Fm was not significantly affected by the Zn treatments. However, at 28 °C, isolates treated with 100 µg/L Zn for 18 hours showed an increase in non-photochemical quenching accompanied by a decrease in photosynthetic capacity. Pb had the most profound effect on all of the isolates. The Fv/Fm significantly decreased and an increase in NPQmax was noted. The decrease of rETRmax and increase in NPQmax for the heavy metal bioassays under 32 °C were more significant than at 28 °C. This study suggests that Cu (≥50 µg/L), Zn (≥ 100 µg/L) and Pb decrease the photosynthetic capacity of the Symbiodinium isolates from F. repanda especially more so with increasing temperatures.

Differential photo-physiological responses of two giant clam species to elevated temperature stress from Rodrigues Island, Western Indian Ocean

“…Genetic clades of Symbiodiniaceae have unique physiological characteristics (Rowan et al 1997;Tchemov et al 2004;Sampayo et al 2008;Bhagooli 2009Bhagooli , 2010Ghoora et al 2018;Mattan-Moorgawa et al 2020) which may play a big role in the host's survival affinity and its susceptibility to environmental stresses and changes (Baker 2001). Giant clams are known to host Symbiodiniaceae of clades A, C and D only or a mixture of these clades (Baillie et al 2000 a,b;DeBoer et al 2012).…”

Variable thermal and biochemical stress responses of tissue balls from <i>Lithophyllon repanda, Pocillopora damicornis</i> and <i>Acropora muricata</i>

“…These observations can be explained by the fact that A. muricata colonies harbour clade Alike Symbiodinium (Louis et al 2016a), which might confer enhanced acclimatization capacity. Acclimatization capacity can be in terms of photophysiological (Louis et al 2016b), antioxidant and Hsp70 (Louis et al 2020) (Ghoora et al 2018) have also experi men tally indicated variable responses. These studies suggest that Mauritian corals exhibit differential bleaching re sponses.…”