Decadal environmental ‘memory’ in a reef coral?

Abstract

West sides of the coral Coelastrea aspera, which had achieved thermo-tolerance after previous experience of high solar irradiance in the field, were rotated through 180o on a reef flat in Phuket, Thailand (7o50´N, 98o25.5´E), in 2000 in a manipulation experiment and secured in this position. In 2010, elevated sea temperatures caused extreme bleaching in these corals, with former west sides of colonies (now facing east) retaining four times higher symbiont densities than the east sides of control colonies, which had not been rotated and which had been subject to a lower irradiance environment than west sides throughout their lifetime. The reduced bleaching susceptibility of the former west sides in 2010, compared to handling controls, suggests that the rotated corals had retained a ‘memory’ of their previous high irradiance history despite living under lower irradiance for 10 years. Such long-term retention of an environmental ‘memory’ raises important questions about the acclimatisation potential of reef corals in a changing climate and the mechanisms by which it is achieved

Coral microbiome diversity reflects mass coral bleaching susceptibility during the 2016 El Niño heat wave

“…Alternate host-symbiont associations were observed among the coral taxa that exhibited comparatively little mass bleaching within CMNP, P. lutea and C. aspera. As with elsewhere in Eastern Africa (Chauka, 2012), the Red Sea and Persian-Arabian Gulf Smith, Vaughan et al, 2017;Ziegler, Eguíluz et al, 2017a) types in Western Australia (Silverstein, Correa, LaJeunesse, & Baker, 2011), and D1a types in Thailand (Brown, Dunne, Edwards, Sweet, & Phongsuwan, 2015). Thermally tolerant D. trenchii (ITS2 type profile D1-4 is routinely observed in the WIO with a wide host range and where more than one Symbiodiniaceae type is detected within a coral species (LaJeunesse et al, 2010;see alsoSmith, Ketchum et al, 2017;Smith, Vaughan et al, 2017).…”

“…As with elsewhere in Eastern Africa (Chauka, ), the Red Sea and Persian‐Arabian Gulf (Smith, Ketchum et al, ; Smith, Vaughan et al, ; Ziegler, Eguíluz et al, ) and Pacific (e.g., LaJeunesse et al, ; LaJeunesse et al, ), P. lutea in the CMNP almost exclusively associated with ITS2 type C15. Perhaps most intriguingly was the high diversity of Symbiodiniaceae in C. aspera (formerly known as Goniastrea aspera —see Huang et al, ) comprising predominantly D1–D4 (–D6) ITS2 type profiles, in comparison to previously being associated with C3 types in the Indian Ocean (LaJeunesse et al, ), C1 types in Western Australia (Silverstein, Correa, LaJeunesse, & Baker, ), and D1a types in Thailand (Brown, Dunne, Edwards, Sweet, & Phongsuwan, ). Thermally tolerant D. trenchii (ITS2 type profile D1–4 is routinely observed in the WIO with a wide host range and where more than one Symbiodiniaceae type is detected within a coral species (LaJeunesse et al, ; see alsoSmith, Ketchum et al, ; Smith, Vaughan et al, ).…”

High-frequency temperature variability mirrors fixed differences in thermal limits of the massive coralPorites lobata(Dana, 1846)

“…Corals are long-lived organisms, and based on the size (>1 m diameter) of the colonies used in this study, we roughly estimate the minimum age of the source colonies to be >60 years old (based on >500 mm radius and ∼8 mm year -1 growth rate sensu Houck et al, 1977;Potts et al, 1985). Decadal-scale 'environmental memory' was recently observed in the massive coral Coelastrea aspera, with former west sides of colonies (experimentally turned to face east) that had been previously exposed to high-irradiance levels retaining four times the D. trenchii during a natural bleaching event compared with unmanipulated eastfacing/low-irradiance sides of colonies, despite 10 years of conditioning to the low-irradiance eastern orientation and identical D. trenchii species/phylotypes (Brown et al, 2015). This certainly raises the possibility that long-term conditioning to the high-frequency environmental variability of the Ofu back reef could have long-lasting acclimation effects on P. lobata thermal tolerance limits that may not have been altered by our 36-day exposure.…”

High-frequency temperature variability mirrors fixed differences in thermal limits of the massive coralPorites lobata(Dana, 1846)

“…Corals are long-lived organisms, and based on the size (>1 m diameter) of the colonies used in this study, we roughly estimate the minimum age of the source colonies to be > 60 years old (based on > 500 mm radius and ∼8 mm/year growth rate sensu Houck et al, 1977; Potts et al, 1985). Decadal-scale ‘environmental memory’ was recently observed in the massive coral Coelastrea aspera , with former west sides of colonies (experimentally turned to face east) that had been previously exposed to high-irradiance levels retaining four times the Symbiodinium during a natural bleaching event compared to un-manipulated east-facing/low-irradiance sides of colonies; despite 10 years of conditioning to the low-irradiance eastern orientation and identical Symbiodinium phylotypes (Brown et al, 2015). This certainly raises the possibility that long-term conditioning to the high-frequency environmental variability of the Ofu back-reef could have long-lasting acclimation effects on P. lobata thermal tolerance limits that may not have been altered by our 36-day exposure.…”