High light alongside elevated PCO2 alleviates thermal depression of photosynthesis in a hard coral (Pocillopora acuta).
J Exp Biol
; 223(Pt 20)2020 10 21.
Article
em En
| MEDLINE
| ID: mdl-33087470
ABSTRACT
The absorbtion of human-emitted CO2 by the oceans (elevated PCO2 ) is projected to alter the physiological performance of coral reef organisms by perturbing seawater chemistry (i.e. ocean acidification). Simultaneously, greenhouse gas emissions are driving ocean warming and changes in irradiance (through turbidity and cloud cover), which have the potential to influence the effects of ocean acidification on coral reefs. Here, we explored whether physiological impacts of elevated PCO2 on a coral-algal symbiosis (Pocillopora acuta-Symbiodiniaceae) are mediated by light and/or temperature levels. In a 39â
day experiment, elevated PCO2 (962 versus 431â
µatm PCO2 ) had an interactive effect with midday light availability (400 versus 800â
µmol photons m-2 s-1) and temperature (25 versus 29°C) on areal gross and net photosynthesis, for which a decline at 29°C was ameliorated under simultaneous high-PCO2 and high-light conditions. Light-enhanced dark respiration increased under elevated PCO2 and/or elevated temperature. Symbiont to host cell ratio and chlorophyll a per symbiont increased at elevated temperature, whilst symbiont areal density decreased. The ability of moderately strong light in the presence of elevated PCO2 to alleviate the temperature-induced decrease in photosynthesis suggests that higher substrate availability facilitates a greater ability for photochemical quenching, partially offsetting the impacts of high temperature on the photosynthetic apparatus. Future environmental changes that result in moderate increases in light levels could therefore assist the P. acuta holobiont to cope with the 'one-two punch' of rising temperatures in the presence of an acidifying ocean.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Antozoários
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Exp Biol
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Estados Unidos