Photoinhibition of Symbiodinium spp. within the reef corals Montastraea faveolata and Porites astreoides: implications for coral bleaching

• Published in: Marine biology Vol. 158; no. 11; pp. 2515 - 2526
• Main Authors: Hennige, Sebastian J., McGinley, Michael P., Grottoli, Andréa G., Warner, Mark E.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-11-2011; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Biomedical and Life Sciences; Conservation, protection and management of environment and wildlife; Coral bleaching; Coral reefs; Corals; Dinoflagellates; Environmental degradation: ecosystems survey and restoration; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; Genetic aspects; Genotype & phenotype; Identification and classification; Influence; Life Sciences; Marine; Marine & Freshwater Sciences; Marine biology; Microbiology; Montastraea faveolata; Oceanography; Original Paper; Photochemicals; Photoinhibition; Plants; Porites astreoides; Sea water ecosystems; Symbiodinium; Synecology; Zoology; United States; United Kingdom; PSII Reaction Centre; Coral Bleaching; High Light; Electron Transport Rate; Coral Species; Protozoa; Ecological damage; Coelenterata; Cnidaria; Photoinhibition; Coral reef; Invertebrata; Scleractinia
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/s00227-011-1752-1

It is speculated that differences in coral bleaching susceptibility may be influenced by the genotype of
in hospite Symbiodinium
and their differential responses to bleaching stressors. Photoinhibition of photosystem II (PSII), damage to the D1 (psbA) PSII reaction centre protein and production of reactive oxygen species by
in hospite Symbiodinium
are likely precursors of coral bleaching. In order to assess whether photorepair rates of
in hospite Symbiodinium
underlie the bleaching susceptibility of their hosts, photoinhibition (net and gross), photoprotection and photorepair rates were assessed in a bleaching-‘tolerant’ coral (
P. astreoides
) and a bleaching-‘sensitive’ coral (
M. faveolata
) using non-invasive fluorometric techniques and by blocking de novo synthesis of psbA. Previous studies using such techniques have demonstrated that in vitro
Symbiodinium
types ‘sensitive’ to bleaching stressors had reduced rates of photorepair relative to ‘tolerant’
Symbiodinum
types. Our measurements demonstrated that
Symbiodinium
in the more bleaching tolerant
P. astreoides
had higher photorepair rates than
Symbiodinium
in
M. faveolata
. Higher repair rates in
P. astreoides
resulted in lower net photoinhibition relative to
M. faveolata
, where both corals exhibited similar susceptibility to photodamage (gross photoinhibition). Photoprotective mechanisms were observed in both corals;
M. faveolata
exhibited higher antennae-bed quenching than
P. astreoides
at low-light intensities, but at and above light-saturating intensities, which are different for each coral species,
P. astreoides
displayed more efficient non-photochemical quenching (Stern–Volmer quenching) of chlorophyll fluorescence than
M. faveolata
. Increased NPQ by
P. astreoides
at
E
/
E
k
 ≥ 1 was not driven by antennae-bed quenching. The ability of
in hospite Symbiodinium
in
P. astreoides
to mitigate the effects of photoinhibition under high light conditions compared with
Symbiodinium
in
M. faveolata
, and their high repair capacity following photoinhibition, may be a key factor to consider in future bleaching studies and may underlie the relative bleaching tolerance of
P. astreoides
compared to
M. faveolata.