Heat stress destabilizes symbiotic nutrient cycling in corals

Repair machinery of symbiotic photosynthesis as the primary target of heat stress for reef-building corals.

In a coral-algae symbiotic system, heat-dependent photoinhibition of photosystem II (PSII) leads to coral bleaching. When the reef-building coral Acropora digitifera was exposed to light, a moderate increase of temperature induced coral bleaching through photobleaching of algal pigments, but not through expulsion of symbiotic algae. Monitoring of PSII photoinhibition revealed that heat-dependen...

Photosynthesis and photoprotection in symbiotic corals

In zooxanthellate corals, excess excitation energy can be dissipated as heat (nonphotochemical quenching), thereby providing protection against oxidative damage by supraoptimal light in shallow reefs. To identify and quantify the photoprotective mechanisms, we studied the diel variability of chlorophyll fluorescence yields and photosynthetic parameters in situ in corals, using moored and SCUBA-...

Interactions between Corals and their Symbiotic Algae

Interactions between Corals and their Symbiotic Algae Gisèle Muller-Parker and Christopher F. D'Elia The mutualistic relationship between corals and their algal endosymbionts is a key factor in the evolutionary success of hermatypic (reef building) corals. Corals that harbor endosymbiotic algae exhibit faster rates of calcification, photoautotrophy and many other attributes that are believed to...

Nutrient Relationships: Cycling

Nutrient Relationships: Cycling

Figure 1. Nutrients may be tied up in bryophytes for decades, or recycle within months, in forests with abundant bryophytes, as in this forest with Isothecium myosuroides. Photo by Michael Lüth. Few quantitative studies have addressed the role of bryophytes in ecosystem nutrient cycling. Nevertheless, bryophytes may play a significant role in N retention and release in the ecosystem (Figure 1)....