PHOTOACCLIMATION IN THE TROPICAL CORALLINE ALGA HYDROLITHON ONKODES (RHODOPHYTA, CORALLINACEAE) FROM A FRENCH POLYNESIAN REEF

Abstract

Pigment concentration, in vivo absorption, and photosynthetic parameters of the coralline alga Hydrolithon onkodes (Heydrich) Penrose and Woelkerling were compared among samples from a lagoon and from a reef crest of Tahiti Island. Four groups of specimens were considered, differing in their natural exposure to PAR. For specimens collected from the lagoon, the tissues from low-light samples had significantly higher pigment concentration, particularly chl a and phycobilins, compared with the highlight exposed plants that contained more total carotenoids. The in vivo absorption spectra normalized to chl a (called a* values) also revealed differences. The low-light samples had a reduced absorption capacity and a well-marked phycobilin absorption signature, whereas sunlit samples showed a greater absorption at wavelengths absorbed mainly by chl a and carotenoids. The decrease of a* when pigment concentration increased is interpreted as a consequence of the pigment packaging. Significantly lower ␣ (chlorophyll basis) and higher E k values were found in the shaded plants. The values of P max for the four groups of specimens were not significantly different. The samples showed various degrees of photoinhibition depending on the light exposure during growth, and this effect was more pronounced in the shaded plants. The specimens from the reef crest deviate from the general model presented for the lagoon samples and show a mix of sun-and shade-exposed characteristics. We have shown that the coralline alga H. onkodes responds to its light environment, probably by acclimation rather than ecotypic genetic variation, by adjusting its physiology, but some morphological differences are also involved. Photoacclimation can explain partly the wide distribution of this species over the reef ecosystem and its major contribution to the building of the reef.

Photosynthesis, respiration and calcification in the Mediterranean crustose coralline algaLithophyllum cabiochae(Corallinales, Rhodophyta)

“…Payri et al (2001) reported E k values for Hydrolithon onkodes of 110 µmol photons m −2 s −1 for specimens exposed to high light (1600 µmol photons m −2 s −1 ), reduced to 27 µmol photons m −2 s −1 for specimens exposed to lower light levels (< 200 µmol photons m −2 s −1 ). Roberts et al (2002) and Schwarz et al (2005) also reported low values of E k and E c in Arctic and Antarctic crustose corallines living at 15-20 m depth in very dim light conditions.…”

Light Absorption in Coralline Algae (Rhodophyta): A Morphological and Functional Approach to Understanding Species Distribution in a Coral Reef Lagoon

“…In coralline algae, however, the capacity of carbonate skeleton to enhance light absorption and photosynthetic performance remains unknown (see Payri et al, 2001;Burdett et al, 2014). Recently, Vásquez-Elizondo and Enríquez (2016) documented significant differences in the light absorption properties of three coralline species, before and after exposing the experimental organisms to heat-stress.…”

“…This broad taxonomic group is present in virtually every coastal ecosystem, from highly illuminated, intertidal regions to extremely light-limited habitats like rock crevices or depths of 250 m (Johansen, 1981;Littler et al, 1985;Payri et al, 2001;Burdett et al, 2014). The ecological significance of coralline algae varies from playing a fundamental role as ecosystem engineers of highly diverse communities (Foster, 2001;Steller et al, 2003) to being the preferred substrate for settlement of invertebrate larvae (Heyward and Negri, 1999;Williams et al, 2008).…”

“…The ability of coralline algae to colonize contrasting marine environments (Algarra and Niell, 1987;Häder et al, 1997;Payri et al, 2001;Schubert and García-Mendoza, 2008;Enríquez et al, 2009;Vásquez-Elizondo and Enríquez, 2016) relies on multiple physiological and structural adaptations. Among them, the optical properties of thalli may play a central role, as they are fundamental regulators of algal photosynthetic responses by controlling the entrance of solar energy.…”

The Effects of Environmental Factors on the Growth of Lithophyllum yessoense and Hildenbrandia rubra Sporelings in Laboratory Culture

“…, Hydrolithon onkodes 200-600 mol photon m -2 s -1 (Payri et al, 2001), ( , Corallina mediterranea Jania rubebs) (Hader et al, 1996). , , (canopy) (Johnson, 1984;Johnson and Mann, 1986).…”