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

Abstract

Primary production and calcification responses to irradiance were investigated in Lithophyllum cabiochae, a crustose coralline alga from Mediterranean coralligenous communities, collected at c. 25 m depth in the Bay of Villefranche. Algae were maintained in aquaria at temperature and irradiance levels close to in situ conditions. Physiological measurements were performed using incubation chambers in the dark and in the light at different irradiance levels within the range of those measured in situ. Both photosynthesis and calcification rates in L. cabiochae were strongly related to irradiance. Dark respiration averaged 0.2-0.3 µmol cm −2 thallus h −1 in terms of both O 2 consumption and CO 2 release and maximal gross photosynthesis averaged 1.0 µmol cm −2 h −1 in terms of both O 2 production and CO 2 uptake. Mean rate of net calcification was 0.1 µmol CaCO 3 cm −2 h −1 in the dark and reached 0.4 µmol CaCO 3 cm −2 h −1 in the light. Diel net and gross organic C productions were estimated to be 3 and 7 µmol C cm −2 thallus d −1, respectively. Diel net inorganic C production was estimated to be 3 µmol CaCO 3 cm −2 thallus d −1. Despite the low light conditions experienced by the algae at c. 25 m depth, L. cabiochae can be considered as a major contributor to primary productivity and calcium carbonate deposition, making coralligenous communities a major carbon and carbonate producer in the Mediterranean Sea.

In situ changes of tropical crustose coralline algae along carbon dioxide gradients

“…The declines in CCA cover in response to CO 2 were steeper on these shaded bottom-sides compared to the top-sides of the tiles, suggesting that CCA may be physiologically more vulnerable to high CO 2 in low compared to high light environments. Previous physiological studies have shown that some CCA can continue to grow at high CO 2 in high light environments, but suffer dissolution in the dark2930. Our data also show the need for high light to maintain populations at high CO 2 in the field, with day-time calcification offsetting potential night-time dissolution.…”

Coralligenous and maërl habitats: predictive modelling to identify their spatial distributions across the Mediterranean Sea

“…They are the result of the building activities of algal and animal constructors, counterbalanced by physical, as well as biological, eroding processes. Because of their extent, biodiversity and production, coralligenous and maërl habitats rank among the most important ecosystems in the Mediterranean Sea [17][18][19][20][21] , and they are considered of great significance both for fisheries 22 and carbon regulation 23,24 .…”

Mediterranean Lithophyllum stictiforme (Corallinales, Rhodophyta) is a genetically diverse species complex: implications for species circumscription, biogeography and conservation of coralligenous habitats

“…Based on the color and habit of the material illustrated, the material used by Martin et al. (,b; as L. cabiochiae ) appears to be L. stictiforme (clade 1). Conversely, the thalli depicted by Garrabou and Ballesteros () cannot be reliably identified.…”