Physiology of maerl algae: Comparison of inter‐ and intraspecies variations

Free-living red coralline algae play an important role in the carbon and carbonate cycles of coastal environments. In this study, we examined physiology free-living algae-forming maerl beds Bay Brest (Brittany, France), where Lithothamnion corallioides is dominant (i.e., rhodolith) species. Phymatolithon calcareum Lithophyllum incrustans are also present (in lower abundances) at a specific site bay. We aimed to assess how affected by seasonality and/or local environmental variations inter- intraspecific levels. Physiological measurements (respiration, photosynthetic, calcification rates) were performed using incubation chambers winter summer compare (1) species three sites (2) coexisting one site. Comparison suggests that L. best adapted current conditions Brest, because most robust dissolution dark has highest efficiency light. Comparisons metabolic rates between stations showed morphological within main factor affecting its photosynthetic rates. Environmental factors such as freshwater inputs affect dark. addition interspecies variation physiology, there associated with direct (water physico-chemistry) or indirect (morphology) conditions. This study demonstrates plasticity response changes, which fundamental for persistence.