Phenology and photosynthetic performance of Porphyra spp. (Bangiophyceae, Rhodophyta): Seasonal and latitudinal variation in Chile

• Phenology and photosynthetic performances described for the red macroalgae Porphyra.
• Seasonal changes according to radiation were detected in the studied populations.
• Latitudinal changes according to temperature were detected for the studied populations.
• Four different morphotypes were detected in the studied populations.

Phenological studies attempt to understand the seasonal development of organisms in response to environmental variations. Seaweeds can respond (1) as a “seasonal anticipator” with growth occurring due to specific triggers and (2) as a “seasonal responder”, with growth and photosynthesis occurring during more favorable conditions. Porphyra C. Agardh is an ecophysiologically successful genus that occurs in the uppermost rocky intertidal zone due to its biochemical and physiological traits. In Chile, Porphyra is distributed throughout all rocky shores (20–56° S), with at least five types of morphological strains and a still unclear taxonomic status. The phenology (cover, biomass, reproductive porcentage) and photosynthetic performance (ETR–light curves) were studied along a seasonal (winter 2010–winter 2011) and latitudinal gradient (25–34° S) in order to characterize the populations and promote their utilization for human food. Four different morphotypes were detected within the studied populations. Seasonal and latitudinal variations of the environment determined the phenological and ecophysiological responses of Porphyra spp. A decline in algal abundance, reproductive potential and photosynthetic performance during warm periods and from southern toward northern latitudes was observed. In a seasonal context, variation in temperature and irradiance can be crucial for the phenological and ecophysiological responses of Porphyra, whereas in a latitudinal context, temperature appeared to be more relevant. Most of the patterns observed, probably occurred due to biochemical and physiological traits. Studies on a seasonal and latitudinal scale might enhance the management and use of Porphyra as human food.