Characterization of Gelidium corneum's (Florideophyceae, Rhodophyta) vegetative propagation process under increasing levels of temperature and irradiance

Climate change is affecting Gelidium corneum (Hudson) J.V. Lamouroux fields in the Bay of Biscay by reducing its cover and biomass. Understanding those changes requires a good characterization of the responses of this species to different stressors, particularly the effects on key processes such as the vegetative propagation. Here, we aimed to characterize the interactive effect of temperature (15, 20 and 25◦C) and irradiance (5-10, 55-60 and 95-100 μmol*m2*s- 1) on two phases of the vegetative propagation process: the re-attachment capacity and the survival of re-attached fragments. The study findings revealed significant effects of both temperature and irradiance in the re-attachment capacity of the species, with higher rates of attachment registered at 20 ◦C and 5-10 μmol*m- 2*s-1 after 10, 20 and 30 days of culture. However, the interaction effects were not significant at any time interval. At higher or lower temperatures and increasing irradiances, the attachment capacity was reduced. On the other hand, irradiance was demonstrated to be the main factor controlling the survival of rhizoids. In fact, higher levels of irradiance generated severe damage on rhizoids, and thus, conditioned the development of new plants. According to this, it seems clear that the vegetative propagation process of this species is expected to become more vulnerable as both variables are expected to rise due to climate change. An increased vulnerability of this species may have several implications from an ecological and economic perspective, so we encourage to continue exploring the factors and processes controlling its distribution in order to adopt better management actions in the future.

This work was funded by the National Plan for Research in Science and Technological Innovation from the Spanish Government 2017–2020 [grant number C3N-pro project PID2019-105503RB-I00] and co-funded by the European Regional Development’s funds. Samuel Sainz-Villegas and Begoña Sánchez-Astráin acknowledge the financial support received under predoctoral grants from the Spanish Ministry of Science, Innovation and Universities [grant numbers: FPU18/03573 and PRE2020-096255, respectively]. This work is part of the PhD project of Samuel Sainz-Villegas.