Littoral phytobenthos of the largest Ιtalian lake (L. Garda), with focus on the adaptive traits of the rhodophyte Bangia atropurpurea in relation to water-level-fluctuations-related stressors

The ACE_SAP Project, funded by the Autonomous Province of Trento (Italy), considers a diverse set of organisms with the aim to gain a thorough understanding of adaptive traits of selected species to climate-change-sensitive stressors. We selected Bangia atropurpurea, that grows on rocks in the water-level fluctuation zone of Lake Garda. The goal is to understand its main adaptive traits in relation to high irradiance (UV) exposure and desiccation, from the ecological, bioorganic, morphological, and ecogenomic point of view. The study of the seasonality of this macroalga, of its interactions with the other main macroscopic algae (cyanoprokaryota), and of its exact location with respect to the water level started in February 2008. Epiphytic diatoms growing on B. atropurpurea were studied in detail: 51 taxa were identified, the most frequent and abundant being Cocconeis pediculus and Diatoma ehrenbergii. Interesting spatial and temporal trends were highlighted: Diversity of epiphytic diatoms was found to be strongly correlated to the development of the host alga. In parallel to the study of the distribution of B. atropurpurea along the shores of the whole lake, epilithic diatoms were sampled from 24 stations (including impacted and non-impacted areas). A first comparison between epilithon and epiphytes will be provided.