Environmental Drivers of Phlorotannin Variability in the macroalga Alaria esculenta (Phaeophyceae). Insights from Wild Populations, Aquaculture and Laboratory Studies
Authors
Ralf Rautenberger (presenting author) [1]
Michael Streicher [1]
Léo Minini [1]
Sara Roosvall [1]
Sdena Nunes [1]
Oddvar Ottesen [2]
Keywords
Brown Macroalgae; Marine Polyphenols; Abiotic Stress; Kelp Cultivation; High-Latitude Ecology; Bioactive Compounds
Abstract
Brown macroalgae contain a great variety of unique polyphenolic compounds, the phlorotannins, which are based on phloroglucinol subunits. The polyphenolic compounds possess numerous biological functions, ranging from eco-physiological response to environmental stress and structural cell integrity to novel biotechnological applications.
While algae of the taxonomic order Fucales are characterised by high phlorotannin contents, Laminariales are generally known for their low concentrations. However, Alaria esculenta from Northern Norway, a member of the Laminariales, seems to be an exemption. It demonstrated a significant variability in its phlorotannin contents and associated antioxidant performance. This presentation compiles results from several integrated projects. First, we examine the spatial and temporal differences in phlorotannin levels and antioxidant capacities across wild-grown populations and seasons in Northern Norway. Second, given the commercial importance of A. esculenta to the Norwegian aquaculture industry, we present data from professional cultivation sites near Bodø to understand eco-physiological stress responses and optimize harvest timing. Finally, laboratory stress experiments were conducted to identify the primary environmental drivers—such as irradiance, UV radiation, salinity, and temperature—that trigger phlorotannin accumulation.
This research provides a better understanding of the previously unexpected variability of phlorotannins in A. esculenta. These insights are not only of ecological interest regarding the alga’s stress management in its natural habitat but also play a critical role in the commercial production of phlorotannins and the blue economic development of Northern Norway.
Funding
- MABIT, Antioxidants of brown and red marine macroalgae as potential new preservatives for freshly caught Atlantic cod (Gadus morhua) from Northern Norway (MacroCod), grant BS0083, granted to RR
- Arktis 2030 - main project (Troms og Finnmark fylkeskommune), Valorisation of marine macroalgae for the industrial development in North Norway (MacVal), grant 384/23, granted to RR and OO