Effect of thermal stress on physiological responses, chemical composition and antioxidant potential of Sargassum stenophyllum (Fucales, Ochrophyta) and Pyropia spiralis (Bangiales, Rhodophyta).

Author(s)

Vanessa Urrea Victoria

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB)
• Defense date: 2018-11-22

Examining board members

Fanly Fungyi Chow Ho; José Bonomi Barufi; Flavia Marisa Prado Saldanha Correa; Fosca Pedini Pereira Leite; Estela Maria Plastino

• Advisor: Fanly Fungyi Chow Ho

Abstract

Temperature fluctuations in the marine environment, due to natural processes and anthropogenic activities, caused by tidal fluctuation, cooling of energy power plants, and global warming affect the ecological dynamics and physiological responses of marine organisms, mainly in benthic macroalgae. Seaweeds inhabiting the boundaries of the intertidal zone may be subjected to strong short-term temperature variations, such as Sargassum and Pyropia. On this perspective, the aim of this project was to provide subsidies for understand the effect of temperature and the mechanisms of tolerance and sensitivity of the intertidal species Sargassum stenophyllum (Fucales, Ochrophyta) and Pyropia spiralis (Bangiales, Rhodophyta) from São Paulo, through the analysis of photosynthetic performance, chemical variation, and antioxidant responses, as well as, to provide information about its potential as functional product. The responses of the studied seaweeds were evaluated under temperatures of 15, 20, 25 (control), 30 and 35 °C over seven days in laboratory controlled conditions. The species displayed similar proportions in energy dissipation and growth rate, and few changes in the chemical profile (e.g. pigments, carbohydrates, carotenoids, and amino acids) between 15 and 30 ºC, which can be identificated as thermal tolerance range. In contrast, algae were sensitive at 35 ºC, with decrease in photosynthesis and growth since the third day of the experimental period. Under high temperature, above 30 °C, S. stenophyllum phylloids and P. spiralis thalli might have released chemical compounds, such as phenolic compounds, evidenced by color change of the seawater. Under low temperature condition (15 °C), P. spiralis showed accumulation of mycosporin-like amino acids. In general, the studied species are promising as a functional product involved in the feed area due to its nutritional composition and antioxidant properties (AU)

• FAPESP's process: 14/25073-3 - Studies of the effect of heat stress on physiological responses, chemical composition and antioxidant activity of Pyropia spiralis E. C. Oliveira & Coll (Bangiales, Rhodophyta) and Sargassum filipendula C. Agardh (Fucales, Phaeophyceae)
• Grantee: Vanessa Urrea Victoria
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)