Concentração de pigmentos, desempenho fotossintético e perfil de ácidos graxos em macroalgas da região de Magalhães, Chile

Abstract

The sub-Antarctic region is a biogeographic area comprising the southernmost landmass of the American continent known for its extreme environmental conditions that include, for instance, low temperatures, limited photoperiod in the winter and high exposure to ultraviolet light in summer. Physiological aspects including photosynthetic performance and chemical information such as the concentration of pigments and the lipid profile associated to the phases of development of marine macroalgae have been remotely studied. In this sense, the aim of this study was to investigate the difference of the concentration of pigments, fatty acids and photosynthetic performance in vegetative and reproductive phases of macroalgae Durvillae antarctica (Chamisso) Hariot, Lessonia flavicans Bory, Macrocystis pyrifera (Linnaeus) C. Agardh, Gigartina skottsbergii Setchell & N.L. Gardner, Iridaea cordata (Turner) Bory de Saint-Vincent and Mazzaella laminarioides (Bory) Fredericq of the Magellan region (Chile). Macroalgae were analyzed by Pulse Amplitude Modulated Fluorometry under eight irradiation conditions (11 to 490 μmol photons m -2 s -1) and pigmentation was assessed by UV/VIS Spectrophotometry (400 to 700 nm). Fatty acids (FA) extraction followed the Bligh & Dyer method (1959) and analysis was performed by Gas Chromatography Coupled to Flame Ionization Detection. Photosynthetic efficiency (α) had significant differences for L. flavicans (0.31 ± 0.01 to 0.38 ± 0.01 μmol e- m -2 s -1. μmol photons m -2 s -1) and M. pyrifera (0.26 ± 0.02 to 0.31 ± 0.03 μmol e- m -2 s -1. μmol photons m -2 s -1) for reproductive and vegetative phases, respectively. In red algae I. cordata (tetrasporophytic) and M. laminarioides (carposporophytic) values varied from 0.09 a 0.18 μmol e- m -2 s -1 . μmol photons m - 2 s -1. The relative maximum electron transfer rate (rETR max) differed significantly for brown algae in L. flavicans (8.10 ± 0.84 to 12.40 ± 1.57 μmol e- m -2 s-1) and M. pyrifera (6.49 ± 1.30 to 12.89 ± 1.53 μmol e- m -2 s-11) in distinct development phases. Saturation irradiance (Ek) analysis showed significant differences for D. antarctica(reproductive phase) varying from 166.18 ± 14.33 (vegetative) to 132.98 ± 18.43 μmol photon m-2 s-1.The highest concentrations of pigments in brown algae were found in M. pyrifera (reproductive phase) with 35.36 ± 0.21 of Chl a, 7.04 ± 0.93 of Chl c and 15.75 ± 1.42 μg g-1 of fucoxanthin. Finally in brown algae the highest concentrations of total FAs were 35.24 ± 2.38 % (saturated) and 22.02 ± 1.95 % (monounsaturated) in M. pyrifera and 63.53 ± 3.36 % (polyunsaturated) in D. antarctica. Results showed in red algae that total lipids varied between 1.25 to 2.72 % while FA classes were distributed from 23.34 to 59.93 %, 11.20 to 18.47 % and 21.60 to 65.47 % for saturated, monounsaturated and polyunsaturated FAs, respectively. The data how that differences in photosynthetic parameters, pigment concentration and fatty acid profile species are related with as habitat and development phase of the algae.