Paper| Year: | 2017 |
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| Author(s): | J. Marambio, J.P. Rodriguez, F. Mendez, P. Ocaranza, S. Rosenfeld, J. Ojeda, R. Rautenberger, K. Bischof, J. Terrados, A. Mansilla |
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| Title: | Photosynthetic performance and pigment composition of Macrocystis pyrifera (Laminariales, Phaeophyceae) along a gradient of depth and seasonality in the ecoregion of Magellan, Chile. |
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| Journal: | JOURNAL OF APPLIED PHYCOLOGY |
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| ISSN: | 0921-8971 |
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| JCR Impact Factor: | 2.401 |
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| Volume: | 29 |
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| Issue No.: | 5 |
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| Pages: | 2575-2585 |
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| D.O.I.: | 10.1007/s10811-017-1136-0 |
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| Web: | https://doi.org/10.1007/s10811-017-1136-0 |
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| Abstract: | Macrocystis pyrifera (L.) C. Agardh
is a species that forms extensive underwater forests along the
coastline of the ecoregion of Magellan. There, this alga is exposed to
marked variation in photoperiod, temperature, and irradiance, which are
modulated by daily and seasonal climatic variations. This study aims to
understand the ecophysiological behavior of M. pyrifera,
in a natural forest localized in Puerto del Hambre, Magellan Region of
Chile, along spatial (depth) and temporal (season) gradients of physical
drivers by analyzing algal responses in terms of the photosynthetic
pigments and fluorescence yield. In the apical, middle, and basal
fronds, the following photosynthetic parameters were seasonally
measured: electron transport efficiency (α), maximum relative rate of electron transport (rETRmax), saturation point (Ek), and pigments such as chlorophyll a (Chl a), chlorophyll c (Chl c), and fucoxanthin. Both seasonal and stratified variations were observed. In autumn, α was decreased in the middle fronds (0.136 ± 0.030 (μmol photons m−2 s−1)−1) with respect to apical and basal fronds of autumn. For parameters such as Ek, this decrease was observed relative to the depth gradient, with significant differences (p < 0.05) between distinct fronds. rETRmax was high in the apical fronds in spring, autumn, and winter. High Chl a concentration was maintained in all seasons, while the concentration of Chl c
in the apical fronds tended to be lower. The concentration of
fucoxanthin remained stable without significant differences between
dissimilar types of fronds, for seasons (spring, summer, autumn, and
winter). The Chl a/Chl c ratio increased with depth, while the Chl a/fucoxanthin
ratio varies seasonally. Variations of light intensity in a natural
population in a depth gradient and pigment variations in M. pyrifera with the depth stratification reveal the behavior of these algae in the ecoregion of Magellan where Chl a,
through the apical fronds, could be regulating the photosynthetic
activity of the plants at stratification level. Furthermore, the
increase in Chl c and fucoxanthin towards the middle and basal fronds showed similar trends as those measured for α,
thus signifying higher photosynthetic efficiency at greater depth.
Overall, our results indicate marked seasonal and depth acclimation to
different environmental conditions. This study is the first of its kind
for the ecoregion of Magellan in which M. pyrifera represents a keystone species of utmost ecological significance. |
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Related staffJorge Terrados MuñozRelated research groupsMarine Ecosystems Dynamics
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