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Seasonal Growth and Photosynthetic Performance of the Antarctic Macroalga Desmarestia menziesii (Phaeophyceae) Cultivated under Fluctuating Antarctic Daylengths
Author(s) -
Gömez I.,
Wiencke C.
Publication year - 1997
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1997.tb00607.x
Subject(s) - photosynthesis , sporophyte , chlorophyll a , botany , biology , algae , respiration rate , respiration , seasonality , phenology , chlorophyll , light intensity , photosynthetic pigment , horticulture , ecology , physics , optics
Growth, photosynthesis, dark respiration and pigment contents were monitored in adult sporophytes of the Antarctic brown alga Desmarestia menziesii J. Agardh grown under fluctuating Antarctic daylength conditions. Growth rates were closely coupled to daylength variations with values varying from 0.05% d −1 in winter condition (July‐August) to 0.5% d −1 in early summer (December). Photosynthetic pigments had maximum values of 1.8 mg g −1 FW (chlorophyll a) , 0.4 mg g −1 FW (chlorophyll c) and 0.9 mg g −1 FW (fucoxanthin) in summer. These changes were also closely related to individual size and biomass of the plants. Net photosynthesis (P max ), on a fresh weight basis, showed a clear seasonal pattern with highest rates of 25μmol O 2 g −1 FW h −1 in October and minima close to 9μmol O 2 g −1 FW h −1 in April. Dark respiration was high in spring (13μmol O 2 g −1 FW h −1 ) approximately coinciding with growth peaks. Likewise, photosynthetic efficiency (α) and the initial saturating light point of photosynthesis (l k ) increased significantly in spring [1.3 μimol O 2 g −1 FW h −1 (μmol m −2 s −1 ) −1 and 26μmol photons m −2 s −1 , respectively]. In the case of α, no significant differences between fresh weight and Chl a based rates were found. The results of the present study are the first that demonstrate seasonality of physiological parameters in D. menziesii sporophytes and confirm also that phenology and physiology of macroalgae can be simulated in the laboratory. On the other hand this study adds new elements to the explanation of the life strategy of D. menziesii , in particular that algal growth and photosynthesis occur under a programmed seasonal pattern.