Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism

Daylength is the major environmental factor affecting the seasonal photosynthetic performance of Antarctic macroalgae. For example, the "season anticipation" strategy of large brown algae such as Ascoseira mirabilis and Desmarestia menziesii are based on the ability of their photosynthetic...

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Autor principal:	GÓMEZ,I.
Lenguaje:	English
Publicado:	Sociedad de Biología de Chile 2001
Materias:	polar macroalgae Antarctic photosynthesis daylength
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000200004
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spelling	oai:scielo:S0716-078X20010002000042001-11-08Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolismGÓMEZ,I. polar macroalgae Antarctic photosynthesis daylength Daylength is the major environmental factor affecting the seasonal photosynthetic performance of Antarctic macroalgae. For example, the "season anticipation" strategy of large brown algae such as Ascoseira mirabilis and Desmarestia menziesii are based on the ability of their photosynthetic apparatus to make use of the available irradiance at increasing daylengths in late winter-spring. The seasonal development and allocation of biomass along the lamina of A. mirabilis are related to a differential physiological activity in the plant. Thus, intra-thallus differentiation in O2-based photosynthesis and carbon fixation represents a morpho-functional adaptation that optimizes conversion of radiant energy to primary productivity. In Desmarestia menziesii, reproductive phases show different photosynthetic characteristics. Small gametophytes and early stages of sporophytes, by virtue of their fine morphology, have a high content of pigments per weight unit, a high photosynthetic efficiency, very low light requirements for photosynthesis, and they are better suited to dim light conditions than adult sporophytes. This strategy ensures the completion of the life-cycle under seasonally changing light conditions. Low light requirements for growing and photosynthesizing are developed to cope with Antarctic seasonality and constitute adaptations to expand depth zonation of macroalgae. No differences in net Pmax and photosynthetic efficiency (a) among algae growing at depths between 10 and 30 m, suggest a low potential for photoacclimation enabling algae to grow over a wide range of prevailing light conditions. However, shortenings in the daily period during which plants are exposed to saturation irradiances for photosynthesis (Hsat) and low carbon balance (daily P/R ratios) at depths close to or larger than 30 m negatively affect primary productivity. In general, photosynthetic rates of Antarctic macroalgae at 0 °C are comparable to those measured in species from temperate and cold-temperate regions. This clearly indicates a major physiological adaptation to the polar environmentinfo:eu-repo/semantics/openAccessSociedad de Biología de ChileRevista chilena de historia natural v.74 n.2 20012001-06-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000200004en10.4067/S0716-078X2001000200004
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	polar macroalgae Antarctic photosynthesis daylength
spellingShingle	polar macroalgae Antarctic photosynthesis daylength GÓMEZ,I. Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism
description	Daylength is the major environmental factor affecting the seasonal photosynthetic performance of Antarctic macroalgae. For example, the "season anticipation" strategy of large brown algae such as Ascoseira mirabilis and Desmarestia menziesii are based on the ability of their photosynthetic apparatus to make use of the available irradiance at increasing daylengths in late winter-spring. The seasonal development and allocation of biomass along the lamina of A. mirabilis are related to a differential physiological activity in the plant. Thus, intra-thallus differentiation in O2-based photosynthesis and carbon fixation represents a morpho-functional adaptation that optimizes conversion of radiant energy to primary productivity. In Desmarestia menziesii, reproductive phases show different photosynthetic characteristics. Small gametophytes and early stages of sporophytes, by virtue of their fine morphology, have a high content of pigments per weight unit, a high photosynthetic efficiency, very low light requirements for photosynthesis, and they are better suited to dim light conditions than adult sporophytes. This strategy ensures the completion of the life-cycle under seasonally changing light conditions. Low light requirements for growing and photosynthesizing are developed to cope with Antarctic seasonality and constitute adaptations to expand depth zonation of macroalgae. No differences in net Pmax and photosynthetic efficiency (a) among algae growing at depths between 10 and 30 m, suggest a low potential for photoacclimation enabling algae to grow over a wide range of prevailing light conditions. However, shortenings in the daily period during which plants are exposed to saturation irradiances for photosynthesis (Hsat) and low carbon balance (daily P/R ratios) at depths close to or larger than 30 m negatively affect primary productivity. In general, photosynthetic rates of Antarctic macroalgae at 0 °C are comparable to those measured in species from temperate and cold-temperate regions. This clearly indicates a major physiological adaptation to the polar environment
author	GÓMEZ,I.
author_facet	GÓMEZ,I.
author_sort	GÓMEZ,I.
title	Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism
title_short	Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism
title_full	Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism
title_fullStr	Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism
title_full_unstemmed	Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism
title_sort	ecophysiology of antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism
publisher	Sociedad de Biología de Chile
publishDate	2001
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2001000200004
work_keys_str_mv	AT gomezi ecophysiologyofantarcticmacroalgaeeffectsofenvironmentallightconditionsonphotosyntheticmetabolism
_version_	1718439504068476928

Ecophysiology of Antarctic macroalgae: effects of environmental light conditions on photosynthetic metabolism

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