Photosynthetic metabolism and major organic compounds in the marine brown alga Desmarestia menziesii from King George Island (Antarctica)

详细信息    查看全文

• 作者：Gó ; mez ; Ivá ; n ; Weykam ; Gabriele ; Wiencke ; Christian
• 关键词：Antarctic macroalgae ; Desmarestia menziesii ; Photosynthesis ; Storage carbohydrates
• 刊名：Aquatic Botany
• 出版年：1998
• 出版时间：February, 1998
• 年：1998
• 卷：60
• 期：2
• 页码：105-118
• 全文大小：748 K

文摘

Photosynthesis and organic composition in Desmarestia menziesii from a population at Potter Cove (King George Island) were measured during the Antarctic spring-summer. Light saturated net photosynthesis (P_max), and dark respiration showed a similar seasonal variation with maximum values in plants collected in November (250 and 200 μmol O₂ g⁻¹ DW h⁻¹, respectively) and minimal values in January (42 and 16 μmol O₂ g⁻¹ DW h⁻¹, respectively). Similarly, a peak of photosynthetic efficiency (α) in November [(7.5 μmol O₂ g⁻¹ DW h⁻¹ (μmol photons m⁻² s⁻¹)⁻¹] was coupled with a peak of Chl a (6.7 mg g⁻¹ DW). Saturation points (I_k) for photosynthesis were high in January (100 μmol photon m⁻² s⁻¹) and low in December (25 μmol photon m⁻² s⁻¹), whereas compensation points (I_c) gradually decreased from 45 μmol photon m⁻² s⁻¹ in October to values close to 10 μmol photon m⁻² s⁻¹ in summer (December to February). Carbon (C) and nitrogen (N) as well as C:N ratios did not vary significantly along the study period with means close to 35 % C, 3.8 % N of dry weight and 9.3 (C:N ratio), respectively, which clearly indicates no nutrient limitation for algal metabolism. In contrast, major organic compounds showed marked seasonal changes. High protein contents close to 22 % of DW were determined in September and October, decreasing towards summer to values of 12 % of DW, whereas total amino acids (free and protein-bound) had a peak in November (18 % of DW) and remained low between December and February (below 12 % of DW). Mannitol content was relatively low between September and December increasing to values close to 8 % of DW in February. Laminaran was high in September (7.2 % of DW) and remained low and relatively constant (ca. 2.5 % of DW) from October onwards. The significant effect of amino acids, mannitol, laminaran, protein contents inferred from regression analyse point up to a relationship between monthly allocation of organic compounds and high metabolic activities during spring-summer, i.e., reserve carbohydrates may compensate, at least partially, for C losses due to the high respiratory activity.