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SEASONAL VARIATIONS OF PHOTOSYNTHETIC PIGMENTS, TOTAL C, N, AND P CONTENT, AND PHOTOSYNTHESIS IN PHYLLARIOPSIS PURPURASCENS : (PHAEOPHYTA) FROM THE STRAIT OF GIBRALTAR
Author(s) -
FloresMoya Antonio,
Fernández José A.,
Xavier Niell F.
Publication year - 1995
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.1995.00867.x
Subject(s) - photosynthesis , biology , zoology , botany , population , pigment , chlorophyll a , respiration rate , chlorophyll , respiration , saturation (graph theory) , dry weight , photosynthetic pigment , horticulture , chemistry , demography , mathematics , organic chemistry , combinatorics , sociology
Photosynthetic pigments, C, N, and P tissue composition, and photosynthetic rate were measured from April to October in the brown alga Phyllariopsis purpurascens ( C. Agardh) Henry et South (Laminariales, Phaeophyta) growing at a 30‐m depth in the Strait of Gibraltar. Ir‐radiance reaching the population ranged from 13.5 to 27.5 mol.m ‐2 .mo ‐1 . The available light for this species, expressed as a percentage of the irradiance above the water, was 1.8%. Dissolved inorganic nitrogen forms, NO3‐and NH 4 +, were constant from April to October, whereas phosphate was depleted in August. Chlorophyll a decreased from 520.0 ± 165.0 to 199.6 ± 159.9 μg.g ‐1 dry weight; in contrast, chlorophyll c and carotenoids did not change until September but increased threefold in October. C:N and N:P ratios changed in the same way and in the same range. They were constant until July but increased from 15–17 up to 42 (C:N) and from 14 to 40 (N:P) in October, suggesting a severe P limitation of growth of this species. The dark respiration rate and the light compensation point were constant from April to October (0.5 ± 0.1 μmol O 2 . m ‐2. s ‐1 and 6.5 ± 0.2 μmol.m ‐2. s ‐1 , respectively), whereas the maximum rate of apparent photosynthesis, light onset saturation parameter, and half saturation constant for light were maximum in April to May (3.7 μmol O 2 . m ‐2. s ‐1 and 40 and 41.5 μmol.m ‐2 . s ‐1 , respectively) and October (3.6 μmol O 2 . m ‐2. s ‐1 and 50 and 53.7 μmol.m ‐2 . s ‐1 , respectively). They were minimum in August (1.2 μmol O 2 .m ‐2. s ‐1 and 11.3 and 12 μmol.m ‐2. s ‐1 , respectively). These minimum figures yielded a negative carbon budget in August and 0 in September, whereas it was positive the rest of the year. Photosynthetic efficiency, estimated by the ratio between maximum apparent photosynthesis and light half saturation constant, showed a strong agreement with productivity measured by means of an independent method. These results indicate that lamina expansion in this species is controlled by photosynthetic efficiency .