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FLUORESCENCE INDUCTION AND PHOTOSYNTHETIC RESPONSES OF ARCTIC ICE ALGAE TO SAMPLE TREATMENT AND SALINITY 1
Author(s) -
Bates Stephen S.,
Cota Glenn F.
Publication year - 1986
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.1529-8817.1986.tb02484.x
Subject(s) - salinity , photosynthesis , algae , seawater , dcmu , biology , chlorophyll fluorescence , temperature salinity diagrams , botany , photosystem ii , oceanography , ecology , geology
The measurement of Photosynthetic rates of algae growing on the undersurface of 1. 7 m thick ice in the Canadian Arctic (Resolute Passage. N.W.T.) presents several problems. During the preparation of samples for physiological measurements, the ice algae may he exposed to salinity and temperature shocks. Fluorescence induction (the rise in in vivo Chl a fluorescence intensity during a period of millineconds) and photosynthesis‐irradiance (PI) experiments examined the potential effects of salinity and temperature on the physiology of ice algae . Experimental suspensions were routinely prepared by scraping one part ire crystals (11–14% 0 salinity) and attached algae from the bottom ice into four parts filtered seawater (32% 0 salinity). giving a final salinity of 28–31% 0 . Post‐dilution of melted ice scrapings with seawater suppressed photosynthetic 14 C‐fixation and decreased A DCMU (the area above the fluorescence induction curve measured in the presence of the inhibitor DCMC: an estimate of photosynthetic capacity) by a factor of 3–16. due to the low salinity of the melted ice scrapings. Fluorescence induction and PI experiments showed that the ice algae had a salinity optimum near 30% 0 , close to the ambient seawater salinity, Experiments in which the Chl a concentration was manipulated showed that A DCMU , P a m (Chl a‐normalized rate of photosynthesis at light saturation), and a (photosynthetic efficiency) declined with increasing Chl a concentration. Ice algae tolerated heating (l.5°C‐min ‐1 ) up to 17° C, above which A DCMU’ decreased with sample temperature .