Öz Intertidal seaweeds exposed to strong fluctuation in light quantity and spectral light quality. Light plays an important role controlling seaweed growth and physiology. Therefore, we conducted a culture experiment to determine the physiological effects of light intensity on the opportunistic algae Ulva rigida C. Agardh. For this reason, samples were exposed to two different light intensities (55 µmol photons m-2s-1 and 100 µmol photons m-2s-1) and their some physiological features including photosynthetic performance, growth rate, pigment content, total protein and nitrate reductase activity were measured. According to our results, the maximum relative electron transport rate and saturation irradiance point were not significantly different between the treatments. On the other hand, relative growth rate, nitrate reductase activity and chlorophyll-a concentrations of U. rigida were significantly decreased under low light condition. Consequently, our data indicated that photosynthetic perfomance of Ulva rigida was not affected to treated light intensity, while growth and nitrogen metabolism were primarily controlled by light.
1. Smetacek, V.; Zingone, A. Green and golden seaweed tides on the rise. Nature, 2013; 504, 84-88.
2. Cohen, I,; Neori, A. Ulva lactuca Biofilters for Marine Fish-pond Effluents. Botanica Marina, 1991; 34, 475-482.
3. Rinehard, S.; Guidone, M.; Ziegler, A.; Schollmeier T.; Thorn-ber, C.S. Overwintering strategies of bloom-forming Ulva species in Narragansett Bay, Rhode Island, USA. Botanica Marina, 2014; 57(4), 337-341.
4. Thomsen, M.; McGlathery K. Effects of accumulations of sediments and drift algae on recruitment of sessile organisms associ-ated with oyster reefs. Journal of Experimental Marine Biology and Ecology, 2006; 328, 22-34.
5. Deacutis, C. Evidence of Ecological Impacts from Excess Nutrients in upper Naragansett Bay. Science for Ecosystem Based Management; Desbonnet, A., Costa-Pierce, B.A., Eds.; Springer: New York, 2008; 349-381.
6. Hader, D.P.; Figueroa, F.L. Photoecophysiology of Marine Macroalgae. Journal of Photochemistry and Photobiology B: Biol-ogy, 1997; 66, 1-14.
7. Mercado J.M.; Gordillo, F.J.L.; Figueroa, F.L.; Niell, F.X. External carbonic anhydrase and affinity for inorganic carbon in intertidal macroalgae. Journal of Experimental Marine Biology and Ecology, 1998; 221, 209-220.
8. Provasoli, L. Media and Prospects for the Cultivation of Marine Algae: Cultures and Collections of Algae. Proceedings of the US-Japan Conference, Hakone, September 1966; JPN. Soc. Plant Phys-iol. 1968; 63-75.
9. Bischof, K.; Hanelt, D.; Wiencke, C. Acclimation of Maximal Quantum Yield of Photosynthesis in the Brown Alga Alaria esculenta under High Light and UV Radiation. Plant Biology, 1999; 1, 435-444.
10. Eilers, P.H.C.; Peeters, J.C.H. A Model for the Relationship Between Light Intensity and the Rate of Photosynthesis in Phyto-plankton. Ecological Modelling, 1988; 42, 199-215.
11. Inskeep, W.P.; Bloom, P.R. Extinction Coefficients of Chloro-phyll a and b in N,N-dimethylformamide and 80% Acetone, Plant Physiology, 1985; 77, 483-485.
12. Bradford, M. A Rapid and Sensitive Method for the Quantiza-tion of Microgram Quantities of Protein Utilizing the Principle of Protein-Dye Binding. Analytical Biochemistry, 1976; 72, 248-254.
13. Corzo, A.; Niell, F.X. Determination of Nitrate Reductase Activi-ty in Ulva rigida C. Agardh by the in situ Method, Journal of Expe-rimental Marine Biology and Ecology, 1991; 146, 181-191.
14. [Snell, F.D.; Snell, C.T. Colorimetric Methods of Analysis, Vol. 2, 3rd edn. Princeton, NJ:Van Nostrand, 1949.
15. Maxwell, K.; Johnson, G.N. Chlorophyll Fluorescence- a prac-tical Guide. Journal of Experimental Botany, 2000; 51, 659-668.
16. Krause, G.H.; Weis, E. Chlorophyll Fluorescence and Photosyn-thesis: the Basics. Annual Review of Plant Physiology and Plant Molecular Biology, 1991; 42, 313-349.
17. Rautenberger, R.; Fernandez, P.A.; Strittmatter, M.; Heesch, S.; Cornwall, C.E.; Hurd, C.L.; Roleda, M.Y. Saturating Light and not Increased Carbon Dioxide under Ocean Acidification Drives Photo-synthesis and Growth in Ulva rigida (Chlorophyta). Ecology and Evolution, 2015; 5(4), 874- 888.
18. Young, E.B.; Berges, J.A.; Dring, M.J. Physiological Responses of Intertidal Marine Brown Algae to Nitrogen Deprivation and Resupply of Nitrate and Ammonium. Physiologia Plantarum, 2009; 135, 400-411.
19. Chow, F.; Oliveira, M.C.; Pedersen M. In vitro assay and light regulation of nitrate reductase in red alga Gracilaria chilensis. Journal of Plant Physiology. 2004; 161, 769-776.
20. Young, E.B.; Dring, M.J.; Berges, J.A. Distinct pattern of nitrate reductase activity in Brown algae: Light and ammonium sensitivity in Laminaria digitata is absent in Fucus species. Journal of Phyco-logy, 2007; 43, 1200-1208.
21. Pritchard, D.W.; Hurd, C.L.; Beardall, J.; Hepburn, C.D. Rest-ricted use of nitrate and astrong preference for ammonium reflects the nitrogen ecophysiology of a light limited re dalga. Journal of Phycology, 2015; 51, 277-287.