Mid Sweden University

The aim of this study was to investigate photosynthetic differences between the marine, Norwegian Sea ecotype and the brackish, Bothnian Sea ecotype of F. vesiculosus and F. radicans and to see whether photosynthetic differences could be connected with the relative amounts of D1 protein (PSII), PsaA (PSI) protein and/or Rubisco. For this purpose, we tested if a higher photosynthetic maximum (P (max)) in the Atlantic Ocean ecotype of F. vesiculosus relative to the Baltic Sea ecotype, and an increase of the P (max) in Baltic Sea ecotype of F. vesiculosus at higher salinity, could be due to an increase in the relative amounts of Rubisco. The proteins have been evaluated on a relative basis. Immunoblot signals showed that the amount of Rubisco was higher in both ecotypes of F. vesiculosus than in F. radicans, but no differences could be detected between the two ecotypes of F. vesiculosus. The results suggest an uneven photosystem protein stoichiometry in Fucus, with more of the PSI protein PsaA relative to the PSII protein D1. The difference in P (max) between the two ecotypes of F. vesiculosus might be related to the difficulties for the algae to adapt to the environment in Bothnian Sea.

This study investigates the effects of different light qualities on the photosynthetic capacity of the brown algae Fucus vesiculosus, from the Norwegian Sea, and Fucus radicans and F. vesiculosus, from the Bothnian Sea. The electron transport rates (ETR) obtained for F. vesiculosus from the Norwegian Sea showed significantly higher levels of light saturation compared with both species of algae from the Bothnian Sea. The maximum of ETR values for the Norwegian Sea strain showed no significant changes due to varying light quality compared with the initial values. For F. vesiculosus, from the Bothnian Sea, treatment with blue light showed an effect after 1 week of 30 and 90 μmol photons m -2 s -1 (P < 0.01), and for F. radicans from the Bothnian Sea, at the irradiance of 90 μmol photons m -2 s -1 and 1 week (P < 0.01). After 1 week in the Bothnian Sea species and after 2 weeks in F. vesiculosus from the Norwegian Sea, the photosynthetic efficiency (α) was significantly higher regardless of light quality and irradiance compared with the initial values. Variation in light quality and irradiance had minor effects on the F v:F m values of the three algal strains studied. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

The Bothnian Sea in the northerly part of the Baltic Sea is a geologically recent brackish-water environment, and rapid speciation is occurring in the algal community of the Bothnian Sea. We measured low-temperature fluorescence emission spectra from the Bothnian Sea and the Norwegian Sea ecotypes of Fucus vesiculosus L., a marine macroalga widespread in the Bothnian Sea. Powdered, frozen thallus was used to obtain undistorted emission spectra. The spectra were compared with spectra measured from the newly identified species Fucus radicans L.Bergström et L. Kautsky, which is a close relative of F. vesiculosusand endemic to the Bothnian Sea. The spectrum of variable fluorescence was used to identify fluorescence peaks originating in PSI and PSII in this chl c–containing alga. The spectra revealed much higher PSII emission, compared to PSI emission, in the Bothnian Sea ecotype of F. vesiculosus than in F. radicans or in the Norwegian Sea ecotype of F. vesiculosus. The results suggest that more lightharvesting chl a ⁄ c proteins serve PSII in the Bothnian Sea ecotype of F. vesiculosusthan in the two other algal strains. Treatment of the Bothnian Sea ecotype of F. vesiculosusin high salinity (10, 20, and 35 practical salinity units) for 1 week did not lead to spectral changes, indicating that the measured features of the Bothnian Sea F. vesiculosus are stable and not simply a direct result of exposure to low salinity.

Ecotypes of Fucus vesiculosus L. from the Norwegian Sea (34 psu, marine ecotype) and Bothnian Sea (5 psu, brackish ecotype) have been compared with respect to the ability to withstand desiccation at different temperatures (0, 10, and 20°C). The aim was also to investigate the importance of salinity and light for the availably energy reserves, osmotic adjustment, and pigment content. The maximum quantum yield of photosystem II photochemistry (Fv/Fm) values revealed that the marine ecotype was more able to resist desiccation. The brackish algae showed a decrease in Fv/Fm as a response to desiccation at all temperatures, but the decrease was most pronounced at 20°C. The brackish ecotype recovered from desiccation within 5 h only when treated at 0°C. When the two ecotypes were treated at different levels of salinity in darkness and light, the results suggested that both salinity and irradiance are main factors in the differences in mannitol content between the two ecotypes. Chlorophyll (Chl) measurements showed 25% higher Chl α and 60% higher Chl c in the brackish ecotype in comparison to the marine ecotype. Darkness had a more pronounced effect on the Chl content than the salinity and initiated an increase in the amount of Chl, especially Chl c in the brackish ecotype.

In the present study we compared the contents of water soluble organic compounds of the marine intertidal ecotype of Fucus vesiculosus (Phaeophyceae) from the Norwegian Sea (34 practical salinity units, psu) with the sublittoral ecotype of F. vesiculosus from the brackish Bothnian Sea (5 psu). Nuclear magnetic resonance spectra revealed that marine F. vesiculosus had additional types of water soluble organic compounds compared with brackish F. vesiculosus. The results suggested that glycine betaine in the marine ecotype could be the reason for this ecotype differentiation. Furthermore, the qualitative differences between the ecotypes were the same after one week's treatment of marine algae in brackish water and of brackish algae in marine water. These suggest that the additional types of water soluble organic compounds in marine F. vesiculosus are not caused by the salinity conditions at the growth sites. Further research concerning other environmental factors that may influence ecotype differentiation of water soluble organic compounds qualitative content and adaptation in F. vesiculosus is recommended.

The brown alga Fucus vesiculous is one of the few marine species in the Baltic Sea. F. vesiculosus shows high morphological and physiological variability as a response to its environmental conditions. The salinity in the Baltic Sea is 4-5 psu in comparison to 35 psu in the Atlantic. Photosynthesis of algae is usually measured after collection and transportation to constant culture conditions. However, in this study the relative photosynthetic electron transport rate (rETR), calculated from chl a fluorescence parameters were compared for algae from 1 and 4 m depths by SCUBA divers. Measurements of light response curves from the same individuals of F. vesiculosus at different depths and times of the year have to our knowledge never been made before. Measurements were performed at four different occasions during the spring (February 25, April 3 and 29 and May 26 in 2005) in the Baltic Sea, using rapid light curves (RLCs) generated with a Diving PAM. In addition, samples were collected for photoinhibition studies in the laboratory. The light response curves obtained in situ at 1 and 4 m depths for F. vesiculosus showed lower values of light saturation with depth. When algae from 1 and 4 m depths were exposed to high irradiances of PAR (1400 µmol photons m-2 s-1), algae from 1 m depth showed a higher degree of photoinhibition in comparison to algae from the 4 m depth.