Charlotta Nygård

Cadmium tolerance and adsorption by the marine brown alga Fucus vesiculosus from the Irish Sea and the Bothnian Sea

Cadmium (Cd) uptake capacities and Cd tolerance of the marine alga Fucus vesiculosus from the Irish Sea (salinity 35 psu) and from the Bothnian Sea (northern Baltic, 5 psu) were quantified. These data were complemented by measurements of changes in maximal photosynthetic rate (P(max)), dark respiration rate and variable fluorescence vs. maximal fluorescence (F(v):F(m)). At concentrations between 0.01 and 1 mmol Cd l(-1), F. vesiculosus from the Bothnian Sea adsorbed significantly more (about 98%) Cd compared with F. vesiculosus from the Irish Sea. The photosynthetic measurements showed that the Bothnian Sea F. vesiculosus were more sensitive to Cd exposure than the Irish Sea algae. The algae from the Irish Sea showed negative photosynthetic effects only at 1 mmol Cd l(-1), which was expressed as a decreased P(max) (-12.3%) and F(v):F(m) (-4.6%). On the contrary, the algae from the Bothnian Sea were negatively affected already at Cd concentrations as low at 0.1 mmol Cd l(-1). They exhibited increased dark respiration (+11.1%) and decreased F(v):F(m) (-13.9%). The results show that F. vesiculosus from the Bothnian Sea may be an efficient sorption substrate for Cd removal from Cd contaminated seawater and this algae type may also have applications for wastewater treatment.

Photosynthesis and UV-B Tolerance of the Marine Alga Fucus vesiculosus at Different Sea Water Salinities

The marine algal species in the Baltic Sea are few due to the low sea water salinity. One of the few species that can be found is Fucus vesiculosus. Even this species is affected by the low salinity and becomes smaller in size in the Baltic. In present work the photosynthesis of F. vesiculosus in the northern Baltic (Bothnian Sea) was compared to the photosynthesis of F. vesiculosus in the Atlantic. Oxygen evolution was measured before and after exposure to 2.3 W of UV-B (280–320 nm) radiation for 5 h, as well as after 48 h recovery in low light. The plants were kept in their own sea water salinity as well as in a changed salinity, this to examine possible correlations between salinity and photosynthesis. The results show a significant higher initial maximal photosynthesis (Pmax) for Atlantic plants (10.3 nmol O2 g−1 FW s−1) compared to Baltic plants (4.0 nmol O2 g−1 FW s−1). The Baltic plants were found more sensitive to UV-B with a 40–50% decrease of Pmax as well as a lower degree of recovery (60–70% compared to 75–95% for the Atlantic plants). The higher salinity (35 psu) had a positive effect on the Baltic F. vesiculosus with increased Pmax as well as increased tolerance to UV-B. The lower salinity (5 psu) had a negative effect on the Atlantic plants with a decreased Pmax as well as a lower tolerance to UV-B. Pigment content was found higher in Atlantic F. vesiculosus. The pigment content decreased then the Atlantic plants were transferred to 5 psu. The concentration of Chl a as well as the total content of violaxanthin, diadinoxanthin and zeaxanthin in Baltic plants increased when transferred to 35 psu. The Atlantic F. vesiculosus can not survive the low salinity in the northern Baltic (died within 8 weeks). It is likely that a long time acclimation or adaptation to low salinity has taken place for F. vesiculosus in northern Baltic. If this is an ecotypic or genotypic development it is too early to say.

Desiccation and salinity effects on marine and brackhish Fucus vesiculosus L. (Phaeophyceae).

A.M. Gylle, C.A. Nygård and N.G.A. Ekelund. 2009. Desiccation and salinity effects on marine and brackish Fucus vesiculosus L. (Phaeophyceae). Phycologia 48: 156–164. DOI: 10.2216/08-45.1. 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.

Effects of lead (PaCl2) on photosynthesis and respiration of the bladder wrack, Fucus vesiculosus, in relation to different salinities

The photosynthetic and respiratoric capacity of Fucus vesiculosus grown at three different levels of salinity (4.5, 8 and 20‰) was studied in the presence of different concentrations of lead (5, 10, 15, 20, 25, and 30 mg PbCl2 L−1). The studies were performed by using a light-pipette, which has a precisely defined light source of photosynthetic active radiation (PAR, 400–700 nm). The photosynthetic and respiratoric capacity of the algae were measured when exposed to light pulses with increasing irradiance and after 24 hr in seawater with the addition of lead. The results indicate that the photosynthetic capacity of F. visiculosus from 20‰ is more sensitive to lead compared to those from 8 and 4.5‰. The photosynthetic capacity was reduced by 69% at 30 mg PbCl2 L−1 compared to the control alga. The photosynthetic capacity of F. vesiculosus from 8 and 4.5‰ was reduced by 38 and 15%. The respiratoric capacity of F. vesiculosus from 20‰ was reduced by 41% at 30 mg PbCl2 L−1. However, the respiratoric capacity of the algae from 4.5‰ increased by 55% at the same concentration of PbCl2. The results indicate that lead showed inhibitory effects on photosynthesis but a stimulatory effect on respiration of F. versiculosus grown at low levels of salinity.

Photosynthesis in relation to D1, PsaA and Rubisco in marine and brackish water ecotypes of Fucus vesiculosus and Fucus radicans (Phaeophyceae)

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 (Pmax) in the Atlantic Ocean ecotype of F. vesiculosus relative to the Baltic Sea ecotype, and an increase of the Pmax 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 Pmax between the two ecotypes of F. vesiculosus might be related to the difficulties for the algae to adapt to the environment in Bothnian Sea.

Impacts of UV-radiation on photosynthesis of Fucus vesiculosus at low temperature and different salinities

Impacts of UV-radiation on photosynthesis of Fucus vesiculosus at low temperature and different salinities