Physiology of Laminaria

Abstract. Dissolved nitrate, nitrite, ammonium and phosphate were monitored for 2.5 years along a coastal eutrophication gradient originating at the St. Andrews sewer outfall. Linear growth rates and tissue composition (phosphorus, various nitrogen fractions and storage carbohydrates) were monitored at the same stations in lamina tissue of Laminaria digitata and L. saccharina. Growth rates were considerably enhanced at the eutrophicated stations both in spring, when exogenous nutrients were at peak values at all stations, and during the summer when exogenous nutrients were very low at all stations. Enhanced summer growth rates were correlated with the increased reserves of N and P accumulated during winter and spring, and particularly with soluble organic nitrogen reserves. Accumulation of storage carbohydrates was inversely correlated with growth rate and tissue N and P reserves, presumably because fixed carbon could be incorporated into new protein and thence new tissue only if internal non-protein N reserves were available.     

Physiology of Laminaria

Abstract. Discs of lamina tissue excised from Laminaria digitata, L. hyperborea and L. saccharina were unaffected by cutting. They photosynthesized at a constant rate for several days and increased in area and weight during prolonged bubble cultures at a rate comparable with that of plants on the shore.     

Effects of Dredging Activities on Growth of Laminaria saccharina

Abstract. The possible effects of fine-grained deposits on the photosynthesis, growth, and nutrient uptake of Laminaria have been studied in field and laboratory experiments. Some of the plants were treated with fine-grained material for two hours and then transplanted in rows together with untreated plants. At two-week intervals the treatment was repeated and samples collected. The macroalgae were analyzed for growth as well as chlorophyll a , nitrogen, and phosphorus content. In the laboratory experiments, plants of a uniform size were incubated in Plexiglas containers after leaf-marking and treatment in a sediment suspension. At weekly intervals, photosynthesis, growth, chlorophyll a , and nutrients were analyzed.
The field study showed that Laminaria growth was significantly affected by the fine-grained material. The growth in the control experiment was 20% higher than in the treated plants. The chlorophyll a concentrations in the treated plants were significantly lower than in the control experiment, and the results indicated a reduced nutrient uptake in the treated plants. In the laboratory experiments the growth of the treated plants was only 30% of the controls, but no differences in photosynthetic capacities were detected. Nitrogen uptake was reduced in the treated plants, but no effects were observed on phosphorus uptake. Thick layers of fine-grained material caused direct harmful effects and rotting.
The results are discussed in relation to dredging activities; it is concluded that in heavy sedimentation areas, Laminaria growth may be significantly reduced beyond the indirect effect of shading from suspended material in the water.     

海带属褐藻生物学研究成就与进展

以海带(Laminaria ja ponica Aresch)为重点，综述了海带属褐藻生物学研究成就，介绍了海带属褐藻遗传育种技术、育苗技术和分子生物学研究进展。海带属褐藻生物学研究基础好，种质资源丰富，经济、生态价值高，是进行大型海藻遗传学和基因组学研究的理想材料。     

The Effects of Zn, Mn, and Co Accumulation on Growth and Chemical Composition of Fucus vesiculosus L under Different Temperature and Salinity Conditions

Abstract. Combined effects of temperature, salinity, and metal enrichment (Zn, Mn, Co) on the growth rate and chemical composition of Fucus vesiculosus L. were studied in culture. Factorial combinations of two temperatures and three salinities were used. The results indicated that the accumulation of Zn and Mn into algal tissue was enhanced by dilution of the media, whereas Co accumulation exhibited maxima at the medium salinity. Zn accumulation was enhanced by temperature, while the opposite was true for Mn and Co.
In the presence of metals the usual dilution-induced changes in growth activity and chemical composition of Fucus plants were altered, while responses to the temperature factor remained unchanged. In diluted media, growth activity and mannitol content decreased along with a simultaneous increase of protein content. In the presence of Zn and Mn the mannitol content exhibited peaks at the medium salinity; in the presence of Co the dilution-induced pattern remained unchanged. Salinity-induced changes in growth and protein content were altered in the presence of metals. Maxima in growth rates were found at the medium salinity. Growth was higher in extremely diluted media than in scawater, indicating an inversion of responses to the salinity factor. Both the growth rate and mannitol content were lowest under the influence of Zn.     

Effect of emersion and immersion on the porewater nutrient dynamics of an intertidal sandflat in Tokyo Bay

Porewater nutrient dynamics during emersion and immersion were investigated during different seasons in a eutrophic intertidal sandflat of Tokyo Bay, Japan, to elucidate the role of emersion and immersion in solute transport and microbial processes. The water content in the surface sediment did not change significantly following emersion, suggesting that advective solute transport caused by water table fluctuation was negligible. The rate of change in nitrate concentration in the top 10 mm of sediments ranged from −6.6 to 4.8 μmol N l⁻¹ bulk sed. h⁻¹ during the whole period of emersion. Steep nutrient concentration gradients in the surface sediment generated diffusive flux of nutrients directed downwards into deeper sediments, which greatly contributed to the observed rates of change in porewater nutrient concentration for several cases. Microbial nitrate reduction within the subsurface sediment appeared to be strongly supported by the downward diffusive flux of nitrate from the surface sediment. The stimulation of estimated nitrate production rate in the subsurface layer in proportion to the emersion time indicates that oxygenation due to emersion caused changes in the sediment redox environment and affected the nitrification and/or nitrate reduction rates. The nitrate and soluble reactive phosphorus pools in the top 10 mm of sediment decreased markedly during immersion (up to 68% for nitrate and up to 44% for soluble reactive phosphorus), however, this result could not be solely explained by molecular diffusion.     

组织培养获得的海黍子幼孢子体的营养盐吸收和生长特性的研究

以组织培养间接获得的海黍子幼孢子体为实验对象,研究温度和氮、磷浓度对其营养盐吸收和生长的影响。结果显示,15~30℃范围内幼孢子体均可吸收NO-3-N、NH+4-N和PO3-4-P。25~30℃下NH+4-N的吸收显著高于10~15℃时,而NO-3-N和PO3-4-P的吸收速率在实验温度下差异不显著。NO-3-N、NH+4-N和PO3-4-P的最大吸收速率分别出现在15、25和25℃。当氮浓度3 000μg·L-1时,幼孢子体均可吸收NO-3-N和NH+4-N,且二者均呈现开放型吸收模式。当磷浓度30μg·L-1时,幼孢子体可吸收PO3-4-P,且呈现饱和型模式。温度对幼孢子体的生长影响显著。10~30℃范围内,富含氮磷组和去除氮磷组的特定生长率(SGR)均随着温度的升高先增大后减小,且最大SGR(分别为19.58%·d-1和14.58%·d-1)均在25℃时取得;叶绿素a、c的含量随着温度的升高先减小后增大。氮、磷浓度对幼孢子体的生长影响显著。富含氮磷组的SGR、叶绿素a含量和叶绿素c含量分别在15~25℃、15~30℃和20~30℃范围内显著高于去除氮磷组。