Seasonal Changes of Nitrogen Metabolism in the Sporophyte of Laminaria japonica (Phaeophyceae).

Abstract

The seasonal changes of nitrogen metabolism in the sporophyte of Laminaria japonica (Phaeophyceae) were investigated under a natural environment. The experiment was conventionally distinguished by concentrations of nitrogen compounds dissolved in seawater, that is, a relatively high NO2-+NO3-concentration period and a low one. In the high-nitrogen period, the prominent nitrogen metabolism was nitrogen uptake, assimilation, and accumulation. After the ambient nitrite+nitrate was exhausted from the seawater, the nitrogen metabolism was displaced to the utilization of the stored nitrogen. When the nitrogen limitation in the blade was severe about two months after entering the low-nitrogen period, the metabolism was characterized by the utilization of catabolite NH4+ in apical blade tissues. It was suggested from these results that the nitrogen metabolism was divided into three periods: (i) nitrogen uptake and assimilation, (ii) the utilization of stored nitrogen, and (iii) catabolic and re-assimilation periods, with the change in the nitrogen environment. Furthermore, the critical nitrogen content for maintaining maximum growth and the subsistent nitrogen content were 2.4 and 1.3% (on a dry weight basis), respectively. It is suggested that these nitrogen contents are useful for predicting the nitrogen status of the blade and for the effective management of L. japonica cultivation.

Seasonal Variations in Surface Metabolite Composition of Fucus vesiculosus and Fucus serratus from the Baltic Sea

“…The lack of a significant relationship between nutrient availability and surface metabolite composition in the present study may be attributable to the fact that many macroalgae, including F . vesiculosus , have the ability to use internal nitrogen reserves for metabolic performances such as growth during seasons of nitrogen deficiency [72–74]. Therefore, it seems reasonable that the metabolism of both Fucus species was probably not nitrogen or nutrient-limited during our survey (August 2012—July 2013).…”

Productivity and thallus toughness trade‐off relationship in marine macroalgae from the Japan Sea

“…c) for the maintenance of a positive carbon balance in photosynthesis of warm temperate macroalgae tends to be slightly higher than that (1.6%) reported in the cold temperate kelps (Sakanishi et al ). This value was higher than the sustenance nitrogen contents (contents required for the growth rate equal to zero) reported in kelps (1.3%) and other marine macroalgae (0.4–1.2%) (Chapman et al ; Mizuta et al ; Pedersen & Borum ). The positive x‐intercept of the regression line (A mass = 14.4 N mass – 26.9) indicates that the photosynthetic capacity per unit nitrogen (= PNUE) decreases with decreasing N mass (Field & Mooney ; Sakanishi et al ).…”

“…The relationship between growth or photosynthesis and nitrogen content has been widely determined in various plants (Field & Mooney 1986;Evans 1989;Björnsäter & Wheeler 1990;Poorter et al 1990;Mizuta et al 1992;Pedersen & Borum 1997). A critical nitrogen content of 1.9% (x-intercept of the regression line in Fig.…”

Differences in resource storage pattern between Laminaria longissima and Laminaria diabolica (Laminariaceae; Phaeophyta) reflecting their morphological characteristics

“…The two species each retained their specific storage pattern in Matsushima Bay, indicating that storage patterns are likely to be determined by genetic characteristics. Mizuta et al (1992) and Li et al (2007) reported that carbon and nitrogen were transferred and stored intensively in the meristem in L. japonica. The results of the present study demonstrate that L. diabolica uses the same storage pattern as L. japonica, while L. longissima has a different pattern even though the two species grow under similar conditions determined by the Oyashio Current.…”

“…Mizuta et al (1992) and Li et al (2007) reported that carbon and nitrogen produced through photosynthesis and nutrient uptake and recycled through erosion of apical tissues were transferred and stored intensively in the meristem of L. japonica. However, Mizuta et al (1992) have argued that erosion of the apical tissues is triggered by ambient nutrient levels and internal storage of resources contents, while Li et al (2007) later proved that this strategy is based on a genetic characteristic. The questions: "does L. diabolica have the same storage pattern as that of L. japonica, with L. longissima having a different pattern?"…”