Effect of irradiance and temperature on the photosynthesis of a cultivated red alga, Pyropia tenera (= Porphyra tenera), at the southern limit of distribution in Japan

Abstract

Summary The effect of irradiance and temperature on the photosynthesis of the red alga, Pyropia tenera, was determined for maricultured gametophytes and sporophytes collected from a region that is known as one of the southern limits of its distribution in Japan. Macroscopic gametophytes were examined using both pulse‐amplitude modulated fluorometry and/or dissolved oxygen sensors. A model of the net photosynthesis–irradiance (P‐E) relationship of the gametophytes at 12°C revealed that the net photosynthetic rate quickly increased at irradiances below the estimated saturation irradiance of 46 μmol photons m−2 s−1, and the compensation irradiance was 9 μmol photons m−2 s−1. Gross photosynthesis and dark respiration for the gametophytes were also determined over a range of temperatures (8–34°C), revealing that the gross photosynthetic rates of 46.3 μmol O2 mgchl‐a−1 min−1 was highest at 9.3 (95% Bayesian credible interval (BCI): 2.3–14.5)°C, and the dark respiration rate increased at a rate of 0.93 μmol O2 mgchl‐a−1 min−1°C−1. The measured dark respiration rates ranged from −0.06 μmol O2 mgchl‐a−1 min−1 at 6°C to −25.2 μmol O2 mgchl‐a−1 min−1 at 34°C. The highest value of the maximum quantum yield (Fv/Fm) for the gametophytes occurred at 22.4 (BCI: 21.5–23.3) °C and was 0.48 (BCI: 0.475–0.486), although those of the sporophyte occurred at 12.9 (BCI: 7.4–15.1) °C and was 0.52 (BCI: 0.506–0.544). This species may be considered well‐adapted to the current range of seawater temperatures in this region. However, since the gametophytes have such a low temperature requirement, they are most likely close to their tolerable temperatures in the natural environment.

Effect of abiotic stress on the gameophyte of Pyropia katadae var. hemiphylla (Bangiales, Rhodophyta)

“…hemiphylla, although F v /F m values decreased with longer period of culture, those at 5-15°C were similar at the same other conditions (Jiang et al 2013b). Similarly, F v /F m values of P. tenera declined significantly until the temperature was over 20°C (Watanabe et al 2014). Comparably, P n is more sensitive to temperature than F v /F m (Fig.…”

“…Previous study on P. tenera has shown that dark respiration increased almost linearly while the gross photosynthesis decreased with temperature increasing from 6 to 34°C (Watanabe et al 2014). Whatever the reason, a decline of P n in P. katadae var.…”

“…They are widespread in subtropic, warm, and cold seawaters. Different species and populations adapt to different temperatures, which is closely correlated with their geographic distribution (Watanabe et al 2014). P. katadae var.…”

“…Long and intensive selective breeding of cultivated Pyropia leads to reduced genetic diversity of the stock. It is necessary to recruit completely new Pyropia species and geographically distinct wild strains of cultivated species to diversify the genetic resources, to strengthen the tolerance to climate changes and disease, and to improve the product quality (Niwa et al 2009;Green and Neefus 2014;Watanabe et al 2014).…”

Developmental and physiological properties of Pyropia dentata (Bangiales, Rhodophyta) conchocelis in culture

“…Long and intensive selective breeding of cultivated Pyropia leads to a reduction in genetic diversity of the stock, increased fragility to adversity, and decline in product quality. Therefore, it is crucial to recruit entirely new Pyropia species (Niwa et al 2009;Watanabe et al 2014;Green and Neefus 2015;Wang et al 2016). P. dentata has been cultivated on an experimental scale in Shantou, Guangdong province over the past few years (Xu et al 2013;Chen et al 2015).…”