Effects of temperature, light level, photoperiod, and ammonium concentration on Pyropia leucosticta (Bangiales, Rhodophyta) from the Northwest Atlantic

Abstract

Seaweed aquaculture in the Northwest Atlantic is a growing industry that is currently based on winter-spring kelp production. Aquaculture of Pyropia leucosticta, a species of economically valuable nori, could provide a spring-summer crop and diversify the industry. The objectives of this study were to determine the optimum conditions for the production of the foliose blade phase and the conditions for advancement from the microscopic conchocelis to the foliose blade phase of P. leucosticta. Foliose blades were grown under a matrix of temperatures (10, 15, and 20°C), photoperiods (8:16, 12:12, and 16:8 L:D), and light levels (30, 60, 110, and 250 μmol photons m −2 s −1 ) for a period of 1 month. Free-living conchocelis was grown under a matrix of temperatures (10, 15, and 20°C), photoperiods (8:16, 12:12, and 16:8 L:D), and ammonium concentrations (20 and 500 μM) for 8-12 weeks. Blades grew optimally at 10 to 15°C, ≥110 μmol photons m −2 s −1 and ≥12 h of light in the day, with growth rates of over 18 % day −1 recorded. Phycobilin content of blades significantly decreased with increasing day length, while protein content significantly decreased with increasing light level. Conchospore release and germination was observed after approximately 40 days under all tested photoperiods, temperatures, and ammonium concentrations and none of these treatments significantly affected the time until germination. Overall, this study provides important background information required for the establishment of Pyropia leucosticta aquaculture in the Northwest Atlantic.

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

“…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

“…Pyropia species originating from warm waters endure and adapt to higher temperatures than those from cold waters (Sahoo et al 2006;Kim 2011). Different geographic strains of Pyropia species adapt to different environmental conditions (Dring 1967;Yarish 2006: Watanabe et al 2014;Green and Neefus 2015).There was a 5°C-interval in the experimental design (Notoya et al 1993;Kim 1999). Here, we used lower temperature intervals (25, 28, and 31°C) to look for more differences during P. dentata conchocelis developing into conchosporangia.…”

“…Different life stages can be manipulated both in the laboratory and on an industrial scale. Light, temperature, and photoperiod play a major role during each life stage of Pyropia (Notoya et al 1993;Sahoo et al 2006;Green and Neefus 2015). Three distinct stages are present during conchocelis development: vegetative growth, conchosporangia formation, and conchospore release, which are all affected by environmental factors (Nelson et al 1999;Wang et al 2008).…”

“…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).…”

“…The seeding industry has failed to obtain high proportions of conchosporangia and massive synchronous release of conchospores by adopting the parameters applied in P. yezoensis and P. haitanensis seeding. Given that different geographical strains of the same species adapt to different environmental conditions (Dring 1967;He and Yarish 2006;Watanabe et al 2014;Green and Neefus 2015), the light and temperature factors necessary to obtain optimal conchocelis development of P. dentata from Guangdong, China may be different from those needed for P. dentata from Korea and Japan (Notoya et al 1993;Kim 1999).…”