Effect of pH and salinity on the removal of phytal animals during summer cultivation of Sargassum fusiforme and Sargassum fulvellum in Korea

Abstract

The brown seaweeds, Sargassum fusiforme and Sargassum fulvellum are edible and highly valued in Korea. During the summer season, phytal animals graze heavily on young algal blades and holdfasts of these two species and substantially reduce harvestable biomass. Acid and salinity treatments are used to efficiently control infestations by phytal animals in other cultivated algae (e.g., Pyropia), but their effects on the removal of phytal animals in Sargassum cultivation are unknown. Here we investigated the effects of pH (range 2~13) and salinity (range 0~44 psu) on the removal of two major phytal animals, Caprella scaura and Gammaropsis utinomi, associated with S. fusiforme and S. fulvellum. We also examined the optimum quantum yield (F v /F m ) of algae in the same experimental conditions to quantify the tolerance of algae to acid and salinity treatments. The two animal species experienced more than 80 % mortality at pH lower that pH 4 and the extreams of salinity (0~10 and 44 psu) after a 5-min of immersion. The quantum yield of S. fulvellum was not significantly different from controls (ambient pH and salinity) within the pH 4-10 range and within the 7-40 psu salinity range. Similarly, the quantum yield of S. fusiforme was not significantly different from controls within the pH 3-11 range and the 0-44 psu salinity range. Therefore, if pH and salinity conditions outside these ranges were used in commercial Sargassum culture, the removal of the two animal species would be higher, but quantum yield of algae would be substantially reduced. These results indicate that pH and salinity treatments could be used effectively to remove the phytal organisms without significantly affecting optimum quantum yield in S. fusiforme and S. fulvellum.

Hidden diversity and phylogeographic history provide conservation insights for the edible seaweed Sargassum fusiforme in the Northwest Pacific

“…Sargassum fusiforme (Harvey) Setchell is a large brown alga found in the lower intertidal zone throughout southern Japan, the rim of the Yellow–Bohai Sea, and East China Sea (Figure ). Ecologically, this species can form dense beds and make substantial contribution to coastal marine ecosystems by acting as primary producer, providing spawning, nursery, and feeding grounds for fish and invertebrates, and improving environmental conditions (e.g., water motion and temperature) (Hwang, Yoo, Baek, & Park, ). Socioeconomically, S. fusiforme is widely utilized as food, polysaccharide resource, and medical agent (Mao, Li, Gu, Fang, & Xing, ; Zhu, Heo, & Row, ).…”

Effects of Temperature and pH on the Growth of Sargassum linearifolium and S. podacanthum in Potassium-Fortified Inland Saline Water

“…Temperature and pH strongly influence the growth of Sargassum (Choi et al, 2007;Chen and Zou, 2014;Hwang et al, 2015). The Sargassum growth rate is strongly affected by the variation of temperature (Uchida, 1993;Endo et al, 2013) and the effect of temperature within the tested range was stronger than the pH, shown by the significant different SGR of Sargassum at different temperature levels.…”

“…(Davis et al, 2000). In OW, the chlorophyll fluorescence of S. fusiforme and S. fulvellum varies little over in the pH of 4-10 (Hwang et al, 2015) and the suitable pH for S. honeri zygote germination is 5-10 (Ogawa, 1984). Similarly, the temperature is a vital factor affecting Sargassum growth (Uchida, 1993).…”

The effects of desiccation and salinity gradients on the PSII photochemical efficiency of an intertidal brown alga, Sargassum fusiforme from Kagoshima, Japan

“…The adaptation to the broad range of salinity observed in our study supports previous reports despite the different methods and duration of experiments (Hwang et al . 2015; Gao et al . 2016; Xie et al .…”

“…The responses of photosynthesis and growth, especially carbon acquisition and pigment composition, under desiccation and salinity stresses have been reported by some pioneering studies (Ji & Tanaka 2002; Zou & Gao 2004; Hwang et al . 2015; Xie et al . 2016; Gao et al .…”