Yoichi Sato, Takayuki Fujiwara, Hikaru Endo . Density regulation of aquaculture production and its effects on commercial profit and quality as food in the cosmopolitan edible seaweed Undaria p2023 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Frontiers Media SA Aquaculture of marine macroalgae (i.e. seaweeds) such as the kelp Undaria pinnatifida is expected to contribute to future food and biomass production. Although macroalgal survival, biomass, and morphology are strongly affected by the density of individual plants in natural environments, little is known about the cultivation density (individuals per 1 m of cultivation rope) of macroalgae required to optimize aquaculture production, commercial profit (sales – labor expenses for processing), and quality as food. The present study examined the effect of increasing the cultivation density of U. pinnatifida from 10 to 200 individuals m<sup>-1</sup> on survival rate, biomass production, profit, and morphological features related to quality as food. Survival rate was almost 100% in all treatments, indicating self-thinning did not occur. Biomass production increased with increasing density, suggesting that the maximum density possible is in excess of 200 individuals m<sup>-1</sup>. However, although profit rose with increasing density from 10 to 120 individuals m<sup>-1</sup>, it did not rise further if density was further increased. Moreover, some morphological features related to quality increased or decreased with increasing density. On balance, these results suggest that 80-120 individuals m<sup>-1</sup> is an appropriate density range to optimize production of this species in terms of both profit and quality as food. However, only 10-30 individuals m<sup>-1</sup> was the density best suited to enhance production of the sporophyll form, which is known to be a nutritious food both for humans and sea urchins. DOI： 10.3389/fmars.2023.1085054
Hikaru Endo, Xu Gao . A New Classification Tool and a Systematic Review of Macroalgal Studies Disentangle the Complex Interactive Effects of Warming and Nutrient Enrichment on Primary P2022 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： FRONTIERS MEDIA SA In order to understand how global warming effects on ecosystem primary production may change depending on nutrient enrichment, a new classification is proposed to disentangle and recognize the combination of interactions among several factors, based on the effect direction (positive, negative, or neutral) and its changes induced in it by the other factor (synergizing, antagonizing, inducing no change, or changing it in some other way). Marine macroalgae were chosen (as primary producers for which there is the most experimental information available) to review the relevant studies on which this new classification can be tested. It was observed the positive effects of elevated temperature and nutrient enrichment often synergized each other within the temperature range between relatively low and optimal growth levels. However, the negative effect of further temperature elevation from optimal to higher levels was antagonized by nutrient enrichment in some studies but was synergized in others, depending on the range of temperature elevation. The positive effect of nutrient enrichment was antagonized (but still positive) by temperature increase above the optimum in many cases, although the effect sometimes switched to a negative effect depending on the magnitude of nutrient enrichment. These results predict that global warming will enhance bottom-up effects on primary production in cold seasons and areas, and there will be a negative warming effect on production in hot seasons and areas, but it may be possible to mitigate this effect by appropriate levels of nutrient enrichment. DOI： 10.3389/fmars.2022.774801 Web of Science
Yoichi Sato, Gregory N. Nishihara, Atsuko Tanaka, Dominic F. C. Belleza, Azusa Kawate, Yukio Inoue, Kenjiro Hinode, Yuhei Matsuda, Shinichiro Tanimae, Kandai Tozaki, Ryuta Terada, Hikaru Endo2021 · 記述言語： 英語 掲載種別： 研究論文（学術雑誌） 出版者・発行元： Frontiers Media SA The important role of vegetated ecosystems in the sequestration of carbon has gained strong interest across a wide variety of disciplines. With evidence growing of the potential for macroalgae ecosystems to capture carbon, there is burgeoning interest in applying newfound knowledge of carbon capture rates to better understand the potential for carbon sequestration. Seaweed farms are expected to play a significant role in carbon capture; advocates for the expansion of seaweed farms are increasing in many countries. In general, seaweed farms are expected to be highly productive, although whether they are autotrophic or heterotrophic ecosystems and hence potential exporters of carbon, is under debate. Therefore, we present our investigation of three seaweed farms, two in northern Japan and one in southern Japan. We examine the frequency of autotrophic days and compare potential rates of carbon capture of the seaweed farms with two natural macroalgae ecosystems and one degraded site. We estimated potential carbon capture rates by calculating the net ecosystem productivity from continuous recordings of dissolved oxygen concentrations under natural environmental conditions. The net ecosystem production rates for the natural ecosystems in Arikawa Bay and Omura Bay were equivalent to 0.043 and 0.054 [g C m<sup>-2</sup> d<sup>-1</sup>] m<sup>-1</sup>, respectively. Whereas, for the degraded ecosystem in Tainoura Bay, it was -0.01 [g C m<sup>-2</sup> d<sup>-1</sup>] m<sup>-1</sup>. We reveal that the Undaria pinnatifida farm in Matsushima Bay experience autotrophy more often than natural ecosystems, although for seaweed farms producing U. pinnatifida in Hirota Bay and Cladospihon okamuranus at Bise Point, autotrophy was less frequently observed. Nevertheless, up to 14.1 g C m<sup>-2</sup> (0.110 g C m<sup>-2</sup> d<sup>-1</sup>) was captured by the production of U. pinnatifida and 3.6 g C m<sup>-2</sup> (0.034 g C m<sup>-2</sup> d<sup>-1</sup>) was captured by C. okamuranus, and the total yield of carbon captured during 2021 production season for these farms was 43,385 kg C. DOI： 10.3389/fmars.2022.861932
