ABSTRACT Some species of Rhizosolenia form intense blooms, known as red tides, in Japanese coastal waters. In Tokyo Bay, Rhizosolenia setigera frequently causes red tides and sometimes causes discolouration of Pyropia in nori farms. However, little is known about the growth characteristics of R. setigera in Tokyo Bay. We evaluated the effects of temperature, salinity, and irradiance on the growth of R. setigera isolated from Tokyo Bay. Our strain grew well in SWM-3 medium and f/2 + N, P, Si, Tris medium, at 5–30 °C and salinity (S) of 20–40. Maximal growth rate was obtained at 25 °C and S of 30–35. The strain maintained a moderate growth rate (0.4 < µ < 0.6) at low temperature (c. 10–13 °C) and S of 30. The strain grew at a wide range of irradiances from 11 to 1625 μmol photons m−2 s−1, with optimum irradiance (L max) ≥ 1625 μmol photons m−2 s−1. In Tokyo Bay from 2010 to 2014, R. setigera was observed at 17.1 to 26.4 °C with S ranging from 24.6 to 31.2, and cell densities exceeding 500 cells ml−1. This corresponded to results from our culture experiments. We anticipate that the data obtained in this study may be useful for understanding the bloom dynamics of R. setigera and the underlying environmental conditions associated with nori discolouration.

中文翻译：

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温度、盐度和光照强度对日本硅藻 Rhizosolenia setigera 生长的影响

摘要 一些根瘤菌在日本沿海水域形成强烈的水华，称为赤潮。在东京湾，Rhizosolenia setigera 经常引起赤潮，有时还会导致海苔养殖场的 Pyropia 变色。然而，人们对东京湾 R. setigera 的生长特征知之甚少。我们评估了温度、盐度和辐照度对从东京湾分离的 R. setigera 生长的影响。我们的菌株在 SWM-3 培养基和 f/2 + N、P、Si、Tris 培养基中生长良好，温度为 5–30 °C，盐度 (S) 为 20–40。在 25 °C 和 S 为 30-35 时获得最大增长率。该菌株在低温 (c. 10–13 °C) 和 S 为 30 下保持适度的生长速率 (0.4 < µ < 0.6)。该菌株在从 11 到 1625 μmol 光子 m-2 s 的广泛辐照度下生长−1, 最佳辐照度 (L max) ≥ 1625 μmol 光子 m−2 s−1。2010 年至 2014 年在东京湾，R. setigera 在 17.1 至 26.4 °C 下观察到，S 范围为 24.6 至 31.2，细胞密度超过 500 个细胞 ml-1。这与我们的培养实验结果一致。我们预计本研究中获得的数据可能有助于了解 R. setigera 的开花动态以及与紫菜变色相关的潜在环境条件。