Phytoplankton production in coastal waters influences seafood production and human health and can lead to harmful algal blooms. Water temperature and eutrophication are critical factors affecting phytoplankton production, although the combined effects of warming and nutrient changes on phytoplankton production in coastal waters are not well understood. To address this, phytoplankton production changes in natural waters were investigated using samples collected over eight months, and under 64 different initial conditions, established by combining four different water temperatures (i.e., ambient T, +2, +4, and + 6 °C), and two different nutrient conditions (i.e., non-enriched and enriched). Under the non-enriched conditions, the effect of warming on phytoplankton production was significantly positive in some months, significantly negative in others, or had no effect. However, under enriched conditions, warming affected phytoplankton production positively in all months except one, when the salinity was as low as 6.5. These results suggest that nutrient conditions can alter the effects of warming on phytoplankton production. Of several parameters, the ratio of initial nitrate concentration to chlorophyll a concentration [NCCA, μM (μg L⁻¹)⁻¹] was one of the most critical factors determining the directionality of the warming effects. In laboratory experiments, when NCCA in the ambient or nutrient-enriched waters was ≥1.2, warming increased or did not change phytoplankton production with one exception; however, when NCCA was <1.2, warming did not change or decreased production. In the time series data obtained from the coastal waters of four target countries, when NCCA was 1.5 or more, warming increased phytoplankton production, whereas when NCCA was lower than 1.5, warming lowered phytoplankton production, Thus, it is suggested that NCCA could be used as an index for predicting future phytoplankton production changes in coastal waters.

沿海水域的浮游植物生产影响海产品生产和人类健康，并可能导致有害的藻华。尽管升温和养分变化对沿海水域浮游植物产量的综合影响尚不十分清楚，但水温和富营养化是影响浮游植物产量的关键因素。为了解决这个问题，我们使用八个月内收集的样本调查了自然水域浮游植物的生产变化，并在64种不同的初始条件下建立了四个不同的水温（即环境温度T，+ 2，+ 4和+ 6°C） ）和两种不同的营养条件（即未富集和富集）。在非富营养条件下，变暖对浮游植物产量的影响在某些月份显着为正，而在另一些月份则显着为负，或没有任何效果。但是，在富营养条件下，变暖对所有月份的浮游植物产量都产生了积极影响，唯一的一个例外是盐度低至6.5时。这些结果表明营养条件可以改变变暖对浮游植物产量的影响。在几个参数中，初始硝酸盐浓度与叶绿素的比率一个浓度[NCCA，μM（微克大号^-1）^-1 ]为的确定的温暖效果方向性的最关键因素之一。在实验室实验中，当环境或营养丰富的水中的NCCA≥1.2时，变暖增加或没有改变浮游植物的产量，只有一种例外；但是，当NCCA <1.2时，变暖并没有改变或减少产量。在从四个目标国家的沿海水域获得的时间序列数据中，当NCCA为1.5或更高时，变暖增加了浮游植物的产量，而当NCCA低于1.5时，变暖降低了浮游植物的产量，因此，建议可以使用NCCA。作为预测沿海水域未来浮游植物产量变化的指标。