A 21-year time series of phytoplankton community structure was analysed in relation to Phaeocystis spp. to elucidate its contribution to the annual carbon budget at station L4 in the western English Channel (WEC).

Between 1993–2014 Phaeocystis spp. contributed ∼4.6% of the annual phytoplankton carbon and during the March − May spring bloom, the mean Phaeocystis spp. biomass constituted 17% with a maximal contribution of 47% in 2001. Upper maximal weekly values above the time series mean ranged from 63 to 82% of the total phytoplankton carbon (∼42–137 mg carbon (C) m⁻³) with significant inter-annual variability in Phaeocystis spp. Maximal biomass usually occurred by the end of April, although in some cases as early as mid-April (2007) and as late as late May (2013).

The effects of elevated pCO₂ on the Phaeocystis spp. spring bloom were investigated during a fifteen-day semi-continuous microcosm experiment. The phytoplankton community biomass was estimated at ∼160 mg C m⁻³ and was dominated by nanophytoplankton (40%, excluding Phaeocystis spp.), Phaeocystis spp. (30%) and cryptophytes (12%). The smaller fraction of the community biomass comprised picophytoplankton (9%), coccolithophores (3%), Synechococcus (3%), dinoflagellates (1.5%), ciliates (1%) and diatoms (0.5%). Over the experimental period, total biomass increased significantly by 90% to ∼305 mg C m⁻³ in the high CO₂ treatment while the ambient pCO₂ control showed no net gains. Phaeocystis spp. exhibited the greatest response to the high CO₂ treatment, increasing by 330%, from ∼50 mg C m⁻³ to over 200 mg C m⁻³ and contributing ∼70% of the total biomass.

Taken together, the results of our microcosm experiment and analysis of the time series suggest that a future high CO₂ scenario may favour dominance of Phaeocystis spp. during the spring bloom. This has significant implications for the formation of hypoxic zones and the alteration of food web structure including inhibitory feeding effects and lowered fecundity in many copepod species.

分析了21年浮游植物群落结构与Phaeocystis spp的关系。阐明其对西部英吉利海峡（WEC）L4站的年度碳预算的贡献。

与1993年至2014年棕囊藻属。贡献了约4.6％的年度浮游植物碳，在3月至5月的春季开花期间，Phaeocystis spp的平均值。生物量占17％，最大贡献量为2001年的47％。高于时间序列平均值的每周最大上限值介于浮游植物总碳（约42-137 mg碳（C）m ^-3）的63％至82％之间，囊藻属物种的年际变化。最大的生物量通常在4月底出现，尽管在某些情况下早在4月中旬（2007）和5月下旬（2013）。

pCO ₂升高对Phaeocystis spp的影响。在十五天的半连续缩影实验中研究了春季开花。浮游植物群落生物量估计为~160毫克C M ^-3和由浮游植物为主（40％，不包括棕属物种），棕属。（30％）和隐生植物（12％）。社区生物质的较小部分包括微浮游生物（9％），球墨镜（3％），滑球菌（3％），鞭毛虫（1.5％），纤毛虫（1％）和硅藻（0.5％）。在实验期间，在高CO _2中，总生物量显着增加了90％，达到约305 mg C m ^-3。周围pCO ₂对照无净增值。囊藻属 对高CO ₂处理表现出最大的响应，从约50 mg C m ^-3增加到超过200 mg C m ^-3增加330％，并贡献了约70％的总生物量。

两者合计，我们的缩影实验和时间序列分析的结果表明，未来的高CO ₂情景可能会有利于Phaeocystis spp。在春天盛开。这对缺氧区的形成和食物网结构的改变具有重要意义，包括抑制feeding食作用和降低许多co足类物种的繁殖力。