Effects of increased pCO2 and temperature on the North Atlantic spring bloom. I. The phytoplankton community and biogeochemical response
Effects of increased pCO2 and temperature on the North Atlantic spring bloom. I. The phytoplankton community and biogeochemical response
复制标题
pCO2 和温度增加对北大西洋春季水华的影响。
DOI：
10.3354/meps08133
复制
发表时间：
2009-01-01
影响因子：
2.5
通讯作者：
Hutchins, David A.
中科院分区：
文献类型：
--
作者：
Feng, Yuanyuan;Hare, Clinton E.;Hutchins, David A.
北大西洋春季水华是海洋中最大的年度生物事件之一，其特点是从硅质(硅藻)藻类向钙质(球藻)藻类的优势过渡。为了研究未来全球变化对这些浮游植物的影响及其所介导的生物地球化学循环，2005年6月在这一过渡期内进行了船上连续培养实验(ECOST)。试验分四个处理：(1)12摄氏度和390ppm二氧化碳(环境对照)；(2)12摄氏度和690ppm二氧化碳(高二氧化碳浓度(2))；(3)16摄氏度和390ppm二氧化碳(高温)；(4)16摄氏度和690ppm二氧化碳(温室)。所有处理的养分利用率都被设计成重现花朵后期典型的低硅酸盐条件。PCO(2)升高和温度升高都会引起浮游植物群落结构的变化。温度升高促进了整个群落的光合作用和单位叶绿素a的颗粒有机碳(POC)产生速率。尽管温室处理中球藻生物体的丰度大大增加，但由于PCO(2)和温度的增加，颗粒无机碳的产生(钙化)显著减少。我们的实验表明，在水华期间，未来的趋势可能包括与POC相比，碳酸钙的出口大大减少，从而对大气中的二氧化碳浓度提供潜在的负反馈。具有潜在气候反馈效应的其他趋势包括较高温度下群落生物成因二氧化硅与POC比率的降低。这些船上实验表明，有必要研究未来二氧化碳浓度和气温在更长的十年时间尺度上的上升是否会同样改变北大西洋春季水华的生物和生物地球化学动态。
The North Atlantic spring bloom is one of the largest annual biological events in the ocean, and is characterized by dominance transitions from siliceous (diatoms) to calcareous (coccolithophores) algal groups. To study the effects of future global change on these phytoplankton and the biogeochemical cycles they mediate, a shipboard continuous culture experiment (Ecostat) was conducted in June 2005 during this transition period. Four treatments were examined: (1) 12 degrees C and 390 ppm CO2 (ambient control), (2) 12 degrees C and 690 ppm CO2 (high pCO(2)) (3) 16 degrees C and 390 ppm CO2 (high temperature), and (4) 16 degrees C and 690 ppm CO2 ('greenhouse'). Nutrient availability in all treatments was designed to reproduce the low silicate conditions typical of this late stage of the bloom. Both elevated pCO(2) and temperature resulted in changes in phytoplankton community structure. Increased temperature promoted whole community photosynthesis and particulate organic carbon (POC) production rates per unit chlorophyll a. Despite much higher coccolithophore abundance in the greenhouse treatment, particulate inorganic carbon production (calcification) was significantly decreased by the combination of increased pCO(2) and temperature. Our experiments suggest that future trends during the bloom could include greatly reduced export of calcium carbonate relative to POC, thus providing a potential negative feedback to atmospheric CO2 concentration. Other trends with potential climate feedback effects include decreased community biogenic silica to POC ratios at higher temperature. These shipboard experiments suggest the need to examine whether future pCO2 and temperature increases on longer decadal timescales will similarly alter the biological and biogeochemical dynamics of the North Atlantic spring bloom.