| 摘要: |
| 在许多水体生态系统中，浮游植物的生长受到营养盐可利用性的调控(Howarth，1988)。在一定的浓度范围内，营养盐对浮游植物的生长有促进作用，但如果营养盐浓度过低，则会对浮游植物的生长产生限制作用，过高则有毒理作用。
由于人类活动的影响，导致大量富含N、P的工业与生活污水排放入海水中，造成沿岸海水的富营养化。营养盐本底含量的增加对沿岸海水中浮游植物群落的组成影响巨大(Durate，1995)。Pedersen等(1996)指出，在沿岸海洋生态系统中，富营养化的结果会促进生长快速、生活周期短的藻类的丰度与生产力迅速增加，而生长缓慢的藻类由于在竞争中处于劣势，其丰度则可能下降。
在海洋生态系统中，用瓶子培养实验和化学计量法所得出的营养盐限制结论经常出现差异。溶解营养盐的浓度被最早用来指示营养盐的限制性，这些主要基于一些负的实验证据，例如，当磷酸盐仍然可测时，溶解硝酸盐已经检测不到 (Nixon et al.，1983)，暗示N可能比P更限制浮游植物的生长。但是在营养盐浓度无法检测得到的情况下，仍然有许多浮游植物种类对N、P有很高的亲和能力，因此藻的生长并未受到营养盐的限制。本实验应用是瓶子培养实验，该方法的优点是现场操作，光照和温度条件与现场基本一致，通过生物方法来反应营养盐的限制作用，结果可信度较高。本论文研究的目的是观察胶州湾浮游植物对营养盐添加的响应效果，以期对胶州湾营养盐限制研究提供有价值的科学信息。 |
| 关键词: 胶州湾 营养盐 |
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| Bottom-up Effect Studies of Nutrient Limitation of Phytoplankton in Jiaozhou Bay |
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WANG Yong1, ZHOU Yi1, SUN Hekun2
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1.Institute of Oceanology, The Chinese Academy of Sciences;2.Environmental Protection Bureau of Qingdao
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| Abstract: |
| In order to investigate nutrient limitation of phytoplankton in natural marine ecosystems, in-situ nutrient enrichment experiments with nitrate, ammonium, phosphate and iron addition were conducted in Jiaozhou Bay in August November, 1999 and February May and August, 2000. Jiaozhou Bay, surrounded by Qingdao city and with area of 390 km2 and mean depth of 7m is an eutrophic coastal bay. The concentrations of nitrate, ammonium and phosphate were 1.98, 8.01and 1.38 μmom/L in the 1999s. DIN: P molar ratio was almost always over 16 (the Redfield ratio, also called “geochemically balanced”) in all seasons.
Five nutrient enrichment experiments were conducted to investigate nutrient limitation on phytoplankton. Size-fractionated chlorophyll-a results showed that netphytoplankton (20-200μmom/L) showed most significant response to N addition; nanophytoplankton (2-200μmom/L) showed significant response to P addition, but N addition also stimulated their growth; picophytoplankton (<2μmom/L) showed positive response to N or P addition, but this response was not more significant than that of netplankton or nanoplankton. N probably Limited phytoplankton growth in summer, but P and N nutrient could phytoplankton growth in other seasons in Jiaozhou Bay. |
| Key words: nutrient limitation Jiaozhou Bay N P |
