Sommer Ulrich
Leibniz-Institute of Marine Sciences at Kiel University (IFM-GEOMAR), Düsternbrooker Weg 20, 24105, Kiel, Germany.
Oecologia. 2009 Feb;159(1):207-15. doi: 10.1007/s00442-008-1193-9. Epub 2008 Nov 5.
The feeding selectivity and the growth and reproductive success of the copepod Acartia tonsa have been studied in mesocosms fertilized at different Si:N ratios (0-1.75:1) and, therefore, at different compositions of the phytoplankton communities. Phytoplankton composition showed a strong response to nutrient ratios, with diatoms comprising >90% at Si:N ratios >1:1 of total biomass as opposed to <20% at the lowest ratio. A. tonsa strongly preferred feeding on motile prey (flagellates and ciliates) to feeding on diatoms. Nevertheless, diatoms comprised a substantial part of the diet at the highest Si:N ratios. A. tonsa egg production and the final (after 4 weeks) abundance of adults and copepodites showed no response to Si:N ratios while nauplii production slightly increased with Si:N ratios. It is concluded that the frequently reported deleterious effect of diatoms on copepod reproduction is rather unusual when copepods are confronted with a naturally diverse phytoplankton assemblage instead of clonal cultures in the laboratory.
在不同硅氮比（0 - 1.75:1）施肥的中宇宙中，研究了桡足类中华哲水蚤的摄食选择性以及生长和繁殖成功率，因此，研究了不同浮游植物群落组成情况下的这些指标。浮游植物组成对营养盐比例有强烈响应，当硅氮比大于1:1时，硅藻占总生物量的90%以上，而在最低比例时则低于20%。中华哲水蚤强烈偏好以活动的猎物（鞭毛虫和纤毛虫）为食，而非硅藻。然而，在最高硅氮比时，硅藻在其食物中占相当大的比例。中华哲水蚤的产卵量以及成虫和桡足幼体的最终（4周后）丰度对硅氮比没有响应，而无节幼体的产量随硅氮比略有增加。得出的结论是，当桡足类面对自然多样的浮游植物组合而非实验室中的克隆培养物时，硅藻对桡足类繁殖经常报道的有害影响相当不寻常。
