Ward Juliette N, Pond David W, Murray John W
Southampton Oceanography Centre, Empress Dock, European Way, Southampton, SO14 3ZH, UK.
Mar Environ Res. 2003 Oct;56(4):515-30. doi: 10.1016/S0141-1136(03)00040-0.
Foraminiferal ecology at sewage outfalls has been investigated in numerous field studies over the last 30 years. Foraminifera have been frequently used as biomonitors of sewage pollution since they are both abundant and ubiquitous. Sewage outfalls have been demonstrated to have both positive and negative effects on adjacent foraminiferal populations, but it has never been shown conclusively why sewage affects foraminifera in these ways. Such information on the impact mechanisms of sewage pollution is essential if foraminifera are to be used as sewage pollution biomonitors, and also to understand the ecology of these important protists. One possible cause of a positive effect is the direct consumption of sewage-derived particulate organic matter (POM) by the foraminifera themselves. However this hypothesis has never been tested experimentally. Here, lipid (fatty acid and sterol) biomarker techniques were applied to study the ingestion of two potential food items by the foraminiferan Haynesina germanica in the laboratory. An experiment was conducted to confirm that the laboratory conditions were conducive to the survival and feeding of the foraminifera. In this experiment, foraminifera were provided with the pennate diatom Phaeodactylum tricornutum, which was considered to be a suitable food source. After 2 weeks, a four-fold increase in the levels of the diatom fatty acid biomarker, 20:5(n-3), in the foraminifera suggested that they had fed actively on the diatoms and survived under the experimental conditions. These experimental conditions were used in the main experiment, where foraminifera were fed the POM from sewage. Lipid biomarker analysis indicated that H. germanica did not consume secondary treated sewage-derived POM. Neither fatty acid profiles in the sewage nor coprostanol, the diagnostic human faecal sterol, were detected in foraminifera after exposure to the potential sewage food source. However, foraminifera may have consumed bacteria associated with the sewage in the experiment. The findings are discussed in terms of current EU legislation on sewage treatment that has affected the composition of sewage discharges, and therefore possibly reduced the nutritive value of sewage to the marine benthos.
在过去30年的众多实地研究中，人们对污水排放口处的有孔虫生态进行了调查。由于有孔虫数量丰富且分布广泛，它们经常被用作污水污染的生物监测指标。污水排放口已被证明对相邻的有孔虫种群有正面和负面的影响，但从未确凿地表明污水为何以这些方式影响有孔虫。如果要将有孔虫用作污水污染生物监测指标，并了解这些重要原生生物的生态，那么关于污水污染影响机制的此类信息至关重要。产生积极影响的一个可能原因是有孔虫自身直接消耗源自污水的颗粒有机物质（POM）。然而，这一假设从未经过实验验证。在此，脂质（脂肪酸和甾醇）生物标志物技术被应用于在实验室中研究有孔虫德国海尼西有孔虫对两种潜在食物的摄取情况。进行了一项实验以确认实验室条件有利于有孔虫的生存和摄食。在该实验中，为有孔虫提供了被认为是合适食物来源的角毛藻。两周后，有孔虫体内硅藻脂肪酸生物标志物20:5(n - 3)的水平增加了四倍，这表明它们积极摄食了硅藻并在实验条件下存活了下来。这些实验条件被用于主要实验，在该实验中，给有孔虫投喂来自污水的POM。脂质生物标志物分析表明，德国海尼西有孔虫没有消耗二级处理后的源自污水的POM。在接触潜在的污水食物源后，在有孔虫体内既未检测到污水中的脂肪酸谱，也未检测到诊断性人类粪便甾醇粪甾烷醇。然而，有孔虫在实验中可能消耗了与污水相关的细菌。根据欧盟当前关于污水处理的立法对污水排放成分的影响进行了讨论，因此这可能降低了污水对海洋底栖生物的营养价值。
