The present study performed in Horten Inner Harbor (southern Norway) shows that foraminifera link the present-day Ecological Quality Status (EcoQS) to EcoQS of former times and, this way, bridge an important knowledge gap concerning determination of reference conditions, even in naturally stressed environments such as transitional waters and oxygen depleted habitats. In Horten Inner Harbor, geochemical data in the oldest deposits showed stable background concentrations for about 200 years (from about 1600 to 1800) before human activity became noteworthy, reflecting ‘good’ to ‘high’ status. Hence, it is reasonable that organisms, which lived in the area during the same un-impacted time interval, represent the biologically defined reference conditions, irrespectively of whether the biotic indices are classified as ‘good’ or ‘bad’. The present paper illustrates, with a conceptual model, how the retrospective foraminiferal biomonitoring method can be used to detect environmental perturbations in estuaries and meet the difficulties of the Estuarine Quality Paradox.

在霍滕内港（挪威南部）进行的本研究表明，有孔虫将当今的生态质量状况（EcoQS）与以前的EcoQS联系起来，从而弥合了有关确定参考条件的重要知识鸿沟，即使是自然界压力环境，例如过渡水和氧气耗尽的栖息地。在霍滕内港，最古老矿床的地球化学数据显示，在人类活动变得值得注意之前，背景浓度一直稳定了约200年（从1600年到1800年），反映了“好”至“高”状态。因此，合理的是，在相同的不受影响的时间间隔内生活在该区域中的生物代表了生物学定义的参考条件，而与生物指标是“好”还是“坏”无关。本文通过概念模型说明了追溯性有孔虫生物监测方法如何可用于检测河口中的环境扰动并解决河口质量悖论的难题。