An artificial stream mesocosm to simulate fate and effects of chemicals: Technical data and initial experience with the biocenosis

Abstract An artificial stream system is described which has been installed at the Fraunhofer Institute to simulate fate and effects of environmental chemicals in relevant water compartments. The artificial stream is part of the institute's outdoor field simulation facilities for studies with radio-labelled substances. The circular stream system has a length of about 35 m, a width of 0.6 m, a depth of 0.35 m and is made of stainless steel to avoid contaminations. Two inlets and an extended segment diversify the current. Current is generated by electrically-driven steel paddles which allows a regulation of velocity. The artificial stream is filled with sediment (about 2.5 m 3 ) and water (approx. 3 m 3 ) from a small natural stream. Each of the inlets contains an aquatic lysimeter with an undisturbed sediment core of 0.6 m diameter and 0.6 m column height, which is flanged at the bottom of the water basin. This design allows the study of fate of substances in the ecosystem compartments water, sediment and water leaching through the river bed. A preliminary study was performed comparing various physical-chemical water parameters and the development of the biocenosis in the natural and the artificial stream in order to determine whether the natural stream can serve as reference stream in experiments. Following an adaptation period of 4–8 weeks, macroinvertebrate species diversity and population densities were similar in both streams. Therefore, it is concluded that the natural stream can be used as control in future investigations. Exposure studies are planned including investigations of adverse effects of contaminants on organisms transferred to the artificial stream from a natural water.