The early colonisation of experimental mesocosms: The role of active and passive dispersal mode

Ephemeral wetlands represented a special type of periodic waters that are often found in intensively agriculturally managed landscapes. This study demonstrates the influence of both soil addition and the presence of Daphnia magna competitor on the development of invertebrate communities in experimental mesocosms. Treatments included rainwater-filled mesocosms with and without the addition of Daphnia magna, and with and without the addition as arable soil serving as a potential egg bank source. The early colonisation was monitored by two subsequent sampling periods with a total exposition time of 42 days. We hypothesised that factors potentially influencing emerging species communities may include the presence and absence of D. magna as a community engineer, as well as the presence and absence of soil fraction. The results showed that the addition of arable soil significantly influenced physico-chemical parameters, increasing conductivity and total nitrogen. Rotifers were the first colonisers, with a higher abundance in treatments with added soil. D. magna survived and established populations only in treatment with added arable soil but did not survive in rainwater only treatment. Chironomids were the most diverse group, with increased abundance and taxa richness over time. The presence of D. magna in the soil-amended treatment resulted in a unique community structure, likely due to its grazing impact on the food web.