Discharge variability and its effect on faunistic assemblages in springs
Abstract Discharge variability is an important disturbance factor, and its effect on macroinvertebrate assemblages has been widely studied in river ecosystems. In comparison, few researchers have investigated discharge variability in springs because they are thought to be relatively stable ecosystems and because discharge is not easy to measure in springs. We used the gypsum-dissolution method to assess the discharge regime of 5 natural perennial springs during a 1-y study. We calculated discharge from the mass loss of gypsum spheres at a given temperature after calibration of the method in the laboratory. We also collected seasonal macroinvertebrate samples during the study period to assess the effect of discharge variability on the composition of macroinvertebrate assemblages in the springs. The calibration experiments revealed significant linear relationships between mass loss and discharge. In the field experiments, we were able to differentiate springs with high discharge variability from springs wit...