Measuring diversity: looking for processes that generate diversity

In this study, we compare the variations of Margalef K and Shannon H diversity indices obtained for a fish community that suffered changes as a consequence of the impoundment of the upper Tocantins River in Goiás, Brazil. The analysis of different sites along the study area showed that the Shannon index was not sensitive to the environmental changes, whereas the Margalef K index varied significantly following the impoundment. Therefore, the Margalef K index appears to be a good diversity indicator as well as a valuable parameter for the temporal data series analysis, from changing environments and for the conservation of natural environments. Although the Margalef K index can be used as a diversity index, it can also be used to consistently indicate the speed of ecosystem evolution.