By looking at the bugs in streams, rivers, ponds and lakes we can determine the health of that water source. Specifically we can look at the Benthic-Macro Invertebrates (BMI's) as indicators:
Benthic = Bottom-Dwelling
Macro = Visible to the Naked Eye
Invertebrate = Without a Backbone
BMI's are great indicators of the health of a stream. If we examine what types of bugs and how many of each kind are present in the water we can determine the health of the stream. These little bugs are gauges of the health of the stream for several reasons.
Bio-Monitoring essentially means counting the bugs in the water to determine the water quality, but there are specific protocols to collecting the bugs which we need to follow to make the study accurate.