Clear Waters?

The invasive zebra mussel (Dreissena polymorpha) has been credited in the past for its ability to increase water clarity, but this may not last for much longer. According to this report from ScienceDaily, a study of Michigan lakes found that zebra mussel invasions cause an increase in blooms of the toxic blue-green algae Microcystis. Interestingly, this is true only for lakes with low to normal nutrient levels; those plagued with high levels of phosphorus due to an influx of runoff from farms or sewage did not have the same problem. Blooms of Microcystis algae have been known to kill animals and cause liver damage in humans.