Filter addresses two aquatic invasive species; zebra and quagga mussels, which have invaded the Great Lakes and are moving inexorably across North American freshwaters. These colonizing filter feeders disrupt the food web, damaging fisheries and creating unhealthy algal blooms.  This piece reflects the fragility of this once abundant ecosystem by contrasting the delicate nature of plankton and native algae with the vigorous lifecycle of these prolific mussels.