 Phosphorus is a fertilizer that alters Everglades ecosystems, allowing invasive and exotic cattails to replace sawgrass when levels rise above 50 parts per billion  .
<coherence>  Phosphorus is a fertilizer that alters Everglades ecosystems, allowing invasive and exotic cattails to replace sawgrass when levels rise above 50 parts per billion  .
 Phosphorus alters Everglades ecosystems, allowing invasive and exotic cattails to replace sawgrass when levels rise above 50 parts per billion .