Red tide is a harmful algal bloom (HAB) that typically forms offshore and produces a toxin that can affect both marine life and humans. Once onshore, it can be exacerbated by human activities, including excessive use of plant fertilizers, littering, and an increasing amount of stormwater runoff from impervious areas.  For more information, please visit the City of Naples Red Tide Page,  or Collier County’s Red Tide Update Page.