Puerto Rico-Science & Health
  • This April 1, 2005 file photo shows the Fajardo Grand Lagoon at the Nature Reserve of Las Cabezas de San Juan at dawn, about 35 miles east of San Juan, Puerto Rico.

    Theories range from an increase in construction runoff to inclement weather to people clearing mangroves.

    LAST UPDATE : Nov 20, 2013, 10:38 AM EST