In 1996, NOAA researchers injected two dyes underground near Key Largo to trace groundwater movement; 18 days later, two wells by the bay indicated it was heading toward the Atlantic.

This passage details a 1996 study conducted by NOAA and the US Geological Survey in Key Largo to investigate groundwater movement beneath the Florida Keys. The research was motivated by signs of coral reef decline attributed to factors like water quality and nutrient contamination.

Key Points:

1. Background Context:

   • Coral reefs in the Florida Keys faced deterioration due to various reasons.
   • Scientists suspected that contaminants might be transported into the reefs via groundwater.

2. Methodology:

   • Researchers bored paired monitoring wells into limestone on both sides of Key Largo.
   • They used two fluorescent dyes (rhodamine and fluorescein) to trace groundwater flow.

3. Findings:

   • Dyes were detected in wells facing the Atlantic just 18 days after injection, indicating that groundwater generally flows from Florida Bay towards the Atlantic Ocean.
   • The observed flow was driven by a slight variation in water levels between the two bodies of water.

4. Significance:

   • Groundwater could potentially transport nutrients and contaminants to the coral reefs, showing a physical connection between land and ocean environments.
   • This understanding highlights the need to consider groundwater dynamics in reef conservation efforts.

The experiment illustrated the importance of groundwater pathways in the health of coral ecosystems and emphasized that managing reef environments requires a holistic view of both water sources and potential contaminants.