Limu (Hawaiian marine algae) absorbs nitrogen directly from the ocean, making it a natural record of what’s flowing onto the reef. The maps below show results from our ongoing monitoring along Wailea’s coastline. Explore by tab to see how each site compares across two measurements:
Percent Nitrogen (%N) — How much nitrogen is in the algae tissue. Above 2% indicates excess nitrogen is entering coastal waters.
Nitrogen Isotope (δ¹⁵N) — Helps identify where that nitrogen is coming from. Above 7‰ suggests wastewater influence; lower levels point to fertilizer runoff or other land-based sources.
In our most recent sampling, Polo Beach and Ulua North both showed reductions in nitrogen, a positive sign at two sites we’ve been watching closely.
Want to learn more? Read about our limu monitoring program here.