Invasive macroalgae are chronically widespread in watersheds where disease rates and Nitrogen-footprint values are elevated.

<p><i>A</i>, GWR predicted disease rates and Nitrogen-footprints grouped by island. Oahu points are clustered (87%, 48/55) in quadrants II and III, on Maui points are clustered in quadrants I and II (94%, 15/16), and Hawaii points are clustered in quadrant III (82%, 9/11). <i>B</i>, Disease and Nitrogen-footprints are elevated where macroalgae is chronic and widespread, seen as most points are in quadrant II (88%, 35/40). Green turtles now consume nonnative macroalgae which likely sequester environmental N as arginine. Arginine is known to regulate herpesviruses and contribute to tumor formation.</p>