ECOLOGICAL FINGERPRINTS IDENTIFY AQUIFER FLOWPATH OF SEWAGE CONTAMINANTS ENTERING ALEXANDER SPRINGS, FLORIDA
Immediately downstream of the spring, the stream is clogged with a dense growth of macrophytes (nuisance and alien species of algae and vascular plants), and a thick dark layer of organic ooze blankets the bottom of the stream channel. These symptoms indicate chronic nutrient-loading and eutrophication of formerly pristine Alexander Springs Run. An independent study using stable nitrogen isotope (d 15N) analysis of these macrophytes revealed signatures indicative of sewage contamination.
The Ocala National Forest surrounds the site, minimizing contaminant introduction via the deeper, regional aquifer system tested by FDEP. Public toilets for the Forest Services Alexander Springs Recreational Area are located up-slope of the FDEP and independent study sites. The ecological fingerprints from this independent study are consistent with nutrient-loading of Alexander Springs Run via lateral flow and groundwater discharge of sewage introduced into the overlying sandy, surficial aquifer from the public toilets. This indicator-species analysis approach can reduce the time and expense of documenting ecologically-significant nutrient-loading from ground water, while identifying the contributing aquifer and the source of the nutrients.