Algal δ¹⁵N values detect a wastewater effluent plume in nearshore and offshore surface waters and three-dimensionally model the plume across a coral reef on Maui, Hawai‘i, USA

Dailer, Meghan L.; Ramey, Hailey L.; Saephan, Stephanie; Smith, Celia M.

Algal δ¹⁵N values detect a wastewater effluent plume in nearshore and offshore surface waters and three-dimensionally model the plume across a coral reef on Maui, Hawai‘i, USA

2012

Dailer, Meghan L. | Ramey, Hailey L. | Saephan, Stephanie | Smith, Celia M.

The coral reef at Kahekili, Maui is located ∼300m south of the Lahaina Wastewater Reclamation Facility which uses four Class V injection wells to dispose of 3–5million gallons of wastewater effluent daily. Prior research documented that the wastewater effluent percolates into the nearshore region of Kahekili. To determine if the wastewater effluent was detectable in the surface waters offshore, we used algal bioassays from the nearshore region to 100m offshore and throughout the water column from the surface to the benthos. These algal bioassays documented that significantly more wastewater effluent was detected in the surface rather than the benthic waters and allowed us to generate a three-dimensional model of the wastewater plume in the Kahekili coastal region. Samples located over freshwater seeps had the highest δ¹⁵N values (∼30–35‰) and the effluent was detected in surface samples 500m south and 100m offshore of the freshwater seeps (∼8–11‰).

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