Dr. Lapointe presented "Evidence of Wastewater-Driven Eutrophication and Harmful Algal Blooms in the Indian River Lagoon, East-Central, Florida" at the 93rd Florida Annual Meeting and Exposition (FAME) hosted by the Florida Section of the American Chemical Society at the Innisbrook Resort in Palm Harbor, FL.
EVIDENCE OF WASTEWATER-DRIVEN EUTROPHICATION
AND HARMFUL ALGAL BLOOMS IN THE INDIAN RIVER LAGOON, EAST-CENTRAL FLORIDA
Dr. Brian E. Lapointe
ABSTRACT: The Indian River Lagoon (IRL) has experienced problems associated with increasing macroalgal blooms, seagrass epiphytization, and hypoxia/anoxia for decades. Following significant rainfall in Spring 2011 that ended a multi-year drought, a severe “super bloom” of phytoplankton (> 100 µg/L Chl a) developed in the northern IRL. This was followed by a “brown tide” in the northern IRL and Mosquito Lagoon in 2012, which was followed by widespread seagrass die-off and wildlife mortality, including endangered manatees. To better understand the nutrient source(s) and dynamics surrounding these harmful algal blooms (HABs), seawater samples and benthic macroalgae were collected at a network of 20 stations throughout the IRL. High TDN concentrations (up to 152 µM) and TDN:TDP ratios (>100:1) in the poorly flushed northern IRL, Mosquito Lagoon and Banana River segments reflected the accumulation and cycling of N-rich groundwater and surface water inputs that produce P- limitation. Macroalgae d15N values were enriched throughout the IRL (+6.3 o/oo) and similar to values reported for macroalgae from other sewage-polluted coastal waters. Because point-source sewage inputs to the IRL were largely eliminated through the IRL Act of 1990, these results suggest that non-point source N enrichment from septic tanks (300,000-600,000) represents a significant and largely ignored N-source to the IRL. The high degree of sewage N contamination of the IRL, combined with recent HABs, including toxic ecotypes of the red macroalga Gracilaria tikvahiae McLachlan, seagrass loss, and wildlife mortality, indicates a critical need for improved sewage collection and treatment, including nutrient removal.
Studying water quality and harmful algal blooms throughout Florida and the Caribbean.