Chinese Journal of Oceanology and Limnology Vol. 29 No. 4, P. 775-789, 2011 DOI: 10.1007/s00343-011-0506-8 Sewage pollution in Negril, Jamaica: effects on nutrition and ecology of coral reef macroalgae B. E. LAPOINTE 1, * , K. THACKER 2 , C. HANSON 2 , L. GETTEN 2 1 Harbor Branch Oceanographic Institute at Florida Atlantic University, 5600 US 1 North, Ft. Pierce, FL 34946, USA 2 Negril Coral Reef Preservation Society, P. O. Box 2563, Negril, Jamaica, West Indies Received Mar. 8, 2011; revision accepted Mar. 29, 2011 © Chinese Society for Oceanology and Limnology, Science Press, and Springer-Verlag Berlin Heidelberg 2011 Abstract Coral reefs in the Negril Marine Park (NMP), Jamaica, have been increasingly impacted by nutrient pollution and macroalgal blooms following decades of intensive development as a major tourist destination. A baseline survey of DIN and SRP concentrations, C:N:P and stable nitrogen isotope ratios (δ 15 N) of abundant reef macroalgae on shallow and deep reefs of the NMP in 1998 showed strong P-limitation and evidence of increasing sewage pollution. In 1999, a sewage collection and treatment project began diverting wastewater from the resort and urban areas to a pond system that discharged partially-treated effluent into the South Negril River (SNR). These sewage discharges significantly increased concentrations of NH 4 + and SRP (N:P ~13) in the SNR, which flows into Long Bay and around Negril’s “West End”. Concentrations of SRP, the primary limiting nutrient, were higher on shallow reefs of the West End in 2001 compared to 1998. Stable nitrogen isotope ratios (δ 15 N) of abundant reef macroalgae on both shallow and deep reefs of the West End in 2002 were significantly higher than baseline values in 1998, indicating an escalating impact of sewage nitrogen pollution over this timeframe. The increased nutrient concentrations and δ 15 N enrichment of reef macroalgae correlated with blooms of the chlorophyte Chaetomorpha linum in shallow waters of Long Bay and Codium isthmocladum and Caulerpa cupressoides on deep reefs of the West End. Sewage treatment systems adjacent to coral reefs must include nutrient removal to ensure that DIN and SRP concentrations, after dilution, are below the low thresholds noted for these oligotrophic ecosystems. Keyword: macroalgae; sewage; carbon; nitrogen; phosphorus; stable nitrogen isotopes; eutrophication 1 INTRODUCTION Nutrient pollution from land-based sources is a primary threat to the marine environment of the Caribbean and impediment to sustainable use of its coastal resources (MEA, 2005; UNEP, 2006). Sewage is a major and increasing source of nitrogen (N) and phosphorus (P) pollution and contributes to eutrophication and public health threats along many Caribbean coastlines (Windom, 1992). One common symptom of sewage-driven eutrophication on coral reefs is the development of benthic macroalgal blooms (Barnes, 1973; Johannes, 1975; Smith et al., 1981; Lapointe, 1997; Lapointe et al., 2005a, b). Hermatypic (reef-forming) corals have adapted physiological mechanisms of nutrient recycling that allows these symbiotic calcifying organisms to flourish in clean, clear water with very low concentrations of dissolved inorganic nitrogen (DIN = NH 4 + + NO 3 - + NO 2 - ) and soluble reactive phosphorus (SRP; Muscatine and Porter, 1977; McConnaughey et al., 2000). Accordingly, low level increases in concentrations of DIN or SRP from sewage discharges can stress coral reefs and lead to alternative stable states dominated by fleshy, non-calcifying macroalgae (Smith et al., 1981; Lapointe, 1997; Lapointe et al., 2005a, b). The natural beauty of Negril and surrounding areas on the northwest coast of Jamaica, which included clear waters, fringing coral reefs (Goreau, 1959), and a 10-km long, fine-grained carbonate * Corresponding author: blapoin1@hboi.fau.edu