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Sewage pollution is contributing to the global decline of coral reefs. Identifying locations where it is entering waters near reefs is therefore a management priority. Our study documented shoreline sewage pollution hotspots in a coastal community with a fringing coral reef (Puakō, Hawai'i) using dye tracer studies, sewage indicator measurements, and a pollution scoring tool. Sewage reached shoreline waters within 9 h to 3 d. Fecal indicator bacteria concentrations were high and variable, and δ 15 N macroalgal values were indicative of sewage at many stations. Shoreline nutrient concentrations were two times higher than those in upland groundwater. Pollution hotspots were identified with a scoring tool using three sewage indicators. It confirmed known locations of sewage pollution from dye tracer studies. Our study highlights the need for a multi-indicator approach and scoring tool to identify sewage pollution hotspots. This approach will be useful for other coastal communities grappling with sewage pollution. [ABSTRACT FROM AUTHOR]

Sewage pollution from on-site sewage disposal systems and injection wells is impacting coral reefs worldwide. Our study documented the presence and impact of sewage on South Kohala's coral reefs, on Hawai'i Island, through benthic water quality and macroalgal sampling (fecal indicator bacteria, nutrients, δ15N macroalgal tissue), NO 3 − stable isotope mixing models, water motion measurements, and coral reef surveys. Sewage pollution was moderate on the offshore reef from benthic seeps, and water motion mixed and diluted it across the benthos. These conditions likely contribute to the dominance of turf algae cover, and the severity and prevalence of growth anomalies and algal overgrowth on corals. Use of multiple indicators and studying water motion was necessary to assess sewage pollution and identify environmental drivers associated with impaired coral health conditions. Methods used in this study can be utilized by natural resource managers to identify and reduce anthropogenic stressors to coral reefs. • Water quality, currents, and benthic surveys assessed coral reef sewage pollution. • Sewage pollution was moderate on the coral reefs from benthic seeps. • Water motion mixed and diluted sewage across the coral reefs. • Sewage presence was associated with coral growth anomalies and algal overgrowth. • Multiple tools identified environmental drivers associated with coral reef impairment. [ABSTRACT FROM AUTHOR]

Nutrient sources to coastal waters with coral reefs are not well-characterized. This study documented spatial distributions of nutrients within coastal waters along two developments with coral reefs, and identified nutrient sources through nutrient mixing plots, δ15N measurements in macroalgal tissue, and NO 3 − stable isotope mixing models. Nutrients decreased from fresh groundwaters to offshore waters, with some surface waters higher in concentrations than benthic ones. Conservative and non-conservative mixing between fresh and ocean waters occurred, the latter suggestive of local nutrient sources and biological removal. δ15N in macroalgal tissue and NO 3 − concurred that fresh groundwater, ocean water, and fertilizers were dominant nutrient sources. Benthic salinity and NO 3 − + NO 2 − concentrations illustrated that submarine groundwater discharge delivered nutrients to reefs in pulses ranging from minutes to days. Information generated from this study is imperative for developing management actions to improve water quality and make coral reefs more resilient to stressors. • Mixing plots, isotopes, and sensors assessed nutrient patterns on resorts' coral reefs. • Nutrients decreased from fresh groundwaters to offshore waters in resorts' watersheds. • Nutrients mixed conservatively and non-conservatively between fresh and ocean waters. • Groundwater, ocean, and fertilizer were dominate nutrient sources to coral reefs. • Submarine groundwater discharge delivered nutrients to reefs in pulses of min to days. [ABSTRACT FROM AUTHOR]

The article discusses a study on the immune defenses of healthy, bleached and yellow band disease (YBD) diseased Montastraea faveolata colonies with natural thermal stress in Puerto Rico. The monitoring was conducted from October 2005 to July 2007 on Turromote Reef, La Parguera. By October 2006, 90% of the bleached colonies became infected with YBD. The colonies were classified as bleached due to their fewer zooxanthellae. The article suggests temperature-induced modifications of allelopathic interactions to foster bacteria susceptibility in coral holobiont.