Browsing by Author "Wiegner, Tracy N."
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Item Detection and Impact of Sewage Pollution on South Kohala's Coral Reefs(2020-03) Aguiar, Devon Kealo; Wiegner, Tracy N.; Tropical Conservation Biology & Environmental ScienceItem Dilution of sewage pollution in the coastal waters of Hilo, Hawaiʻi, USA; an area with high river and groundwater inputs.(2022-08) Nakoa III, Joseph William Paʻakaula; Wiegner, Tracy N.; Tropical Conservation Biology & Environmental ScienceItem Identifying Hotspots of Sewage Pollution in Coastal Areas with Coral Reefs(2016-08) Abaya, Leilani Maijastina; Wiegner, Tracy N.; Tropical Conservation Biology & Environmental ScienceSewage pollution threatens human and coral reef health. Study goals were to identify sewage pollution hotspots through dye tracer tests, measurements of sewage indicators, and development of a sewage pollution score, along Puakō’s (Hawaiʻi) reef. Sewage was localized within 10 m of the shoreline and reached it within 9 hours to 3 days. Shoreline nutrient concentrations were two times higher than upland groundwater. Sewage indicators were higher and more variable along the shoreline than on the reef, and often greater than water quality standards. Shoreline δ15N macroalgal values were indicative of sewage, while offshore values were indicative of soil or groundwater nitrate. A sewage pollution score was created using several indicators that accurately identified sewage pollution hotspots, as three dye tracer locations had the highest scores. Results highlight the need for a multi-indicator approach and scoring system for identifying sewage pollution hotspots to improve water quality.Item Rainfall Driven Shifts in Staphylococcus aureus and Fecal Indicator Bacteria in the Hilo Bay Watershed(2018-05) Economy, Louise Marie; Wiegner, Tracy N.; Tropical Conservation Biology & Environmental ScienceBacteria in nearshore waters can threaten coastal communities, as some land-based bacteria can be pathogenic. The transport of these pathogens to the ocean is largely regulated by rainfall and stream flow patterns. Climate change will impact weather patterns, altering dynamics of pathogen loading to coastal waters. To assess the impact of pathogen loading to nearshore waters under varying weather conditions, a study was conducted in the Hilo Bay watershed in Hilo, Hawai`i, USA. Staphylococcus aureus, Methicillin-Resistant S. aureus (MRSA), and fecal indicator bacteria (FIB, Enterococcus spp. and Clostridium perfringens) were quantified within Hilo Bay and its watershed streams, and within potential landscape sources (road runoff, sewage, and soil), using culture-based methods. Bacteria concentrations were compared to rainfall and stream flow data from pre-existing gauges. S. aureus and FIB were found across all Hilo Bay stations, and within streams, road runoff, sewage, and soil. MRSA was also found within Hilo Bay stations close to shore, and within streams and road runoff, but was less prevalent. S. aureus and FIB were significantly related to rainfall across stations in Hilo Bay. Additionally, S. aureus and FIB concentrations had positive relationships with peak stream discharge, as well as the ratio of current stream flow and the 7-d moving average. These data suggest that more intense storms, and increased dry periods between storms, will increase S. aureus and FIB loads to Hilo Bay. The patterns and models developed in this study will be useful for informing the public of impaired water quality conditions in Hawai`i, and across the wet tropics.Item Shifts in Carbon Flux from a Hawaiian Watershed due to Climate Change(2023-12) Boger, Walter Loc-Ming; Wiegner, Tracy N.; Tropical Conservation Biology & Environmental ScienceItem SPATIAL DISTRIBUTION AND SOURCES OF NUTRIENTS AT TWO COASTAL DEVELOPMENTS IN SOUTH KOHALA, HAWAI‘I(2020-12) Panelo, Jazmine R.; Wiegner, Tracy N.; Tropical Conservation Biology & Environmental ScienceNon-point sources of nutrients to coastal waters are not well-characterized for watersheds with coral reefs, which are vulnerable to excess nutrient inputs. Objectives of this study were to: 1) document the spatial distributions of nutrient concentrations within nearshore waters along two coastal developments with fringing coral reefs, and 2) identify nutrient sources in these bays by: measuring nutrient concentrations, developing nutrient mixing plots, assessing 15 of nitrogen (N) in macroalgal tissue, and developing 15N and 18O of NO3- stable isotope mixing models. Our results indicate that nutrient concentrations decreased from fresh groundwater to offshore waters. Within the bays, nutrient concentrations were higher at the shoreline and decreased offshore, with some surface waters higher in concentrations than benthic ones. There was conservative and non-conservative mixing between fresh and ocean waters within the bays, with the latter suggesting local nutrient sources and biological removal. Stable N isotopes in algal tissue and NO3- concurred revealing that fresh groundwater, ocean water, and fertilizers were dominant N sources in the bays. The significant relationship between benthic salinity and NO3- + NO2- concentrations demonstrated that submarine groundwater discharge (SGD) was an important nutrient source to reefs at both bays. Data from benthic conductivity loggers assessed salinity trends and the length of time that nutrients obtained from groundwater stayed on the benthos, revealing that nutrients were delivered to the reefs through SGD pulses, ranging from a few min to 2 d. These findings allow for the identification of reef areas more susceptible to nutrient pollution that may be susceptible to increased algal growth. Quantifying nutrient concentrations and identifying their sources in areas with coral reefs is imperative for reducing land-based nutrient loads, which may make the reefs to be more resilient to more global stressors.Item TROPHIC PLASTICITY IN SCLERACTINIAN CORALS: A META-ANALYSIS USING INNOVATIVE TEXT ANALYTIC TOOLS(2021-12) McSwain, Dawn; Wiegner, Tracy N.; Tropical Conservation Biology & Environmental Science