BRC-BIO: High nutrient submarine groundwater discharge delivery effects on coastal primary productivity on coral reefs in Maunalua Bay, Hawaii

Pepperdine University, Malibu CA

Investigators

Abstract

Evaluating the effects of multiple stressors on coastal community dynamics is crucial. In doing so, researchers can understand the resilience of these ecosystems, prepare coastal management for future scenarios, and aid in prioritizing restoration efforts. With at least 52% of the US population living in areas that drain into coastal watersheds, it is imperative for researchers to study the effects of nutrient pollution in coastal systems. Submarine groundwater discharge (SGD) is defined as any and all flow of water from the seabed to the coastal ocean. In areas where the nutrient concentration of coastal groundwater has been substantially increased by changing land use, nutrient loading to coastal waters via SGD has been associated with algae blooms and shifts in the community composition. This research will characterize land-based sources of nutrient pollution and its effects on coral reef productivity and community composition. The results from this research will be shared with state entities. Additionally, the results will aid a non-profit organization focused on restoring the study site in identifying and prioritizing restoration sites. This program will engage up to 10 undergraduates and one post baccalaureate. Peer-reviewed strategies for recruitment and retainment of underrepresented minority students, such as financial incentives and summer-long field-based research, will be used. Maunalua Bay (O‘ahu, HI) has experienced dramatic development and increase in population over the last 100 years. This has affected the water quality in near shore coral reefs. Due to the range of onsite sewage disposal systems density, discrete SGD, and its coral reef habitats, Maunalua Bay is a model system to study land-based effects on water quality and primary production on coral reef communities. The main source of land-based inorganic nutrients in Maunalua Bay is SGD, which delivers both freshwater and inorganic nutrients. This research will use novel methods to characterize SGD delivery to both the water column (drone thermal imagery) and benthos (sensors moored to the reef) of two reefs. The work will also quantify carbon uptake of the main primary producers on algal-dominated reefs. Finally, the productivity of the algae on a reef with SGD and without SGD will be modeled. This work will clarify the magnitude of the effect of SGD on both benthic and water column algal productivity of reefs. More than just understanding the abundance, distribution, and productivity of coastal organisms, the proposed research will get to the physical and chemical mechanisms driving these patterns on a local and regional scale in coral reef ecosystems. This project is cofunded by the Building Research Capacity of New Faculty in Biology Program in the Division of Environmental Biology and the Division of Biological Infrastructure and Biological Oceanography Program in the Division of Ocean Sciences. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.