RAPID: Tracking the impact of engineered system failures on nearshore nutrient loads and harmful algal blooms using multiple stable isotopes

Beaches, bays, and other coastal systems provide valuable recreation opportunities for swimming, fishing, boating and tourism. Fish, shellfish, dolphins, and other animals depend on the seagrasses, coral, algae, and other organisms in these balanced ecosystems to survive. When seagrasses are unhealthy, the rest of the system can suffer, and these benefits can be lost.

Nutrient loading to these environments can increase due to waste discharge and other sources, causing an imbalance in the fragile ecosystem. Sometimes the extra nutrients can cause microscopic phytoplankton to grow rapidly or “bloom” and smother seagrasses and corals. Some types of algal blooms can produce toxins that harmful to wildlife and people that are known as harmful algal blooms or “HABs”.

In late March to early April 2021, concerns were raised about the stability of a reservoir containing wastewater from a defunct fertilizer plant in Piney Point, Florida. These concerns prompted the release of 215 million gallons of waste into Tampa Bay to prevent the reservoir from collapsing. The wastewater contains large concentrations of nutrients that may upset the balance in the coastal receiving waters, causing algal blooms and possibly HABs.

Damage to this ecosystem is especially concerning because Tampa Bay has been a seagrass restoration success story since the 1990s. To address these concerns, research will use advanced scientific tools to specifically track the transport of nutrients from the wastewater to determine their impact on local seagrasses. Successful completion of this research will benefit society by helping water management professionals determine how to mitigate the impacts of excess nutrient loading and better protect these valuable ecosystems.

Additional benefits will result from increased scientific literacy through outreach with local estuary monitoring groups to inform residents about the specific ways that nutrient-rich wastes impact their coastal ecosystems.

The release of nutrients along the Nation’s coastlines represents a chronic threat to nearshore ecosystems. Impacts from increased nutrient loading range from eutrophication, harmful algal blooms, and the production of hypoxic zones. Discharges from a reservoir containing wastewater from a defunct fertilizer plant at Piney Point, Florida has garnered national attention as it threatens estuaries in the Tampa Bay region.

The release of 215 million gallons of nitrogen and phosphorus-rich effluent threatens an ecosystem that has been considered a seagrass restoration success story. A major concern is that these discharges may trigger macroalgae and/or phytoplankton blooms, thereby threatening the ecologically and economically valuable seagrass communities in the region.

The goal of this research is to trace the nutrient inputs from the Piney Point breach to better understand these threats. This objective will be achieved using a novel multi-stable isotope approach to: (1) Characterize the signature of Piney Point effluent; (2) Track the fate of the effluent as it is transported to the nearshore environment; and (3) Evaluate changes in primary producers (phytoplankton communities, macroalgae, and seagrasses) within the region.

The research hypothesis is that discharge from Piney Point will result in a rapid response from phytoplankton and macroalgae, resulting in conditions that may restrict light availability and negatively impact local seagrass communities. The ephemeral nature of this event necessitates quick deployment to obtain samples at the outflow and throughout Tampa Bay.

Successful completion of this research addresses the wider problem of waste discharge from aging and failing infrastructure, a persistent issue throughout the Nation’s coastlines. The results of this research will further benefit society by advancing our understanding of these impacts on fragile coastal ecosystems.

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.