A Fresh Set of Tools: New Information for Managing Fisheries During Changes in River Discharge
USGS scientists are conducting research to understand how estuary fisheries are affected by the the timing and/or magnitude of freshwater discharge into Lake Pontchartrain in Louisiana.
The Science Issue and Relevance: The Bonnet Carré spillway is a well-known flood control structure along the Lower Mississippi River designed to prevent flooding to New Orleans, Louisiana, by diverting excess water from flooding in the watershed into the nearby Lake Pontchartrain estuary. The spillway was opened as much in the most recent decade as the six prior decades combined; the increased freshwater discharge into the estuary was believed to have devastating effects on its recreational and commercial fisheries. The spillway was rarely used historically, therefore there is little science-based guidance for state agencies to consult when managing flooding caused by catastrophic flooding events. The unprecedented uptick in spillway operations calls for dedicated research to understand 1) how the spillway openings affect Lake Pontchartrain estuary fisheries and 2) if the recent increase in spillway operations is expected to continue.
Methodology for Addressing the Issue: This project investigates the fisheries response to Bonnet Carré spillway openings in the context of both physical (i.e., salinity, water temperature) and biological (i.e., nutrient availability, phytoplankton growth) processes. It will also help address how the timing and magnitude of freshwater discharge from the spillway openings affect Lake Pontchartrain fisheries both during and after its operation. This work has three objectives:
1) Estimate the future frequency of spillway operation using global climate model projections;
2) Determine the historical relationship between the timing, intensity, and duration of spillway opening events and subsequent algal biomass; and
3) Assess the historical relationship between phytoplankton biomass and subsequent commercial and recreational fisheries productivity as well as the recovery period.
Future Steps: By achieving the objectives above, this project hopes to address a broader question: How do changes in the timing and/or magnitude of freshwater discharge into an estuary affect its fisheries? This approach can be framed for other productive estuaries in the region of the South Central Climate Adaptation Science Center.
USGS scientists are conducting research to understand how estuary fisheries are affected by the the timing and/or magnitude of freshwater discharge into Lake Pontchartrain in Louisiana.
The Science Issue and Relevance: The Bonnet Carré spillway is a well-known flood control structure along the Lower Mississippi River designed to prevent flooding to New Orleans, Louisiana, by diverting excess water from flooding in the watershed into the nearby Lake Pontchartrain estuary. The spillway was opened as much in the most recent decade as the six prior decades combined; the increased freshwater discharge into the estuary was believed to have devastating effects on its recreational and commercial fisheries. The spillway was rarely used historically, therefore there is little science-based guidance for state agencies to consult when managing flooding caused by catastrophic flooding events. The unprecedented uptick in spillway operations calls for dedicated research to understand 1) how the spillway openings affect Lake Pontchartrain estuary fisheries and 2) if the recent increase in spillway operations is expected to continue.
Methodology for Addressing the Issue: This project investigates the fisheries response to Bonnet Carré spillway openings in the context of both physical (i.e., salinity, water temperature) and biological (i.e., nutrient availability, phytoplankton growth) processes. It will also help address how the timing and magnitude of freshwater discharge from the spillway openings affect Lake Pontchartrain fisheries both during and after its operation. This work has three objectives:
1) Estimate the future frequency of spillway operation using global climate model projections;
2) Determine the historical relationship between the timing, intensity, and duration of spillway opening events and subsequent algal biomass; and
3) Assess the historical relationship between phytoplankton biomass and subsequent commercial and recreational fisheries productivity as well as the recovery period.
Future Steps: By achieving the objectives above, this project hopes to address a broader question: How do changes in the timing and/or magnitude of freshwater discharge into an estuary affect its fisheries? This approach can be framed for other productive estuaries in the region of the South Central Climate Adaptation Science Center.