Storms do not alter long-term watershed development influences on coastal water quality

Area of Science:

• Environmental Science
• Coastal Ecology
• Water Quality Management

Background:

• Coastal lagoons are vital ecosystems susceptible to anthropogenic pressures.
• Understanding the interplay between watershed development and storm events is crucial for effective environmental management.

Purpose of the Study:

• To assess the distinct and combined impacts of watershed development and tropical storms on coastal lagoon water quality.
• To compare the relative influence of urbanization versus storm activity on key water quality parameters.

Main Methods:

• A twelve-year study (2000-2011) of three Gulf of Mexico coastal lagoons with varying urbanization.
• Monitoring of water quality parameters including nitrate, dissolved organic nitrogen, phosphate, chlorophyll a, dissolved oxygen, salinity, and temperature.
• Analysis of data in relation to local watershed development and 22 documented tropical storm events.

Main Results:

• Urbanized lagoons exhibited higher concentrations of nitrate, dissolved organic nitrogen, and phosphate compared to non-urbanized lagoons.
• One urbanized lagoon showed increased chlorophyll a and light extinction, while the non-urbanized lagoon maintained higher dissolved oxygen.
• Storm events caused temporary increases in nitrate, phosphate, and dissolved oxygen, alongside decreases in salinity and temperature, but watershed development exerted a greater long-term influence.

Conclusions:

• Long-term watershed development has a more profound and pervasive impact on coastal lagoon water quality than episodic storm events.
• Environmental management strategies should prioritize mitigating the chronic effects of urbanization to preserve coastal water quality.
• Storm impacts do not fundamentally alter the long-term water quality degradation caused by human watershed development.