Clean water is the thread that ties waterfront communities together, drives their economies, and provides a high quality of life for residents and an unforgettable experience for visitors. However, as anthropogenic activities threaten the world’s waterways in multiple ways, harmful algal bloom (HAB) events pose increasing risks. Nutrient pollution from point and nonpoint sources leads to high nutrient loads in waterbodies, leading to eutrophication, and climate change is leading to warmer water temperatures in the ocean and in other waterbodies, raising the prospect for a future where HAB events are more frequent and intense.
This study employs a rich dataset of Karenia brevis (red tide) occurrence and intensity derived from water sampling data in conjunction with Florida Department of Revenue gross sales data in a panel econometric approach to examine the relationship between changes in economic activity and the occurrence and intensity of K. brevis blooms. The analysis focuses on a diverse group of economic sectors belonging to Florida’s tourism economy, including hotels, restaurants, and bars. Gross sales were corrected for inflation using the CPI and converted to million $USD for ease of interpretation. Florida’s state level unemployment rate was included as a control for macroeconomic factors.
Results/Conclusions
During the study period (January 2002 to March 2019), counties along Florida’s Gulf and Atlantic coasts registered at least background concentrations (<1,000 cells/L) of K. brevis on average 19% of months, with one county (Sarasota) registering at least a background concentration 86% of months. Concentrations exceeding 10,000 cells/L begin to cause respiratory irritation and fish kills, and coastal counties registered those concentrations on average 9% of months, with 6 counties in southwest Florida registering them at least 25% of months.
A panel data regression controlling for unobserved differences across counties yields parameter estimates of -2.22 for the red tide abundance indicator (ln of maximum concentration in a given month), -5.61 for Florida unemployment (in percent), and 167.30 for the constant. The regression has an overall R2 of 0.83, indicating a good degree of explanatory power for the variation in gross sales in these sectors. Based on these results, at average monthly maximum concentrations of K. brevis (392,775.18 cells/L) an average county would experience a loss of $28.6 million to its tourism economy.