Assessment of present and future nitrogen loads, water quality, and seagrass (Thalassia testudinum) depth distribution in Lemon Bay, Florida
- Cite this article as:
- Tomasko, D.A., Bristol, D.L. & Ott, J.A. Estuaries (2001) 24: 926. doi:10.2307/1353183
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Nitrogen loads into Lemon Bay, Florida were modeled to have increased ca. 59% between pre-development (i.e., 1850) estimates (5.3 kg TN ha−1 yr−1. and estimates for the year 1995 (8.4 kg TN ha−1 yr−1). By the year 2010, nitrogen loads are predicted to increase an additional 45% or 58%, depending upon progress being made toward replacing older septic tank systems with centralized sewerage (nitrogen loads of 12.2 and 13.3 kg TN ha−1 yr−1, respectively). Using 1995 estimates, nonpoint sources (stormwater runoff) are throught to be responsible for ca. 76% of the annual nitrogen load, followed by septic tank systems (14%), rainfall (10%), and an insignificant load from baseflow. Based on an empirically-derived nitrogen load:chlorophylla relationship developed for a portion of nearby Tampa Bay, a 45% increase in nitrogen loads into Lemon Bay could result in a 29% increase in annual average chlorophylla concentrations. Using the estimate of a 29% increase in future chlorophylla concentrations, an empirically-derived optical model for Lemon Bay suggests that light attenuation coefficients in the bay would increase ca. 9%, and the average depth limit ofThalassia testudinum in Lemon Bay would decrease by ca. 24%.