Journal of Water Resource and Protection, 2013, 5, 732-742 http://dx.doi.org/10.4236/jwarp.2013.57074 Published Online July 2013 (http://www.scirp.org/journal/jwarp) Changes in Diatom Biodiversity in Lake Sinclair, Baldwin County, Georgia, USA Marká E. Smith * , Kalina M. Manoylov Department of Biological and Environmental Sciences, Georgia College and State University, Milledgeville, USA Email: * marka.smith@tn.gov Received April 29, 2013; revised May 28, 2013; accepted June 22, 2013 Copyright © 2013 Marká E. Smith, Kalina M. Manoylov. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT The effects of increased water temperature on algal community composition were investigated in Lake Sinclair, Bald- win County, Georgia, USA. The lake received waste cooling water from a coal burning power plant. Discharges of re- cycled lake water were, on average, 15˚C ± 1.5˚C (and up to 23˚C) warmer than typical ambient temperatures. Seasonal changes in algal composition were observed, and the warmer sample site had a greater diversity of diatom species year round independent of changes in temperature. Thermal pollution created a high percent dissimilarity between diatoms at the warmer site and the remainder of the lake. Species turnover observed in natural samples was not detected for the warmer site. Anthropogenic thermal pollution was implicated as the factor inducing changes in the natural algal com- munity composition, which may impact other trophic levels and ultimately the overall ecology of Lake Sinclair. Keywords: Diatoms; Heated Water; Southern Lakes; Thermal Pollution 1. Introduction Thermal pollution is the degradation of water quality by any process that changes the ambient water temperature. Persistent differences in ambient water temperature may result in eutrophication, loss of ecosystem processes such as biological productivity and lake metabolism, con- taminant toxicity, and loss of aquatic biodiversity [1]. It has been reported that cooling systems from coal burning power plants have no harmful effects on a system as a whole [2]. However, effects of thermal pollution in aqua- tic systems are greatly influenced by industry, agriculture, and urban habitats [1,3-9]. Effect of thermal pollution on algae has not been addressed in Georgia, but in a sou- thwestern lake thermal loading depressed primary pro- duction of phytoplankton [10]. Lake Sinclair, in Central Georgia, is a manmade lake owned by Georgia Power. Water from the lake is used to cool the turbines of a coal burning Power plant. About a billion gallons of water per day is extracted from the lake, and when pumped back into the lake it is intended to be within a few degrees of the ambient temperature [11]. The effects of thermal pollution have been documented previously [12], and it was reported that approximately 3% of the lake was di- rectly impacted by water that was too warm when it was released. Cooling towers are supposed to decrease water tem- perature to ambient temperatures before being released, reducing the impact of thermal pollution on the sur- rounding system [13]. In 2002, Georgia Power finished installing a cooling tower to comply with Georgia Envi- ronmental Protection Division’s (GA EPD) [14] regula- tion to control effluent water temperature. The other condition required for compliance is that at no time is the temperature of the receiving waters to be increased by more than 15˚C above intake temperature or the lake’s natural temperature gradient. The installation was done in response to a number of fish kills in the 1990’s in Beaverdam Creek [15]. Past research on Lake Sinclair is limited, with little to no research on potential thermal pollution and its effects on primary producers. The State of Georgia has continuously monitored temperature data from DNR/EPD/Watershed Protection Branch since 2009. Three sites that the State monitored on Lake Sinclair provided additional temperature information in this study for the baseline conditions within the lake. Diatoms (Bacillariophyta) are often reported as the dominant group in lake communities [16] and are known to show definitive responses to different stressors and environmental conditions [17-21]. Their rapid cell cycles have been used to infer changes in composition due to * Corresponding author. Copyright © 2013 SciRes. JWARP