OPEN ACCESS International Journal of Aquatic Science ISSN: 2008-8019 Vol. 6, No. 2, 3-10, 2015 () hanifeozbay@gmail.com The effects of bird exclusion on the chemical and biological characteristics of a soda lake Hanife Özbay Department of Biology, Faculty of Sciences, Nevsehir University, 50300, Nevsehir, Turkey Received: 02 December 2014 Accepted: 29 December 2014 Published: 06 June 2015 Abstract: The effects of water birds on water quality in a shallow Turkish soda lake, Lake Aktaş, were investigated by comparing protected areas and those exposed to birds, in order to understand interactions between the birds and the ecosystem in this study. The experiment was carried out over five months between June and October 2009, in four widely distributed bird-proof enclosures in treatment areas and four open-top enclosures (control areas), a total of eight plots, (with a fish density of about 1000 kg.ha -1 , similar to the lake) in the lake. Physico- chemical analyses, phytoplankton, zooplankton, Secchi depth measurements, were determined each month in both treatment and control areas. The significant differences were found only for chlorophyll a (P<0.001) and Secchi depth (P<0.05) throughout the experiment between the open and bird-proof enclosures. Although some effects of water birds were clear in the present study such as decrease in turbidity and chlorophyll a, it is difficult to determine the effect of waterfowl on water chemistry using enclosure experiments, since they are designed to test the effect of ornithogenic inputs on the water column, not the effects of other factors (e.g. natural chemistry). Key Words: waterfowl, water quality, aquatic ecosystem, ornithogenic input, nutrients Introduction Waterfowl such as geese, swans, wild ducks, and others are natural components of shallow lake ecosystems that can have important effects on both the biology and chemistry of these ecosystems. The majority of research on the observable effects of birds on aquatic systems (Manny et al., 1975, 1994; Scherer et al., 1995; Kear, 1963; Olson, 2005; Post et al., 1998; Kitchell et al., 1999) has been performed in large lakes and bays, and these studies have indicated that goose faeces impact water quality. Although the effects of waterfowl on water quality have been much studied (Gould and Fletcher, 1978; Bedard and Gauthier, 1986; Portnoy, 1990; Bales et al., 1993; Dobrowolski et al., 1993; Baxter and Fairweather, 1994; Manny et al., 1994; Marion et al., 1994; Smith and Johnson, 1995; Gwiazda, 1996; Kitchell, et