FISHES OF SAVANNAS PRESERVE STATE PARK by Kristy McKee A Thesis Submitted to the Faculty of The Wilkes Honors College in Partial Fulfillment of the Requirements for the Degree of Bachelor of Arts in Liberal Arts and Sciences with a Concentration in Marine Biology Wilkes Honors College of Florida Atlantic University Jupiter, Florida August 2007 FISHES OF SAVANNAS PRESERVE STATE PARK by Kristy McKee This thesis was prepared under the direction of the candidate’s thesis advisor, Dr. Jon Moore, and has been approved by the members of her/his supervisory committee. It was submitted to the faculty of The Honors College and was accepted in partial fulfillment of the requirements for the degree of Bachelor of Arts in Liberal Arts and Sciences. SUPERVISORY COMMITTEE: ____________________________ Dr. Jon Moore ____________________________ Dr. William O’Brien ______________________________ Dean, Wilkes Honors College ____________ Date ii Acknowledgements I would like to thank Dr. Jon Moore, Andrea Gagaoudakis, Janny Peña, Kelley McKee, Scott Moore, Carrie Goethel, Diego Arenas, Tony Uhl, Leslie Jacobson, and the Port St. Lucie High School Science Club members for their assistance in the field and in the laboratory; Kasey McKee for helping making the map; Dr. Jon Moore and Dr. William O’Brien for their helpful comments and suggestions during the writing process; Hank Smith for allowing me to embark on this project, assistance with acquiring permits, past collecting information, and general information about Savannas Preserve State Park; Greg Kaufman and Savannas Preserve State Park for passing on information about exotics collected in the park; and the Florida Museum of Natural History and Harbor Branch Oceanographic Institution for preserved specimens and catalog information from past collections. I would also like to thank Dr. Jon Moore and Hank Smith for encouraging me to work in a freshwater habitat. Additionally, I would like to thank the professors at the Harriet L. Wilkes Honors College and Harbor Branch Oceanographic Institution for preparing me for this project. Lastly, I would like to thank my family and friends for supporting me throughout this process. iii ABSTRACT Author: Kristy McKee Title: Fishes of Savannas Preserve State Park Institution: Wilkes Honors College of Florida Atlantic University Thesis Advisor: Dr. Jon Moore Degree: Bachelor of Arts in Liberal Arts and Sciences Concentration: Marine Biology Year: 2007 Freshwater marshes are a harsh wetland ecosystem classified by seasonal water level fluctuation. Dry down periods are common in some marshes, making life difficult for fish and other aquatic organisms. The goal of this study was to compile an updated species list of fishes inhabiting the freshwater marsh system within Savannas Preserve State Park. Twenty-three fish species were collected between August 2005 and May 2007. This survey, along with past collections, and the current species list in the park’s management plan were used to make a new proposed species list. Three species of nonnative fishes were observed during the study, the first report of exotic fishes in the park. It is believed that abnormally high water levels for an extended period may have allowed the water in neighboring canals to connect to the marsh system and, as a result, new species were able become introduced in the park. iv Table of Contents List of Tables ………………………………………………………………………vi List of Figures ……………………………………………………………………..vii Introduction ………………………………………………………………………... 1 Materials and Methods ……………………………………………………………. 2 Study Area ………………………………………………………………… 2 Previous Collections……………………………………………………….. 4 Current Study Collection ………………………………………………….. 5 Results ……………………………………………………………………………... 6 Discussion………………………………………………………………………….. 7 Tables………………………………….…………………………………………..13 Figures..…………………………………………………………………………....22 Field Notes…………………………………………………………………………23 References………………………………………………………………………….27 v List of Tables Table A. Harrington Collection 1955……………………………………………… 13 Table B. Smith and Miller Collection 1994………………………………………... 14 Table C. Miller Collection 1995…………………………………………………… 15 Table D. Current Species List from the 2003 Management Plan (FDEP 2003)…… 16 Table E. Current Study Collection…………………………………………………. 17 Table F. Proposed Species List…………………………………………………….. 18 Table G. Comparison of Species Lists……………………………………………... 19 Table H. Current Study Collection Site Number and Method Used………………. 20 vi List of Figures Figure 1. Map of Savannas Preserve State Park and surrounding areas…………… 22 vii Introduction Wetlands make up a large portion of Florida’s environment. Of these wetlands, one-third is composed of freshwater marshes (Hefner 1986) with the Everglades representing the largest expanse of a freshwater marsh system in the state (Kushlan 1990). One of the most notable characteristics of a freshwater marsh in Florida is the seasonal fluctuation of water levels. In some areas, rainfall and evaporation are the major factors in determining surface water levels. Consequently, Florida’s dry season often results in dry outs in much of the marsh habitat; however, the marsh may become fully inundated with water in the following wet season (Kushlan 1990). In order to survive, marsh inhabitants must be able to adapt to the changing water levels (Kushlan 1976). When water levels drop, the fishes and other aquatic organisms are confined to depressions where the animals are then at higher risk of predation and the possibility of low oxygen (Kushlan 1990). The purpose of this study is to survey the ichthyofauna of the freshwater marsh system in Savannas Preserve State Park located in southeastern Florida. Previous fish collections have been conducted in the park by three groups; however, the collections did not encompass a large portion of the wetlands. Results from the previous studies are utilized in this study in order to observe possible changes in the fish fauna at Savannas Preserve. Prior to the current study, southern Florida experienced two successive years of very active hurricane seasons (2004 and 2005). During this time, the high level of precipitation caused unusually high water levels within the park that were maintained for a long period. This study will aid in giving insight into the effects of a very active wet season in the Savannas Preserve marsh system. The information from this study along 1 with information collected from previous studies in the park and the park’s management plan will be used to compile a proposed species list. Materials and Methods Study Area Savannas Preserve State Park extends from Jensen Beach Boulevard in Jensen Beach, Florida north to East Midway Road in Port St. Lucie, Florida (Figure 1). Although the park includes seven different natural communities, as defined by the Florida Department of Natural Resources, freshwater wetlands make up 45% of the land area in the park (FDEP 2003). The wetlands form a 700-hectare, north-south corridor on the western side of the Atlantic Coastal Ridge (Graves et al. 1998). Oligotrophic basin marshes, depression marshes, wet prairies, and marsh lakes comprise the wetlands found within the park (FDEP 2003). Due to the topography of the area, many of these wetlands are controlled primarily by precipitation (FDEP 2003). One thing that makes this park unique is the relative isolation of the freshwater marshes. Under normal circumstances, the marshes fill exclusively from rainfall within the park itself and any excess water flows out of the park via two small canals. Bordering the park there are two residential areas, and when unusually heavy rain has fallen, the flow in those two canals can reverse so that water from these residential areas can enter the park (Graves et al. 1998). Similar to other marsh habitats, during periods of low rainfall the aquatic animals in the park are forced to inhabit deeper areas including alligator ponds, marsh lakes, and human-made dredged areas (Smith pers. comm. 2006, not referenced). During periods of severe drought, large fish kills commonly occur (Kushlan 1974a in Loftus and Kushlan 2 1987). Because the main source of water in Savannas Preserve is rainfall within the park, the natural condition of the water is acidic (with pH values as low as 4.3) due to the decomposition of plant matter within the marsh system (Graves et al. 1998). The acidic condition of the water may also have an effect on which fish species are able to live within the park. Starting in late 2004 and continuing to 2007, the highly variable rainfall in the region featured several unusually extreme events of heavy rainfall followed by severe drought. In September 2004, two powerful hurricanes, Frances and Jeanne, hit Savannas Preserve State Park. The precipitation from these storms caused the water levels to become persistently very high within the marsh. In October 2005, Savannas was hit again from the west by hurricane Wilma. This storm allowed for the high water levels in the park to remain for an extended period. By November 2005, water levels were still up to 1 m above normal. Normal marsh water levels were not achieved until March 2006. The spring and summer of 2006 brought lower than average rainfall, especially when compared to the two previous years; consequently, water levels began to drop by May and much of the marsh was dried out by October 2006. The dry out did not last long because the El Niño –Southern Oscillation began to show an effect in the fall and winter. During El Niño events, Florida experiences an unusually high amount of rainfall