The Effect of Nutrient Enrichment on Stream Periphyton Growth In
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THE EFFECT OF NUTRIENT ENRICHMENT ON STREAM PERIPHYTON GROWTH IN THE SOUTHERN COASTAL PLAIN OF GEORGIA: IMPLICATIONS FOR LOW DISSOLVED OXYGEN by RICHARD CAREY (Under the Direction of Catherine Pringle and George Vellidis) ABSTRACT Blackwater rivers are common throughout the Atlantic Coastal Plain and water quality is heavily influenced by the flat topography, sandy soils and floodplain swamp forests. In the southern coastal plain of Georgia, streams regularly violate dissolved oxygen (DO) standards established by the Georgia Department of Natural Resources. Total Maximum Daily Load (TMDL) management plans must be developed for watersheds that are drained by DO-impaired streams but previous studies suggest DO may be naturally low. At nine sites throughout the region, eighteen passive nutrient diffusion periphytometers were deployed to determine if algal growth was nutrient and/or light limited. Periphyton biomass for treatments in the sun, measured as chlorophyll a, was significantly (p < 0.05) greater than corresponding treatments in the shade and algal growth was nutrient-limited at several sites where DO concentrations were below regulatory standards. Factors other than algae may be responsible for low DO concentrations during summer. INDEX WORDS: Periphyton, Periphytometer, Dissolved Oxygen, Nutrient Enrichment THE EFFECT OF NUTRIENT ENRICHMENT ON STREAM PERIPHYTON GROWTH IN THE SOUTHERN COASTAL PLAIN OF GEORGIA: IMPLICATIONS FOR LOW DISSOLVED OXYGEN by RICHARD CAREY B.S., University of Miami, 2001 A Thesis Submitted to the Graduate Faculty of The University of Georgia in Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE ATHENS, GEORGIA 2005 © 2005 Richard Carey All Rights Reserved THE EFFECT OF NUTRIENT ENRICHMENT ON STREAM PERIPHYTON GROWTH IN THE SOUTHERN COASTAL PLAIN OF GEORGIA: IMPLICATIONS FOR LOW DISSOLVED OXYGEN by RICHARD CAREY Major Professors: Catherine Pringle George Vellidis Committee: Richard Lowrance Matt Smith Electronic Version Approved: Maureen Grasso Dean of the Graduate School The University of Georgia May 2005 iv DEDICATION For my mother, who encouraged her children to aim and achieve. v ACKNOWLEDGEMENTS I would like to thank my committee, Catherine Pringle, George Vellidis, Richard Lowrance, and Matt Smith for their insight and guidance as I refined my experimental approach and completed my thesis. I am also grateful to Paige Gay, Wynn Bloodworth and Debbie Coker at NESPAL and Chris Clegg, Leila Hargett and Cagney Parker at USDA-SEWRL for their help with various laboratory analyses in Tifton, GA. Thanks to Andy Knowlton and Rodney Hill who helped with construction, deployment and retrieval of periphytometers. I would also like to thank Stephen Golladay and his lab for their support during experiments at the Jones Ecological Research Center. At the Institute of Ecology, special thanks to both Rhema Bjorkland and Patsy Pittman for their help throughout my graduate program. vi TABLE OF CONTENTS Page ACKNOWLEDGEMENTS.............................................................................................................v LIST OF TABLES....................................................................................................................... viii LIST OF FIGURES ....................................................................................................................... ix CHAPTER 1 INTRODUCTION .........................................................................................................1 Background ...............................................................................................................1 303(d) Lists................................................................................................................2 Factors Affecting Dissolved Oxygen ........................................................................2 Objectives..................................................................................................................3 2 LITERATURE REVIEW..............................................................................................6 Background ...............................................................................................................6 Nutrient Limitation and Biogeochemical Cycles ......................................................7 Bio-available forms of Nitrogen and Phosphorus .....................................................9 Nutrient Enrichment Studies ...................................................................................10 Dissolved Oxygen ...................................................................................................11 Hypoxia in the Chesapeake Bay and the Gulf of Mexico .......................................12 Coastal Plain Streams..............................................................................................14 Water Quality Implications .....................................................................................16 3 PRELIMINARY EXPERIMENTS..............................................................................20 vii Passive Nutrient Diffusion Periphytometers ...........................................................20 Diffusion Rate .........................................................................................................31 4 PERIPHYTON RESPONSE TO NUTRIENT ENRICHMENT: METHODS............58 Introduction .............................................................................................................58 Study Sites...............................................................................................................58 Physicochemical Analyses ......................................................................................64 Chlorophyll a Analyses...........................................................................................65 Statistical Analyses..................................................................................................65 5 RESULTS ....................................................................................................................83 Physicochemical Analyses ......................................................................................83 Chlorophyll a Analyses...........................................................................................86 6 DISCUSSION............................................................................................................106 Factors Affecting Relative Periphyton Growth.....................................................106 7 CONCLUSIONS........................................................................................................120 Georgia Coastal Plain Streams: Algae and Dissolved Oxygen.............................120 Study Limitations ..................................................................................................121 Recommendations for Future Research ................................................................122 REFERENCES ............................................................................................................................124 APPENDICES .............................................................................................................................130 A CHLOROPHYLL A DATA FOR PRELIMINARY EXPERIMENTS.....................130 B FLOW DATA............................................................................................................155 C RESIDUAL NUTRIENT CONCENTRATIONS......................................................157 D CHLOROPHYLL A DATA......................................................................................176 viii LIST OF TABLES Page Table 3.1: Summary chlorophyll a data for preliminary periphytometer experiments .................36 Table 3.2: Stream nutrient concentrations during preliminary periphytometer experiments ........38 Table 3.3: Residual concentrations in nitrate-phosphate nutrient reservoirs after preliminary periphytometer experiments..........................................................................................39 Table 3.4: Ten-day diffusion experiment data...............................................................................42 Table 3.5: Fifteen-day diffusion experiment data..........................................................................43 Table 4.1: Watershed data for the nine study sites ........................................................................68 Table 5.1: Stream variables on periphytometer deployment and retrieval dates...........................90 Table 5.2: Irradiance measurements at the nine study sites...........................................................92 Table 5.3: Stream molar N: P ratios on periphytometer deployment and retrieval dates..............93 Table 5.4: Relative flow on periphytometer deployment and retrieval dates................................94 Table 5.5: Average chlorophyll a values and residual nutrient concentrations in the shade.........95 Table 5.6: Average chlorophyll a values and residual nutrient concentrations in the sun ............96 Table 5.7: Summary chlorophyll a data for periphytometers deployed in the shade ....................97 Table 5.8: Summary chlorophyll a data for periphytometers deployed in the sun........................98 Table 6.1: Limiting nutrients for algal growth at the nine study sites .........................................118 Table 6.2: Nutrient concentrations and mean daily flow before and after experiments in the Little