W&M ScholarWorks Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects 2009 Multi-system analysis of nitrogen use by phytoplankton and heterotrophic bacteria Paul B. Bradley College of William and Mary - Virginia Institute of Marine Science Follow this and additional works at: https://scholarworks.wm.edu/etd Part of the Biogeochemistry Commons, and the Marine Biology Commons Recommended Citation Bradley, Paul B., "Multi-system analysis of nitrogen use by phytoplankton and heterotrophic bacteria" (2009). Dissertations, Theses, and Masters Projects. Paper 1539616580. https://dx.doi.org/doi:10.25773/v5-8hgt-2180 This Dissertation is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Dissertations, Theses, and Masters Projects by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. Multi-System Analysis of Nitrogen Use by Phytoplankton and Heterotrophic Bacteria A Dissertation Presented to The Faculty of the School of Marine Science The College of William and Mary in Virginia In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy by Paul B Bradley 2008 APPROVAL SHEET This dissertation is submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy r-/~p~J~ "--\ Paul B Bradle~ Approved, August 2008 eborah A. Bronk, Ph. Committee Chair/Advisor ~vVV Hugh W. Ducklow, Ph.D. ~gc~ Iris . Anderson, Ph.D. Lisa~~but Campbell, P . Department of Oceanography Texas A&M University College Station, Texas 11 DEDICATION Ami querida esposa, Silvia, por tu amor, apoyo, y paciencia durante esta aventura que has compartido conmigo, y A mi hijo, Dominic, por tu sonrisa y tus carcajadas, que pueden alegrar hasta el mas melanc61ico de los dias 111 TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ........................................................................ v LIST OF TABLES ................................................................................... vi LIST OF FIGURES ................................................................................ vii ABSTRACT ........................................................................................ viii CHAPTER 1 .......................................................................................... 2 Introduction CHAPTER 2 ........................................................................................ 36 Phytoplankton and bacterial nitrogen use in Chesapeake Bay measured using a flow cytometric sorting approach CHAPTER 3 ........................................................................................ 77 Influence of summer stratification on phytoplankton nitrogen uptake in a Mid-Atlantic Bight upwelling region CHAPTER 4 ...................................................................................... 123 Nitrogen use by phytoplankton and bacteria during an induced Phaeocystis pouchetii bloom, measured using size fractionation and flow cytometric sorting approaches CHAPTER 5 ...................................................................................... 168 Cross-system comparison of phytoplankton and bacterial nitrogen uptake measured using flow cytometric sorting versus traditional filtration CHAPTER 6 ...................................................................................... 212 Conclusion VITA ............................................................................................... 227 iv ACKNOWLEDGEMENTS I greatly appreciate the energy and enthusiasm Debbie Bronk has devoted to serving as my mentor these past years, and I sincerely thank her for the opportunities I have been afforded during this time. She has lended an experienced eye and fresh outlook on my work countless times, and her quick but thoughtful comments on earlier drafts of this dissertation have helped immensely. I thank my committee members, Hugh Ducklow, Iris Anderson, Debbie Steinberg, and Lisa Campbell, for their help and guidance not just in completing this dissertation and improving manuscripts, but in all aspects of my graduate education. Marta Sanderson, my "junior advisor", has helped with everything from nutrient analyses to running the mass spec (always an adventure!), has offered valuable input on papers and presentations, has worked tirelessly with me in the field and lab, and all while being a great friend. K.C. Filippino, Quinn Roberts, Jason See, Rob Condon, and other occupants of the Bronk Lab have assisted with nutrient analyses and provided thoughtful discussion. I am especially grateful to Lynn Killberg for her help processing samples on the mass spec, and to Helen Quinby for helping me figure out what a flow cytometer is. I deeply appreciate all the laughs and moral support that my VIMS friends have given me. I thank the captains, crews, and colleagues who have made my efforts on research cruises possible, and particularly those who have shared their own data from these projects. The administrative expertise of Sue Presson, Katherine Davis-Small, Cindy Hornsby, Cynthia Harris, and Fonda Powell has made my life immeasurably easier. I am also grateful to the U.S. Environmental Protection Agency Science to Achieve Results (STAR) Graduate Fellowship Program for supporting this work. My parents, Robert and Marsha Burt, nourished my intellectual development, and together with my sister, Alicia, and brother, Tom, have given me endless encouragement. None of this would have been possible without the love and support of my wife, Silvia ... it has been a long, arduous journey, but we've successfully reached the finish line (and sprinting too!). And with little effort, my son, Dominic, has given more meaning, perspective, and joy to life in one brief year than I could have ever hoped for. v LIST OF TABLES Page CHAPTER 1 Table 1 Literature values ofbacterial retention on GF/F filters ooooooooooooooooo 000 34 CHAPTER2 Table 1 Overestimation of phytoplankton N uptake by GF IF filters 0000 00 0 0 0 0 0 0 69 CHAPTER3 Table 1 Particulate Nand specific N uptake: GF/F vso >008 )lm 00000000000000000 113 Table 2 Relative importance ofN substrates: GF/F vso >5/3 )lm 0000000000000000 114 Table 3 Relative importance ofN substrates: GF/F, >5/3 )lm, FCM 0000 000000 115 CHAPTER4 Table 1 Absolute N uptake rates: >008 )lm vso Phyto ooooooooooooooooooooooooooo 00 0 0 0 0 157 Table 2 Contribution of 15N substrates to total N uptake 000000000000000000000 00 0 0 0 0 158 CHAPTERS Table 1 Literature values ofbacterial retention on GF/F filters 0000000000000000000 201 Table 2 Summary of sampling design by ecosystem ooooooooooooooooooooooooooo 00 0 oooo 202 Table 3 Chlorophyll a retention on 002 )lm Supor filters 000000000000000000000 00 0 0000 203 Table 4 Composition ofTDN pool by ecosystem 000000000000000000000000000000000000000 204 Table 5 Contribution of 15N substrates to total N uptake 0000 00000000000000000 00 0 000 0 205 Table 6 Relative importance ofN substrates: High vso Low N input 0000000000 206 Vl LIST OF FIGURES Page CHAPTER 1 Figure 1 Microbial marine N cycle ............................................................... 35 CHAPTER2 Figure 1 Chesapeake Bay station map .......................................................... 70 Figure 2 Dissolved N concentrations ............................................................ 71 Figure 3 Particulate N concentrations ........................................................... 72 Figure 4 Specific N uptake rates ................................................................... 73 Figure 5 Absolute N uptake rates ................................................................. 74 Figure 6 Contribution of 15N substrates to total N uptake ............................ 75 Figure 7 Correlation between DON:DIN and DF AA uptake rates .................. 76 CHAPTER3 Figure 1 Dissolved N concentrations at LE0-15 ....................................... 116 Figure 2 Percent contribution ofN to TDN pool and to GF/F uptake .......... 117 Figure 3 Particulate N concentrations at LE0-15 ......... ....... .................. ..... 118 Figure 4 Absolute N uptake by the GF/F fraction ....................................... 119 Figure 5 Absolute N uptake by the >5 and >3 Jlm fractions ......................... 120 Figure 6 Specific N uptake rates at LE0-15 ......................... ...................... 121 Figure 7 Phylogenetic relationships inferred from ureC analysis ................. 122 CHAPTER4 Figure 1 Chlorophyll a and particulate N concentrations . .. ... ........ .... ....... 159 Figure 2 Plankton community composition ..................... .......................... 160 Figure 3 Dissolved N concentrations .................... ....... .............................. 161 Figure 4 Percent composition of TDN pool ......................... ...................... .. 162 Figure 5 Concentrations of DOC, phosphate, and silicate .. ..... ................. 163 Figure 6 Rates of ammonium regeneration ...... ........................... ............... 164 Figure 7 Specific N uptake rates . ................... ...................... .... ............ ........ 165 Figure 8 Absolute N uptake by phytoplankton and bacteria ... ........ ....... .. 166 Figure 9 Contribution of 15N substrates to total N uptake ........................... 167 CHAPTERS Figure 1 TDN concentrations and NH/ regeneration rates . .............. ......... 207 Figure 2 Filter-based vs. FCM uptake of ammonium and nitrate ........ ........ 208 Figure