Old Dominion University ODU Digital Commons Biological Sciences Theses & Dissertations Biological Sciences Spring 2013 Investigations of Phytoplankton Diversity in Chesapeake Bay Todd Arthur Egerton Old Dominion University Follow this and additional works at: https://digitalcommons.odu.edu/biology_etds Part of the Biodiversity Commons, Ecology and Evolutionary Biology Commons, and the Environmental Monitoring Commons Recommended Citation Egerton, Todd A.. "Investigations of Phytoplankton Diversity in Chesapeake Bay" (2013). Doctor of Philosophy (PhD), dissertation, Biological Sciences, Old Dominion University, DOI: 10.25777/mzhb-5644 https://digitalcommons.odu.edu/biology_etds/85 This Dissertation is brought to you for free and open access by the Biological Sciences at ODU Digital Commons. It has been accepted for inclusion in Biological Sciences Theses & Dissertations by an authorized administrator of ODU Digital Commons. For more information, please contact [email protected]. INVESTIGATIONS OF PHYTOPLANKTON DIVERSITY IN CHESAPEAKE BAY by Todd Arthur Egerton B.S. May 2001, Susquehanna University M.S. May 2005, Old Dominion University A Thesis Submitted to the Faculty of Old Dominion University in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY ECOLOGICAL SCIENCE OLD DOMINION UNIVERSITY May, 2013 Approved by: Harold G. Marshall (Director) DamferM. Dauer (Member) R. Mulholland (Member) Kneeland K. Nesius (Member) ABSTRACT INVESTIGATIONS OF PHYTOPLANKTON DIVERSITY IN CHESAPEAKE BAY Todd Arthur Egerton Old Dominion University, 2013 Director: Dr. Harold G. Marshall Characterizing the diversity of a community in relation to environmental conditions and ecosystem functions are core concepts in ecology. While decades of research have led to a growing comprehension of diversity in many ecosystems, our understanding in aquatic habitats and microbial organisms remains relatively limited. Phytoplankton represent a diverse and important group that contribute approximately half of global primary productivity and are intrinsically connected to changing environmental conditions, especially in systems as dynamic as estuaries. To better understand the ecological processes governing phytoplankton composition and diversity, spatial and temporal patterns of environmental parameters and their relation to the algal community of Chesapeake Bay were analyzed using data collected over a 25 year period (1985- 2009). The phytoplankton community of Chesapeake Bay, containing 1480 taxa was characterized as one of high richness and low evenness, with a single species accounting for at least half of the biomass in almost one third of all samples examined. High gamma-diversity was attributed to seasonal succession of dominant flora and spatial heterogeneity along the estuarine gradient with high species turnover between salinity regions. Alpha-diversity was greatest in freshwater and polyhaline regions, and minimal in lower mesohaline waters. Multivariate ordination analysis identified regional differences corresponded to salinity, turbidity, and nutrient gradients, with lowest richness in regions of intermediate salinity, total nitrogen and phosphorus concentrations and highest dissolved organic nitrogen. Temporal factors included negative impacts of streamflow related nutrient increases leading to greater algal abundance and lower diversity particularly within the polyhaline Bay. Results indicate that greater algal biomass was associated with higher richness and lower evenness, and may be associated with lower ecosystem stability, with greater variance in inter-annual phytoplankton biomass. To address short-term environmental variability including nutrient loading, daily sampling of the Lafayette River, was conducted in spring 2006. During consecutive blooms of Cryptomonas sp. and Gymnodinium instriatum up to 99% of total biomass was due to the individual bloom species, although species richness was not significantly reduced. Time lag correlations indicated that the Cryptomonas sp. bloom was related to precipitation related increases in dissolved inorganic nitrogen concentrations, while the G. instriatum bloom followed periods of reduced nitrogen concentrations that were accompanied by an algal community of high richness and low evenness. Based on its connectivity to both environmental and biological variables, phytoplankton diversity is recognized as a significant indicator of ecosystem condition, with high species richness and evenness as potential goals for restoration efforts. This thesis is dedicated to my family Jessica, Evan and Anna Egerton. ACKNOWLEDGMENTS This project would not be possible without the help o f a large number o f people whom I’d like to acknowledge. I consider Dr. Harold Marshall an academic advisor, mentor, professional collaborator and friend. His expertise of phytoplankton taxonomy is world renowned, and eclipsed only by his continued dedication to his students and his curiosity and passion for research. This dissertation builds on the long tradition o f research within Chesapeake Bay, including a legacy of work coming out of the Phytoplankton Analysis Laboratory at Old Dominion University. I would like to thank the dozens o f graduate research assistants past and present that have worked in the phytolab, without whom, these analyses wouldn’t have been possible. A special appreciation is extended to Matthew Semcheski and Matthew Muller, who in addition to their worked in the lab for several years, have helped shape the analyses and research questions posed in this dissertation through countless hours o f discussion and debate. Additional members o f the Chesapeake Bay monitoring program include Suzanne Doughten and Mike Lane who provided assistance with water quality data and statistical analysis. Ryan Morse, Katherine Filippino, and Peter Bernhardt also helped regarding nutrient data and research within the Lafayette River. I would also like to thank the rest o f my research committee, Drs. Margaret Mulholland, Daniel Dauer, and Kneeland Nesius for their assistance in developing the project and editing the manuscript. This project came out o f initial discussions with Dr. Christopher Binckley, who introduced me to the interactions between biodiversity and ecosystem function. Finally I’d like to thank friends and family for their help during my tenure as a doctoral student, especially my wife Jessica for her patience and support. I’d like to acknowledge the Virginia Department o f Environmental Quality, Virginia Department o f Health, Chesapeake Bay Program, and Virginia Coastal Energy Research Consortium for funding support. TABLE OF CONTENTS Page LIST OF TABLES.......................................................................................................................ix LIST OF FIGURES......................................................................................................................x INTRODUCTION TO BIODIVERSITY AND CHESAPEAKE BAY.................................1 SPATIAL PATTERNS OF PHYTOPLANKTON DIVERSITY AND COMPOSITION IN CHESAPEAKE BAY ............................................................................ 13 INTRODUCTION......................................................................................................... 13 METHODS..................................................................................................................... 19 RESULTS....................................................................................................................... 24 DISCUSSION.................................................................................................................46 CONCLUSIONS........................................................................................................... 52 SEASONAL PATTERNS OF WATER QUALITY, PHYTOPLANKTON ABUNDANCE, COMPOSITION AND DIVERSITY AND THE EFFECTS OF STREAMFLOW IN CHESAPEAKE BAY.............................................................................54 INTRODUCTION.........................................................................................................54 METHODS.....................................................................................................................58 RESULTS.......................................................................................................................61 DISCUSSION.................................................................................................................83 CONCLUSIONS........................................................................................................... 89 PHYTOPLANKTON DIVERSITY AND ECOSYSTEM FUNCTIONS IN A EUTROPHIC ESTUARY; PRODUCTIVITY, STABILITY AND TROPHIC INTERACTIONS.......................................................................................................................90 INTRODUCTION.........................................................................................................90 METHODS.....................................................................................................................93 RESULTS.......................................................................................................................94 DISCUSSION................................................................................................................ 99 CONCLUSIONS......................................................................................................... 110 ALGAL BLOOMS: CASE STUDIES IN PHYTOPLANKTON DRIVERS