Drivers of Wetland Zooplankton Community Structure in a Rangeland Landscape of the Southern Interior of British Columbia by LINDSEY MARGARET SMITH B.Sc., University of British Columbia, 2005 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN ENVIRONMENTAL SCIENCES in the Department of Natural Resource Sciences Thesis examining committee: Brian Heise (Ph.D.) (Thesis Supervisor), Associate Professor, Natural Resource Sciences, Thompson Rivers University Darryl Carlyle-Moses (Ph.D.), Associate Professor, Geography & Environmental Studies, Thompson Rivers University Lauchlan Fraser (Ph.D.), Professor, Natural Resource Sciences, Thompson Rivers University Louis Gosselin (Ph.D.), Associate Professor, Biological Sciences, Thompson Rivers University Ian Walker (Ph.D.) (External Examiner), Professor, Biology, University of British Columbia-Okanagan May 2012 Thompson Rivers University Lindsey Margaret Smith, 2012 ii Thesis Supervisor: Brian Heise (Ph.D.) ABSTRACT Zooplankton play a vital role in aquatic ecosystems and communities, demonstrating community responses to environmental disturbances. Surrounding land use practices can impact zooplankton communities indirectly through hydrochemistry and physical environmental changes. This study examined the effects of cattle disturbance on zooplankton community structure in wetlands of the Southern Interior of British Columbia. Zooplankton samples were obtained from fifteen morphologically similar freshwater wetlands in the summer of 2009. Physical, chemical and biological characteristics of the wetlands were also assessed. Through the use of Cluster Analysis and Non-metric Multidimensional Scaling (NMDS), differences in community assemblages were found amongst wetlands. Correlations of environmental variables with NMDS axes and multiple regression analyses indicated that both cattle impact (measured by percent of shoreline impacted by cattle) and salinity heavily influenced community structure (species richness and composition). Leptodiaptomus was the dominant copepod genus, Hexarthra and Keratella the dominant rotifer genera, and Ceriodaphnia and Daphnia the dominant cladoceran genera. Species richness decreased with both increasing cattle presence and increasing salinity, with copepods and cladocerans dominating. Least-impacted, least-saline wetlands were characterized by diverse rotifer- dominated assemblages. Impacted wetlands pertained to the highest salinity readings, thus both salinity and cattle impact appeared to have similar confounding effects on community structure. This study supports the use of zooplankton in monitoring programs in B.C. wetlands as there was a significant response to intensifying cattle impact and considerable community differences within small geographical ranges; however, future research is required which examines effects of cattle without confounding results of environmental parameters such as salinity. Keywords: Zooplankton; Wetlands; British Columbia; Cattle; Salinity; Non-Metric Multidimensional Scaling; Land Use; Species Richness; Community Structure iii TABLE OF CONTENTS ABSTRACT ........................................................................................................................................... ii ACKNOWLEDGEMENTS .................................................................................................................. vi LIST OF FIGURES .............................................................................................................................. vii LIST OF TABLES .............................................................................................................................. viii CHAPTER 1 ............................................................................................................................................1 INTRODUCTION ...................................................................................................................................1 Literature Cited ....................................................................................................................................... 9 CHAPTER 2 ..........................................................................................................................................14 Drivers of Wetland Zooplankton Community Structure in a Rangeland Landscape of the Southern Interior of British Columbia ..................................................................................................................14 Introduction .......................................................................................................................................... 14 Study Goals .......................................................................................................................................... 18 Materials and Methods ......................................................................................................................... 18 Site Description .................................................................................................................................... 18 Rose Hill ................................................................................................................................................19 Sampling Design .................................................................................................................................. 20 Cattle Impact Analysis ......................................................................................................................... 20 Sampling – Abiotic Variables .............................................................................................................. 21 Sampling – Biotic Variables ................................................................................................................. 22 Statistical Analysis ............................................................................................................................... 24 Community Structure ........................................................................................................................... 24 Community Change Through Time ...................................................................................................... 25 Environmental Variables Influencing Community Structure ............................................................... 26 Cattle Impact Groups ............................................................................................................................ 27 Results .................................................................................................................................................. 28 iv Wetland Zooplankton Characteristics .................................................................................................. 28 Wetland Hydrochemistry...................................................................................................................... 32 Cattle Impact Assessment..................................................................................................................... 34 Community Structure ........................................................................................................................... 35 Community Structure in Relation to Environmental Variables ............................................................ 39 Community Change Through Time ...................................................................................................... 44 Species Richness and Diversity ............................................................................................................ 44 Abundance ............................................................................................................................................ 47 Biomass ................................................................................................................................................ 48 Chlorophyll-a ........................................................................................................................................ 48 Discussion ............................................................................................................................................ 50 Zooplankton Community Structure in Relation to Cattle Impact ......................................................... 50 Impacted Wetlands ............................................................................................................................... 50 Least-Impacted Wetlands ..................................................................................................................... 51 Zooplankton Community Structure in Relation to Salinity .................................................................. 52 Zooplankton Abundance, Richness and Biomass................................................................................. 54 Abundance ............................................................................................................................................ 54 Species Richness .................................................................................................................................. 55 Biomass ................................................................................................................................................ 57 Conclusion ...........................................................................................................................................