DELAWARE NATIONAL ESTUARINE RESEARCH RESERVE ESTUARINE PROFILE Prepared by Delaware Department of Natural Resources and Environmental Control Delaware National Estuarine Research Reserve 818 Kitts Hummock Rd. Dover, DE 19901 June, 1999 Publication of this document made possible by grants NA77ORO506 and NA47ORO369 from NOAA’s Office of Ocean and Coastal Resource Management. TABLE OF CONTENTS TABLE OF CONTENTS.............................................................................................................................................i TABLE OF FIGURES ...............................................................................................................................................iii TABLE OF TABLES..................................................................................................................................................v ACKNOWLEDGMENTS...........................................................................................................................................1 PREFACE....................................................................................................................................................................3 SITE PROFILE OVERVIEW....................................................................................................................................4 COMPREHENSIVE SITE PROFILE ....................................................................................................................23 INTRODUCTION TO THE RESERVE..........................................................................................................................23 GEOGRAPHIC SETTING...........................................................................................................................................29 Geography and Biogeography ............................................................................................................................29 Boundaries and Ownership of Reserve Sites.......................................................................................................29 Upper Blackbird Creek Reserve ........................................................................................................................................ 29 Lower St. Jones River Reserve .......................................................................................................................................... 30 Human population...............................................................................................................................................31 ENVIRONMENTAL SETTING....................................................................................................................................31 Geology ...............................................................................................................................................................31 Hydrogeology......................................................................................................................................................32 Estuarine Geomorphology ..................................................................................................................................32 Topography .........................................................................................................................................................33 Climate ................................................................................................................................................................33 Soils.....................................................................................................................................................................35 Tidal Hydrography (main channels) ...................................................................................................................35 Tide ranges ........................................................................................................................................................................ 39 Tide wave progression....................................................................................................................................................... 39 Tide wave lags................................................................................................................................................................... 40 Channel widths and depths ................................................................................................................................................ 40 Tidal current velocities ...................................................................................................................................................... 47 Future Tidal Hydrography Information ............................................................................................................................. 47 Surface water quality (main channel tidal waters)..............................................................................................52 Water temperature ............................................................................................................................................................. 52 Turbidity............................................................................................................................................................................ 55 pH...................................................................................................................................................................................... 55 Dissolved Oxygen.............................................................................................................................................................. 55 Salinity............................................................................................................................................................................... 55 Dissolved Nutrients, BOD and Chlorophyll-a/Pheophytin-a ............................................................................................. 69 Watershed Land Use Cover.................................................................................................................................69 ECOLOGICAL/BIOLOGICAL SETTING ....................................................................................................................74 Reserve Vegetation..............................................................................................................................................74 Tidal datums and coastal marsh vegetation zonation......................................................................................................... 74 Dominant vegetation cover................................................................................................................................................ 74 Emergent wetlands vegetation ........................................................................................................................................... 77 Forest vegetation................................................................................................................................................................ 83 Expansion of Phragmites and its control............................................................................................................................ 83 Marsh edaphic algae .......................................................................................................................................................... 86 Submerged aquatic vegetation ........................................................................................................................................... 86 Plant species of special concern......................................................................................................................................... 86 Plankton ..............................................................................................................................................................87 Phytoplankton assemblages ............................................................................................................................................... 87 Zooplankton assemblages.................................................................................................................................................. 89 i Aquatic Macroinvertebrates ................................................................................................................................92 Subtidal benthic/parabenthic macroinvertebrates.............................................................................................................. 92 Marsh surface aquatic macroinvertebrates ........................................................................................................................ 99 Horseshoe crabs............................................................................................................................................................... 104 Saltmarsh Mosquitoes and Their Control........................................................................................................................ 105 Finfishes.............................................................................................................................................................106 Reptiles and Amphibians ...................................................................................................................................109