Using New Methodologies to Assess Bar-Built Estuaries Along The

Central Coast Wetlands Group Using New Methodologies to Assess Bar-built Estuaries along California’s Coastline Final Report Ross Clark, Cara Clark, Walter Heady, Kevin O’Connor, Sierra Ryan and Sarah Stoner-Duncan November 30, 2013 1 Table of Contents 1. Bar Built Estuary Definition and Inventory ................................................................................. 3 Introduction ................................................................................................................................ 3 BBE Management ................................................................................................................... 3 Definition .................................................................................................................................... 4 Conceptual Model ....................................................................................................................... 5 Characteristic Hydrologic Processes: ...................................................................................... 6 Characteristic Sediment Processes: ........................................................................................ 8 Bar Formation: ........................................................................................................................ 9 Emergent Marsh Community: .............................................................................................. 10 System Functions: ................................................................................................................. 10 Anthropogenic Stressors: ...................................................................................................... 11 Inventory and Classification ...................................................................................................... 12 CCWG Coastal Confluence Classifications ............................................................................ 14 2. CRAM Module Validation .......................................................................................................... 18 Introduction .............................................................................................................................. 18 Methods .................................................................................................................................... 19 Overview of CRAM ................................................................................................................ 21 Study sites ............................................................................................................................. 21 Validation of CRAM ............................................................................................................... 22 Validation analyses ............................................................................................................... 24 Range and representativeness ............................................................................................. 24 Responsiveness ..................................................................................................................... 25 Redundancy .......................................................................................................................... 29 Reproducibility ...................................................................................................................... 29 Results ....................................................................................................................................... 29 Range and representativeness ............................................................................................. 29 Responsiveness ..................................................................................................................... 30 Redundancy .......................................................................................................................... 34 Reproducibility ...................................................................................................................... 34 Discussion.................................................................................................................................. 34 1 Calibration and Standardization ........................................................................................... 35 Evaluation ............................................................................................................................. 35 3. Historical Assessment of BBE Change ....................................................................................... 39 Statewide Assessment .............................................................................................................. 43 Regional Assessment ................................................................................................................ 44 Site Specific Assessment ........................................................................................................... 46 Conclusion ................................................................................................................................. 47 4. Bar Built Estuary Condition Assessment ................................................................................... 48 Sample description ................................................................................................................... 48 Condition Assessment Results .................................................................................................. 52 Range of Scores by Region .................................................................................................... 52 Comparison of CRAM Metric Results .................................................................................... 55 Wetland Condition Groups ....................................................................................................... 55 Adjacent Land Uses and Anthropogenic Stresses ..................................................................... 58 Relationship between adjacent land use stressors and CRAM Index score ......................... 59 Indicators of Marsh Plain Degradation ..................................................................................... 61 Loss of Wetland Area ............................................................................................................ 61 Mouth Management and Resulting Impacts on BBE Hydrology .............................................. 62 Marsh Plain Innundation .......................................................................................................... 62 Marsh Plain Vegetation............................................................................................................. 64 Central Coast Ambient Assessment .......................................................................................... 66 Introduction .......................................................................................................................... 66 Data Collected ....................................................................................................................... 67 Results ................................................................................................................................... 68 5. Outreach and Education ........................................................................................................... 71 Museum Exhibit ........................................................................................................................ 71 Presentations ............................................................................................................................ 74 6. Conclusions and Future Research ............................................................................................. 76 Acknowledgements ....................................................................................................................... 78 References .................................................................................................................................... 79 2 1. Bar Built Estuary Definition and Inventory Introduction Connecting marine, freshwater and terrestrial ecosystems, bar-built estuaries (BBE), often referred to as coastal lagoons, are complex and dynamic systems. BBEs are unique in the world in that they are mostly located along high wave energy coasts, with swell‐exposed beaches, and are associated with streams that often have high seasonal discharge. BBEs are only found in the Central West Coast of North America, East and South Coast of Australia, East Coast of South America, South Africa and part of the West Coast of France. These systems fluctuate between fresh and brackish conditions, providing a wide range of unique ecological services that benefit rare and endangered species. These types of coastal confluences are generally found at the mouths of watersheds in Mediterranean climates with episodic streamflow and seasonal fluctuations in swell dynamics (Haines et al. 2006). The typical BBE formation pattern is 1) high stream flows coupled with strong swells keep the stream mouth open in the winter; 2) low stream flows and a concomitant shift in swells during summers cause a sand bar to form at the mouth restricting or isolating the stream from the ocean, pooling fresh and marine waters within a rising estuary, 3) water elevation rises behind

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