A CONSERVATION ASSESSMENT OF WEST COAST (USA) ESTUARIES Mary G. Gleason, Sarah Newkirk, Matthew S. Merrifield, Jeanette Howard, Robin Cox, Megan Webb, Jennifer Koepcke, Brian Stranko, Bethany Taylor, Michael W. Beck, Roger Fuller, Paul Dye, Dick Vander Schaaf, and Jena Carter CONTENTS Executive Summary ..........................................................................................................................1 1.0 Introduction ..................................................................................................................................4 2.0 Conservation Planning for West Coast Estuaries ........................................................8 3.0 Classifying West Coast Estuaries ..................................................................................24 4.0 The Human Footprint ..........................................................................................................30 5.0 Pathways for Enhanced Conservation of West Coast Estuaries......................40 6.0 A Regional Vision and Goals for Improved Estuary Conservation..................50 SUGGESTED CITATION Gleason MG, S Newkirk, MS Merrifield, J Howard, R Cox, M Webb, J Koepcke, B Stranko, B Taylor, MW Beck, R Fuller, P Dye, D Vander Schaaf, J. Carter 2011. A Conservation Assessment of West Coast (USA) Estuaries. The Nature Conservancy, Arlington VA. 65pp. ACKNOWLEDGEMENTS We appreciate the input of the many colleagues who contributed to this assessment by providing data, comments, and recommendations based on their personal and professional experience. We also thank the many conservation practitioners, managers, and stakeholders who are working diligently to conserve and restore estuarine ecosystems on the West Coast. Funding for this assessment was provided by the David and Lucile Packard Foundation. FUNDED BY The David and Lucile Packard Foundation Cover photo: © Rebecca Wells / TNC EXECUTIVE SUMMARY © Bridget Besaw The land-sea interface is one of the most ecologically rich This assessment outlines an enhanced planning approach and complex areas on Earth. Occupying the unique zone for West Coast estuaries that incorporates an evaluation where terrestrial, freshwater, and marine realms converge, of the regional context for estuarine conservation and estuaries are shaped by complex exchanges of energy, recommends an approach to site-scale planning with water, nutrients, sediments, and biota. They are enormously more focus on ecological processes and functions. At productive areas, providing habitat for an extraordinary the regional scale, conservation planning should seek to array of fish, shellfish, birds, and mammals. provide context (status of conservation targets, distribution of threats, management and ownership patterns, Coastal areas where estuaries are found are also home conservation opportunities) supporting conservation to more than sixty percent of humanity. This isn’t a investment at individual estuaries, as well as to identify coincidence: people gravitate toward coastal areas groupings of estuaries that share similar features because they provide numerous ecosystem services (conservation targets, threats, ownership patterns, type upon which we depend. However, dense human of estuary) for multi-site conservation strategies. At the habitation comes with a cost—temperate estuaries site scale, conservation plans should aim to maintain are some of the most degraded environments on the the full spectrum of estuary zones, processes and planet, making their protection and restoration a top functions; safeguard critical connections among terrestrial, conservation priority. freshwater, and marine realms; and safeguard ecosystem service values. At the same time, site-scale efforts should While significant progress has been made over the past be grounded in a regional context and geared toward few decades in improving estuarine water quality, restoring delivering conservation outcomes that have relevance at wetland habitats, and incorporating estuarine habitats into scale. Further, ecological linkages should be considered managed areas, estuarine conservation efforts along the when developing conservation action plans to promote United States (U.S.) West Coast—including Washington, the long-term viability of estuaries. Rather than using Oregon, and California—have generally proceeded on a only species- and habitat-level conservation targets, an bay-by-bay basis, with relatively little coordination among enhanced conservation planning approach for estuaries sites or across the region. In addition, conservation should incorporate ecological processes, functions, and planning for estuaries has not historically been well other system-level conservation targets that integrate integrated across terrestrial, freshwater, and marine realms across terrestrial, freshwater, and marine realms. to address cross-realm threats to estuarine health. Given Understanding how different stressors act to alter those the strong similarities in basic ecology and threats faced processes and functions is critical to developing effective by many of the region’s estuaries, a coordinated effort to conservation strategies. assess regional patterns and develop integrated multi-site strategies is likely to improve conservation effectiveness at both the local and regional scales. 1 This assessment is based, in part, on a geographic Regional scale characterization of the distribution of information system (GIS) database that contains spatial biodiversity, threats and human uses, ownership, and data for 146 estuaries and their associated catchments existing protected lands and waters provides context for (adjacent watersheds) in California, Oregon, and the development of conservation strategies. Patterns of Washington. The West Coast Estuary Database provides distribution of some elements of biodiversity, such as regional data for characterization of spatial patterns of the wetlands, floodplains, Important Bird Areas, and Salmon distribution of selected biodiversity targets and threats. Strongholds, were characterized for the region. There are This database, available to both technical and non- roughly 700,000 acres of tidal and freshwater wetlands in technical users (go to http://www.tnccmaps.org/estuaries estuarine watersheds in the region, with especially high for more information), includes 27 variables that concentrations in San Francisco Bay, Puget Sound, and characterize some key biophysical and human use Coos Bay, OR. While some West Coast estuaries are parameters of these estuaries. characterized by a great deal of floodplain or wetland habitat, a large amount of these habitats has been A hierarchical classification system was developed for converted to urban and agricultural land cover, reducing West Coast estuaries that identified three regions (based current distribution to a fraction of historical extent. West on climate, latitude, and oceanography) and four estuary Coast estuaries are important nursery areas for juveniles types distinguished by the relative degree of influence of of many marine fish and invertebrates. Because a the hydrodynamic forcing mechanisms of waves, tides, and regional assessment of nursery habitat for marine fish rivers. While some estuaries exist along a continuum that has not yet been completed, this assessment assembled is influenced strongly by seasonal or latitudinal patterns, a database documenting presence of juveniles of West Coast estuaries were classified into one of four types: selected commercially-important species in West Coast estuaries. Formerly-extensive native oyster beds have been • River mouth estuaries are dominated by river energy; reduced to remnant populations in most bays in the study • Coastal lagoons are dominated by wave energy; area. Finally, West Coast estuaries are key habitat for • Tidal bay estuaries are deeper-water features that are salmonids; the Columbia River, Klamath River, Whidbey dominated by tidal energy; and Basin, and San Francisco Bay Delta estuaries rank the highest in numbers of robust salmonid populations. • Classic estuaries are influenced by all three controlling factors (river, tide, wave). Several key threats to estuaries were identified for the These predominant hydrodynamic energy sources play a region: key role in structuring estuaries and influence their susceptibility to different threats. • Altered tidal exchange • Altered nutrient dynamics and water quality • Altered freshwater inputs • Altered sediment regime • Invasive species • Direct habitat loss • Climate change Human beings are an undeniably prominent feature of the landscape and seascape of West Coast estuaries. Agriculture and forestry dominate the catchments of many estuaries, while others have large urban centers, and still others remain in a largely natural state. An understanding of patterns of land tenure (ownership), land cover, and predominant land uses in estuary catchments is essential for strategy development as these parameters represent different threats and different opportunities for conservation. Patterns of public and private land ownership influence conservation and stewardship efforts in the region. Private land dominates the upland catchment areas; the main private landowners on a per acre basis are timber companies. Overall, managed lands account for only 25% of the total area of estuary catchments in the region, however 60% of estuaries have at least 10% of their catchments in managed areas. Only 8% of open water © Steve Mlodinow 2 and marshes associated with estuaries