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The search for novel approaches to establishing ecological baselines (reference conditions) is constrained by the fact that most ecological studies span the past few decades, at most, and investigate ecosystems that have been substantially altered by human activities for decades, centuries, or more. Paleobiology, archeology, and history provide historical ecological context for biological conservation, remediation, and restoration. We argue that linking historical ecology explicitly with conservation can help unify related disciplines of conservation paleobiology, conservation archeobiology, and environmental history. Differences in the spatial and temporal resolution and extent (scale) of prehistoric, historic, and modern ecological data remain obstacles to integrating historical ecology and conservation biology, but the prolonged temporal extents of historical ecological data can help establish more complete baselines for restoration, document a historical range of ecological variability, and assist in determining desired future conditions. We used the eastern oyster (Crassostrea virginica) fishery of the Chesapeake Bay (U.S.A.) to demonstrate the utility of historical ecological data for elucidating oyster conservation and the need for an approach to conservation that transcends disciplinary boundaries. Historical ecological studies from the Chesapeake have documented dramatic declines (as much as 99%) in oyster abundance since the early to mid-1800s, changes in oyster size in response to different nutrient levels from the sixteenth to nineteenth centuries, and substantial reductions in oyster accretion rates (from 10 mm/year to effectively 0 mm/year) from the Late Holocene to modern times. Better integration of different historical ecological data sets and increased collaboration between paleobiologists, geologists, archeologists, environmental historians, and ecologists to create standardized research designs and methodologies will help unify prehistoric, historic, and modern time perspectives on biological conservation. La búsqueda de métodos nuevos para establecer líneas de base ecológicas (condiciones de referencia) está limitada por el hecho de que la mayoría de los estudios ecológicos abarcan las últimas décadas, cuando mucho, e investigan ecosistemas que han sido alterados sustancialmente por actividades humanas, por décadas, siglos o, posiblemente, más. La paleobiología, arqueología e historia proporcionan contexto ecológico histórico a la biología de la conservación, la remediación y restauración. Argumentamos que la integración explícita de la ecología histórica con la conservación puede ayudar a unificar disciplinas relacionadas de paleobiología de la conservación, arqueobiología de la conservación e historia ambiental. Diferencias en la resolución espacial y temporal y la extensión (escala) de datos prehistóricos, históricos y modernos aun son obstáculos para la integración de la ecología histórica y la biología de la conservación, pero las extensiones temporales prolongadas de datos ecológicos históricos pueden ayudar a establecer líneas de base más completas para la restauración, documentar un rango histórico de variabilidad ecológica y ayudar a la determinación de condiciones futuras deseadas. Utilizamos la pesquería del ostión oriental (Crassostrea virginica) de la Bahía de Chesapeake (E.U.A.) para demostrar la utilidad de los datos ecológicos históricos para dilucidar la conservación del ostión y la necesidad de un método de conservación que trascienda límites disciplinares. Los estudios ecológicos históricos de Chesapeake han documentado declinaciones dramáticas (tanto como 99%) en la abundancia de ostiones de inicios a mediados de los 1800, cambios en el tamaño de ostiones en respuesta a diferentes niveles de nutrientes del siglo dieciséis al diecinueve y reducciones sustanciales en las tasas de acreción de ostiones (de 10 mm/año a 0 mm/año) desde el Holoceno Tardío a tiempos modernos. Una mejor integración de diferentes conjuntos de datos ecológicos históricos y una mayor colaboración entre paleobiólogos, geólogos, arqueólogos, historiadores ambientales y ecólogos para definir diseños de investigación estandarizados y metodologías ayudarán a unificar perspectivas de la biología de la conservación prehistóricas, históricas y modernas.

A gridded model was developed to simulate the hydrology of the Chesapeake Bay Watershed, the largest estuary in the United States. CMIP3 and CMIP5 climate projections were used to drive the model to assess changes in streamflow and watershed-wide hydrology. Index of agreement values indicated good model performance. Annual average temperature is projected to increase 1.9°C to 5.4°C by 2080 to 2099, with the greatest warming occurring in summer and fall in the northern part of the watershed. Annual total precipitation is projected to increase between 5.2 percent and 15.2 percent by 2080 to 2099, with the largest increases generally occurring in winter. Average evapotranspiration and rainfall are projected to increase while snowfall, snow water storage, and snowmelt decrease. Subsurface moisture is projected to decrease during the warmer months and the time to recharge increases and, in some cases, never actually occurs. Changes in annual runoff for all 346 climate projections averaged 0 percent (2020-2039), -1.5 percent (2050-2069), and -5.1 percent (2080-2099). There is a 48 percent, 52 percent, and 60 percent chance, respectively, for the future time periods that annual runoff will be less than baseline values (1950-1999). Extreme runoff projections are overwhelmingly associated with the negative end of the distribution. Runoff increases are confined to January through March and to higher elevations. This study is novel in its use of a large number of climate models, the gridded nature of the hydrologic model, and the simulation of several hydrologic variables, all of which allowed for the assessment of both uncertainty in the projections and variation across multiple spatial and temporal scales.