Governing Ecological Connectivity in Cross-Scale Dependent Systems.

Ecosystem management and governance of cross-scale dependent systems require integrating knowledge about ecological connectivity in its multiple forms and scales. Although scientists, managers, and policymakers are increasingly recognizing the importance of connectivity, governmental organizations may not be currently equipped to manage ecosystems with strong cross-boundary dependencies. Managing the different aspects of connectivity requires building social connectivity to increase the flow of information, as well as the capacity to coordinate planning, funding, and actions among both formal and informal governance bodies. We use estuaries in particular the San Francisco Estuary, in California, in the United States, as examples of cross-scale dependent systems affected by many intertwined aspects of connectivity. We describe the different types of estuarine connectivity observed in both natural and human-affected states and discuss the human dimensions of restoring beneficial physical and ecological processes. Finally, we provide recommendations for policy, practice, and research on how to restore functional connectivity to estuaries

Which Way to the Brave New Baylands?

doi: http://dx.doi.org/10.15447/sfews.2016v14iss1art1&lt;Abstracts are not required to accompany articles in the Essay category. --the Editors of SFEWS&gt;</p

Managed Wetlands for Climate Action: Potential Greenhouse Gas and Subsidence Mitigation in the Sacramento–San Joaquin Delta

In the Sacramento–San Joaquin Delta (Delta), widespread drainage of historical wetlands has led to extensive subsidence and peat carbon losses, as well as high ongoing greenhouse gas (GHG) emissions. Large-scale wetland restoration and conversion to rice fields has the potential to mitigate these effects while conferring flood protection and creating habitat for wetland species. To explore the scale of these potential benefits, this study evaluated the effects of seven Delta-wide land-use scenarios on carbon stocks, land-surface elevation, GHG emissions, and habitat. Peat mapping and data from peat cores indicate that soil carbon stocks have decreased between the early 1800s and 2010s from 288 ± 15 to 145 ± 14 million metric tons (Mt) of carbon (C). If existing land uses continue, the Delta could lose an additional 8.3&nbsp;Mt C during the coming 40 years, equal to average GHG emissions of 1.2&nbsp;Mt CO2 equivalents (CO2e) yr-1. Future restoration and rice-farming scenarios indicate that wetland restoration could theoretically halt GHG emissions, converting the Delta from a large GHG source to a weak net source or sink. Across three future scenarios based on existing restoration targets, wetland creation and conversion to rice fields reduced GHG emissions by 0.39 to 0.67&nbsp;Mt CO2e yr-1, with per-area benefits of 16 to 28 t CO2e per hectare (ha) yr-1. Differences among scenarios in extents of wetland types influenced their relative benefits for different management goals. Tidal restoration and conversion to rice fields enhanced habitat benefits and offered a source of agricultural income, but with reduced GHG mitigation compared with conversion to peat-building wetlands. This highlights the importance of clear objectives when developing land-use plans. A strategic land-management portfolio that includes rice fields and both impounded and tidal wetlands could be designed to provide GHG and subsidence mitigation while offering a diverse suite of benefits for ecosystems and people

Seasonal and annual trends in forage fish mercury concentrations, San Francisco Bay

San Francisco Bay is contaminated by mercury (Hg) due to historic and ongoing sources, and has elevated Hg concentrations throughout the aquatic food web. We monitored Hg in forage fish to indicate seasonal and interannual variations and trends. Interannual variation and long-term trends were determined by monitoring Hg bioaccumulation during September-November, for topsmelt (Atherinops affinis) and Mississippi silverside (Menidia audens) at six sites, over six years (2005 to 2010). Seasonal variation was characterized for arrow goby (Clevelandia ios) at one site, topsmelt at six sites, and Mississippi silverside at nine sites. Arrow goby exhibited a consistent seasonal pattern from 2008 to 2010, with lowest concentrations observed in late spring, and highest concentrations in late summer or early fall. In contrast, topsmelt concentrations tended to peak in late winter or early spring and silverside seasonal fluctuations varied among sites. The seasonal patterns may relate to seasonal shifts in net MeHg production in the contrasting habitats of the species. Topsmelt exhibited an increase in Alviso Slough from 2005 to 2010, possibly related to recent hypoxia in that site. Otherwise, directional trends for Hg in forage fish were not observed. For topsmelt and silverside, the variability explained by year was relatively low compared to sampling station, suggesting that interannual variation is not a strong influence on Hg concentrations. Although fish Hg has shown long-term declines in some ecosystems around the world, San Francisco Bay forage fish did not decline over the six-year monitoring period examined.11 page(s

Primary Production in the Delta: Then and Now

To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function. Primary production is a crucial ecosystem process, which directly limits the quality and quantity of food available for secondary consumers such as invertebrates and fish. The Delta has a low rate of primary production, but it is unclear whether this was always the case. Recent analyses from the Historical Ecology Team and Delta Landscapes Project provide quantitative comparisons of the areal extent of 14 habitat types in the modern Delta versus the historical Delta (pre-1850). Here we describe an approach for using these metrics of land use change to: (1) produce the first quantitative estimates of how Delta primary production and the relative contributions from five different producer groups have been altered by large-scale drainage and conversion to agriculture; (2) convert these production estimates into a common currency so the contributions of each producer group reflect their food quality and efficiency of transfer to consumers; and (3) use simple models to discover how tidal exchange between marshes and open water influences primary production and its consumption. Application of this approach could inform Delta management in two ways. First, it would provide a quantitative estimate of how large-scale conversion to agriculture has altered the Delta's capacity to produce food for native biota. Second, it would provide restoration practitioners with a new approach—based on ecosystem function—to evaluate the success of restoration projects and gauge the trajectory of ecological recovery in the Delta region

Primary Production in the Delta: Then and Now

To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function. Primary production is a crucial ecosystem process, which directly limits the quality and quantity of food available for secondary consumers such as invertebrates and fish. The Delta has a low rate of primary production, but it is unclear whether this was always the case. Recent analyses from the Historical Ecology Team and Delta Landscapes Project provide quantitative comparisons of the areal extent of 14 habitat types in the modern Delta versus the historical Delta (pre-1850). Here we describe an approach for using these metrics of land use change to: (1) produce the first quantitative estimates of how Delta primary production and the relative contributions from five different producer groups have been altered by large-scale drainage and conversion to agriculture; (2) convert these production estimates into a common currency so the contributions of each producer group reflect their food quality and efficiency of transfer to consumers; and (3) use simple models to discover how tidal exchange between marshes and open water influences primary production and its consumption. Application of this approach could inform Delta management in two ways. First, it would provide a quantitative estimate of how large-scale conversion to agriculture has altered the Delta's capacity to produce food for native biota. Second, it would provide restoration practitioners with a new approach—based on ecosystem function—to evaluate the success of restoration projects and gauge the trajectory of ecological recovery in the Delta region

Primary Production in the Delta: Then and Now

doi: http://dx.doi.org/10.15447/sfews.2016v14iss3art1To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function. Primary production is a crucial ecosystem process, which directly limits the quality and quantity of food available for secondary consumers such as invertebrates and fish. The Delta has a low rate of primary production, but it is unclear whether this was always the case. Recent analyses from the Historical Ecology Team and Delta Landscapes Project provide quantitative comparisons of the areal extent of 14 habitat types in the modern Delta versus the historical Delta (pre-1850). Here we describe an approach for using these metrics of land use change to: (1) produce the first quantitative estimates of how Delta primary production and the relative contributions from five different producer groups have been altered by large-scale drainage and conversion to agriculture; (2) convert these production estimates into a common currency so the contributions of each producer group reflect their food quality and efficiency of transfer to consumers; and (3) use simple models to discover how tidal exchange between marshes and open water influences primary production and its consumption. Application of this approach could inform Delta management in two ways. First, it would provide a quantitative estimate of how large-scale conversion to agriculture has altered the Delta's capacity to produce food for native biota. Second, it would provide restoration practitioners with a new approach—based on ecosystem function—to evaluate the success of restoration projects and gauge the trajectory of ecological recovery in the Delta region.</p