Ronald M. Thom

Functional Equivalency Trajectories of the Restored Gog‐Le‐Hi‐Te Estuarine Wetland

Assessing performance of restored and created wetlands for compensatory mitigation and restoration poses a mismatch between long-term processes and the short- term expediency of management decisions. If they were predictable, patterns in the temporal development of important wetland processes could reduce long-term uncertainty of the outcome of restoration projects. To test our ability to predict long-term trends and patterns in the development of a restored wetland based on the first 7 yr of its development, we analyzed 16 ecosystem functional attributes of the Gog-Le-Hi-Te Wetland, in the Puyallup River estuary, Puget Sound, Washington, USA. This estuarine wetland system was restored to tidal inundation in 1986. Only a few of the 16 ecosystem attributes analyzed showed functional trajectories toward equivalency with natural wetlands, and many were incon- clusive or suggested disfunction relative to reference wetlands. Natural variability among reference sites also inhibited our ability to interpret an expected asymptote in developmental trajectories. The ability of wetland managers to assess compensatory-mitigation success over short- term (e.g., regulatory) timeframes depends upon the selection of wetland attributes that can predict long-term trends in the development of the restored/created system. However, we are hampered by a basic lack of long-term data sets describing the patterns, trends, and variability in natural wetland responses to disturbance, as well as natural variability in wetland attributes in presumably mature wetland communities. Ultimately, it may be nec- essary to supplant our descriptive means of assessing functional equivalency with simple, controlled manipulative experiments or assays, standardized across restoration/mitigation and reference sites.

Landscape Structure and Scale Constraints on Restoring Estuarine Wetlands for Pacific Coast Juvenile Fishes

Juveniles of many Pacific Northwest coastal fishes and particularly anadromous species, utilise coastal marshes as “nursery” habitats, predicating the assumption that restoration of marsh sites will promote increased fish survival and production. However, species such as anadromous salmonids have evolved life history strategies that to various degrees depend upon the structure and scale of the estuarine landscape rather than habitat sites per se. Examples include: 1) migration of juvenile salmon among interconnected wetlands along estuarine gradient, 2) their access to dendritic tidal channels, and 3) extended residence in tidal freshwater sloughs. Unfortunately, estuarine habitat restoration is seldom designed or implemented with landscape structure and scale in mind, ignoring important landscape attributes and processes such as habitat matrix heterogeneity, dendritic tidal channel complexity, allometric relationships of estuarine sloughs, and disturbance frequency and intensity. In this analysis, we draw on several estuarine wetland mitigation and restoration sites in the Pacific Northwest to explore the effect of estuarine landscape structure and scale on their effectiveness for protecting and rehabilitating coastal fisheries resources. We argue that basing restoration solely on site-specific criteria may be significantly inhibiting our ability to re-establish estuarine support function for fisheries resources. To significantly recover the function of juvenile fish migration and survival in coastal ecosystems, future marsh restoration must be conceptualized, designed, constructed and assessed taking into account estuarine landscape structure and scale.

CO2-Enrichment effects on eelgrass (Zostera marina L.) and bull kelp (Nereocystis luetkeana (mert.) P & R.)

I investigated the effect of CO2-enrichment on productivity of two aquatic plant species [Zostera marina L., Nereocystis luetkeana (Mert.) P. & R.] that form significant components of coastal ecosystems in the Pacific Northwest. Short-term (i.e., 2-hr) experiments showed that doubling CO2 resulted in up to a 2.5-fold increase in Zostera net apparent productivity (NAP). Nereocystis NAP was increased 2.2 – 2.8 fold. In experiments involving seven enrichment treatments, NAP increased with increasing CO2 between ambient (1.0×) and 2.5× CO2 in both Zostera and Nereocystis. Nereocystis and Zostera NAP was lowest at highest (i.e., 5×) CO2 concentrations. In growth experiments, mean growth rate of Zostera increased with increasing CO2 during one of the two trials. I conclude that increasing CO2 in the surface waters of the coastal ocean would predictably result in increased NAP of these two species. These results supplement limited published data showing that shallow estuarine and marine systems are vulnerable to increased carbon dioxide.

Planning aquatic ecosystem restoration monitoring programs

This study was conducted as part of the Evaluation of Environmental Investments Research Program (EEIRP). The EEIRP is sponsored by the US Army Corps of Engineers. The objectives of this work are to (1) identify relevant approaches and features for environmental investment measures to be applied throughout the project life; (2) develop methods to access the effectiveness of the approach or feature for providing the intended environmental output; (3) develop and provide guidance for formulating environmental projects; and (4) provide guidance for formulating and identifying relevant cost components of alternate restoration plans.

Multiscale Analysis of Restoration Priorities for Marine Shoreline Planning

Planners are being called on to prioritize marine shorelines for conservation status and restoration action. This study documents an approach to determining the management strategy most likely to succeed based on current conditions at local and landscape scales. The conceptual framework based in restoration ecology pairs appropriate restoration strategies with sites based on the likelihood of producing long-term resilience given the condition of ecosystem structures and processes at three scales: the shorezone unit (site), the drift cell reach (nearshore marine landscape), and the watershed (terrestrial landscape). The analysis is structured by a conceptual ecosystem model that identifies anthropogenic impacts on targeted ecosystem functions. A scoring system, weighted by geomorphic class, is applied to available spatial data for indicators of stress and function using geographic information systems. This planning tool augments other approaches to prioritizing restoration, including historical conditions and change analysis and ecosystem valuation.

A Levels-of-Evidence Approach for Assessing Cumulative Ecosystem Response to Estuary and River Restoration Programs

Large-scale ecological restoration programs are beginning to supplement isolated projects implemented on rivers and tidal waterways. Nevertheless, the effects of estuary and river restoration often continue to be evaluated at local project scales or by integration in an additive manner. Today, we have sufficient scientific understanding to apply knowledge gained from measuring cumulative impacts of anthropogenic stressors on ecosystems to assessment of ecological restoration. Integration of this knowledge has potential to increase the efficacy of restoration projects that are conducted at several locations but comanaged within the confines of a larger integrative program. We introduce a framework based on a levels-of-evidence approach that facilitates assessment of the cumulative landscape effects of individual restoration actions taken at many different locations. It incorporates data collection at restoration and reference sites, hydrodynamic modeling, geographic information systems, and meta-analyses in a five-stage process: design, data development, analysis, synthesis and evaluation, and application. This framework evolved from the need to evaluate the efficacy of restoration projects that are being implemented in numerous wetlands on the 235 km tidal portion of the Columbia River, USA, which are intended to increase rearing habitat for out-migrating juvenile salmonid fishes.

Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2006

The goal of this multi-year study (2004-2010) is to develop a methodology to evaluate the cumulative effects of multiple habitat restoration projects intended to benefit ecosystems supporting juvenile salmonids in the lower Columbia River and estuary. Literature review in 2004 revealed no existing methods for such an evaluation and suggested that cumulative effects could be additive or synergistic. Field research in 2005, 2006, and 2007 involved intensive, comparative studies paired by habitat type (tidal swamp vs. marsh), trajectory (restoration vs. reference site), and restoration action (tide gate vs. culvert vs. dike breach). The field work established two kinds of monitoring indicators for eventual cumulative effects analysis: core and higher-order indicators. Management implications of limitations and applications of site-specific effectiveness monitoring and cumulative effects analysis were identified.

Climate-linked Mechanisms Driving Spatial and Temporal Variation in Eelgrass (Zostera marina L.) Growth and Assemblage Structure in Pacific Northwest Estuaries, U.S.A.

ABSTRACT Thom, R.; Southard, S., and Borde, A., 2014. Climate-linked mechanisms driving spatial and temporal variations in eelgrass (Zostera marina L.) growth and assemblage structure in Pacific Northwest estuaries, USA. Using laboratory experiments on temperature and leaf metabolism, and field data sets from Washington, between 1991 and 2013, we developed lines of evidence showing that variations in water temperature, mean sea level, and desiccation stress appear to drive spatial and temporal variations in eelgrass (Zostera marina). Variations in the Oceanic Niño Index (ONI) and mean sea level (MSL), especially during the strong 1997–2001 El Niño-La Niña event, corresponded with variations in leaf growth rate of an intertidal population. Field studies suggested that this variation was associated with both desiccation period and temperature. Subtidal eelgrass shoot density recorded annually over a 10-year period was lowest during the warm and cool extremes of sea surface temperature. These periods corresponded to the extremes in the ONI. Variations in density of a very low intertidal population in a turbid estuary were explained by both variations in temperature and light reaching the plants during periods of higher MSL. These results show complex interactions between water-level variation, temperature and light as mechanisms regulating variation in eelgrass, which complicates the ability to predict the effects of climate variation and change on this important resource. Because of the extensive wide geographic distribution of eelgrass, its tractability for study, and its responsiveness to climate, this and other seagrass species should be considered useful indicators of the effects of climate variation and change on marine and estuarine ecosystems.

Lower Columbia River and Estuary Habitat Restoration Prioritization Framework

The Restoration Prioritization Framework was designed as a decision-making tool for the Lower Columbia River Estuary Partnership, to help identify the highest-priority sites for restoration. The underlying concepts are derived from regional applications of aquatic restoration theory. The framework uses the conceptual model that physical controlling factors (e.g., light, temperature, hydrology) drive the formation and maintenance of habitats and their ecological functions, and that stressors act on the controlling factors. The framework is two tiered and comprises 1) an overview of the concepts and description of framework tools; 2) a spreadsheet containing detailed data, formulas, and workflow for the actual site prioritization; and 3) a geographic information system (GIS) database containing source and processed geospatial datasets. In Tier I, the framework uses a GIS-based approach to evaluate impacts from a variety of human “stressors” such as diking, agriculture, overwater structures, and flow restrictions. Data processing derives priority scores, which are then relinked to the geographic sites in the GIS. In this manner, all of the data and tools employed can be analyzed and queried in a geospatial context. In addition to the core impact assessment, the framework includes tools to incorporate information on hydrologic connectivity and existing function into the priority screening. Specific restoration project proposals are evaluated in Tier II, using information on cost, expected functional change, site size, and predicted probability of success. Using this framework, the Lower Columbia River Estuary Partnership can screen for impacted areas, prioritize areas based on desired ecological criteria, and evaluate selected projects.

Adaptive management of large aquatic ecosystem recovery programs in the United States

Adaptive management (AM) is being employed in a number of programs in the United States to guide actions to restore aquatic ecosystems because these programs are both expensive and are faced with significant uncertainties. Many of these uncertainties are associated with prioritizing when, where, and what kind of actions are needed to meet the objectives of enhancing ecosystem services and recovering threatened and endangered species. We interviewed nine large-scale aquatic ecosystem restoration programs across the United States to document the lessons learned from implementing AM. In addition, we recorded information on ecological drivers (e.g., endangered fish species) for the program, and inferred how these drivers reflected more generic ecosystem services. Ecosystem services (e.g., genetic diversity, cultural heritage), albeit not explicit drivers, were either important to the recovery or enhancement of the drivers, or were additional benefits associated with actions to recover or enhance the program drivers. Implementing programs using AM lessons learned has apparently helped achieve better results regarding enhancing ecosystem services and restoring target species populations. The interviews yielded several recommendations. The science and AM program must be integrated into how the overall restoration program operates in order to gain understanding and support, and effectively inform management decision-making. Governance and decision-making varied based on its particular circumstances. Open communication within and among agency and stakeholder groups and extensive vetting lead up to decisions. It was important to have an internal agency staff member to implement the AM plan, and a clear designation of roles and responsibilities, and long-term commitment of other involved parties. The most important management questions and information needs must be identified up front. It was imperative to clearly identify, link and continually reinforce the essential components of an AM plan, including objectives, constraints, uncertainties, hypotheses, management actions, decision criteria and triggers, monitoring, and research. Some employed predictive models and the results of research on uncertainties to vet options for actions. Many relied on best available science and professional judgment to decide if adjustments to actions were needed. All programs emphasized the need to be nimble enough to be responsive to new information and make necessary adjustments to management action implementation. We recommend that ecosystem services be explicit drivers of restoration programs to facilitate needed funding and communicate to the general public and with the global efforts on restoring and conserving ecosystems.