Estuaries are subjected to multiple anthropogenic stressors, which have additive, antagonistic or synergistic effects. Current challenges include the use of large databases of biological monitoring surveys (e.g. the European Water Framework Directive) to help environmental managers prioritizing restoration measures. This study investigated the impact of nine stressor categories on the fish ecological status derived from 90 estuaries of the North East Atlantic countries. We used a random forest model to: 1) detect the dominant stressors and their non-linear effects; 2) evaluate the ecological benefits expected from reducing pressure from stressors; and 3) investigate the interactions among stressors. Results showed that largest restoration benefits were expected when mitigating water pollution and oxygen depletion. Non-additive effects represented half of pairwise interactions among stressors, and antagonisms were the most common. Dredged sediments, flow changes and oxygen depletion were predominantly implicated in non-additive interactions, whereas the remainder stressors often showed additive impacts. The prevalence of interactive impacts reflects a complex scenario for estuaries management; hence, we proposed a step-by-step restoration scheme focusing on the mitigation of stressors providing the maximum of restoration benefits under a multi-stress context.
At the national level, with a fixed amount of resources available for public investment in the restoration of biodiversity, it is difficult to prioritize alternative restoration projects. One way to do this is to assess the level of ecosystem services delivered by these projects and to compare them with their costs. The challenge is to derive a common unit of measurement for ecosystem services in order to compare projects which are carried out in different institutional contexts having different goals (application of environmental laws, management of natural reserves, etc.). This paper assesses the use of habitat equivalency analysis (HEA) as a tool to evaluate ecosystem services provided by restoration projects developed in different institutional contexts. This tool was initially developed to quantify the level of ecosystem services required to compensate for non-market impacts coming from accidental pollution in the US. In this paper, HEA is used to assess the cost effectiveness of several restoration projects in relation to different environmental policies, using case studies based in France. Four case studies were used: the creation of a market for wetlands, public acceptance of a port development project, the rehabilitation of marshes to mitigate nitrate loading to the sea, and the restoration of streams in a protected area. Our main conclusion is that HEA can provide a simple tool to clarify the objectives of restoration projects, to compare the cost and effectiveness of these projects, and to carry out trade-offs, without requiring significant amounts of human or technical resources.
Since 1996, the watershed approach (i.e., the inclusive use of watershed information) has been a hallmark concept in ecosystem restoration site location. In 2008, federal regulators required use of the watershed approach in siting compensatory mitigation for aquatic impacts regulated under the U.S. Clean Water Act. However, regulations fell short of requiring full watershed plans, which could have required stakeholder involvement and inter-institutional coordination. Little work has evaluated how the watershed approach or planning position mitigation sites in the landscape. Has the watershed approach or watershed planning been successful in targeting restoration sites where they are needed? The North Carolina Division of Mitigation Services (DMS; formerly the NC Ecosystem Enhancement Program), a state agency, has implemented the watershed approach and extensive watershed planning to focus restoration investments. Through a multi-step planning program, the DMS employs a watershed approach to gauge the need of 12-digit watersheds for restoration. In some cases, an intensive local watershed planning process follows this targeting effort. We tested the effect of the program’s watershed targeting approach (n = 710) and local watershed planning efforts (n = 147) on increasing the frequency of wetland and stream mitigation projects (n = 480) in each of the state’s 1741 12-digit watersheds (1998–2012). We find that while the watershed approach is successful at guiding restoration to targeted watersheds over space and time, the impacts of watershed planning are more nebulous, with important but weaker panel-effects. Our findings highlight the importance of plan quality and data management in using a watershed approach to target restoration sites effectively.
Habitat loss and disturbance are ranked globally as the greatest threats to biodiversity. Development and coastal population growth are the leading causes for habitat losses. Recently, the restoration of marine habitats has increased, especially with the goal of increasing non-consumptive ecosystem services derived from mangrove and submerged aquatic vegetation (SAV) along with biogenic oyster reefs. Habitats reside in landscapes dominated by multiple species. Rather than focusing on a single habitat such as oysters or mangroves or SAV, we took an approach restoring multiple adjacent habitats to accelerate restoration in a Florida embayment that had been significantly degraded prior to the restoration of natural tidally generated flows. After a multiple habitat die-off, a project was initiated in 2006 to reintroduce tidal flushing. The re-introduction of tidal flushing, however, did not result in immediate recovery of mangrove shorelines or oyster-dominated reefs. There was a lack of mangrove propagule production and significant substrate limitation in areas with appropriate salinity, sediment and tidal flows. From 2009–2012, red mangrove (Rhizophora mangle) propagules were collected (over 500,000) and planted for a total area of 3.24 ha. From 2009–2010, five intertidal reefs were constructed by adding bagged and fossil shell (54 MT) for Crassostrea virginica larvae to recruit onto totaling over 779 m2. Monitoring of planted mangrove versus unplanted shorelines demonstrated that prop root and drop root densities were higher where propagules were planted (28 m−2) versus unplanted (2.3 m−2). Oyster densities and mean sizes (multiple year classes) at new and natural reefs were measured after 8, 12, and 24, and 36 months. An initial settlement pulse was observed in the first 8 months followed by an increase in the density of greater than 1-year old oysters. Xanthid crab densities (Eurypanopeus depressus and Panopeus spp.) in restored reefs and natural reefs were similar, while Petrolisthes armatus densities were lower in restored reefs. Whole reef seston filtration rates over restored reefs were −26 to 157 L m−2 h−1 when measured at 4, 15, 28, and 40 months. A multiple habitat approach may be useful in accelerating the natural ecological succession, especially if the project site has reached a degraded, alternate ecological state. These results suggest a multiple habitat approach can be useful in providing non-provisioning ecosystem services to a Florida embayment.
In the gardening approach for reef restoration, coral stocks are farmed in underwater nurseries (phase I) prior to their transplantation onto degraded reefs (phase II). The phase I aspects were already evaluated in the literature, but very little is known about the phase II outcomes. Assessing phase II feasibility, we transplanted 554 nursery-farmed colonies of two branching species (Stylophora pistillata, Pocillopora damicornis) onto five denuded knolls in Eilat (Red Sea). The performance of the transplants was compared for 17 months with 76 natal colonies and 217 colonies maintained at the coral-nursery. At the natural reef, rates of full/partial mortalities, detachment and fish herbivory were considerably higher than the nursery values. While corallivory on Pocillopora transplants was comparable to that observed in natal colonies, herbivory on Stylophora transplants increased 2.2 fold compared to natal controls. Their survivorship was similar to the survivorship observed in natal colonies in the 9 months post transplantation, but was 30% higher after 17 months. In contrast, no enhanced mortality was documented in Pocillopora transplants throughout the entire period. The detachment levels of the Stylophora and Pocillopora transplants were 3 and 10 times higher, respectively, than those observed in natal colonies, and the growth rates of the transplants were identical to the rates observed in the nursery control groups. Transplants showed a 2.5–3.3 fold increase in colonial ecological-volumes, resulting in enhanced acquired space/habitats for coral-dwelling species like Trapezia, Alpheus, Spirobranchus and Lithophaga. The successful integration of farmed transplants in Eilat’s degraded reef and their provision of new ecological niches for reef-associated fauna, coupled with economic assessments, indicate that transplantation of farmed corals is an easy, cost-effective mean to counteract degradation of coral reefs. Results also imply that the selection of coral species for reef restoration should take into consideration their autogenic/allogenic engineering properties, particularly if the aims are to restore the whole reef community, rather than simply focus on coral coverage.
Restoration activities inherently depend on understanding the spatial and temporal variation in basic demographic rates of the species of interest. For species that modify and maintain their own habitat such as the eastern oyster Crassostrea virginica, understanding demographic rates and their impacts on population and habitat success are crucial to ensuring restoration success. We measured oyster recruitment, density, size distribution, biomass, mortality and Perkinsus marinus infection intensity quarterly for 3 yr on shallow intertidal reefs created with shell cultch in March 2009. All reefs were located within Sister Lake, LA. Reefs were placed in pairs at 3 different locations within the lake; pairs were placed in low and medium energy sites within each location. Restored reefs placed within close proximity (<8 km) experienced very different development trajectories; there was high inter-site and inter-annual variation in recruitment and mortality of oysters, with only slight variation in growth curves. Despite this high variation in population dynamics, all reefs supported dense oyster populations (728 ± 102 ind. m-2) and high live oyster biomass (>14.6 kg m-2) at the end of 3 yr. Shell accretion, on average, exceeded estimated rates required to keep pace with local subsidence and shell loss. Variation in recruitment, growth and survival drives local site-specific population success, which highlights the need to understand local water quality, hydrodynamics, and metapopulation dynamics when planning restoration.
Large-scale aquatic ecosystem restoration is increasing and is often controversial because of the economic costs involved, with the focus of the controversies gravitating to the modeling of fish responses. We present a scheme for best practices in selecting, implementing, interpreting, and reporting of fish modeling designed to assess the effects of restoration actions on fish populations and aquatic food webs. Previous best practice schemes that tended to be more general are summarized, and they form the foundation for our scheme that is specifically tailored for fish and restoration. We then present a 31-step scheme, with supporting text and narrative for each step, which goes from understanding how the results will be used through post-auditing to ensure the approach is used effectively in subsequent applications. We also describe 13 concepts that need to be considered in parallel to these best practice steps. Examples of these concepts include: life cycles and strategies; variability and uncertainty; nonequilibrium theory; biological, temporal, and spatial scaling; explicit versus implicit representation of processes; and model validation. These concepts are often not considered or not explicitly stated and casual treatment of them leads to mis-communication and mis-understandings, which in turn, often underlie the resulting controversies. We illustrate a subset of these steps, and their associated concepts, using the three case studies of Glen Canyon Dam on the Colorado River, the wetlands of coastal Louisiana, and the Everglades. Use of our proposed scheme will require investment of additional time and effort (and dollars) to be done effectively. We argue that such an investment is well worth it and will more than pay back in the long run in effective and efficient restoration actions and likely avoided controversies and legal proceedings.
The Partners for Fish and Wildlife (PFW) Program and Coastal Program are the U.S. Fish and Wildlife Service’s premier conservation delivery tools for voluntary, citizen and community‐based fish and wildlife habitat restoration activities across the matrix of public and privately owned land. The programs work directly with partners to implement vital on‐the‐ground habitat restoration projects across the nation and in U.S. territories.
The PFW and Coastal Programs channel government and private dollars to local communities where they create work to support new jobs and provide income to local contractors and other industries. Money spent in support of projects circulates through the economy, creating more jobs and generating economic activity. The impacts of PFW and Coastal Program funds are multiplied in two dimensions. First, the program expertise and funding is able to leverage additional resources from other partners that support projects. Second, spending creates work, generates tax revenues, and stimulates economic activity as wages and purchases flow through the economy. Together these impacts are known as the “multiplier effect.” This report focuses on the effects of PFW and Coastal program‐related spending on projects completed in fiscal year 2011 to provide an example of the economic impacts of the Programs. This report does not address many other aspects of the PFW and Coastal Programs that improve human welfare, such as ecological services, improved recreational opportunities, land acquisition, in‐kind contributions, or the effect of open space on land values.