Quantifying the Response of an Estuarine Nekton Community to Coastal Wetland Habitat Restoration

Globally coastal habitats are experiencing degradation and threatening the production of critical ecosystem services such as shoreline stabilization, water filtration, and nursery grounds for marine fauna. To combat the loss of these ecosystem services, resource managers are actively restoring coastal habitats. This study compares samples collected from non-restored sites, sites restored in 2011, and sites that underwent restoration in 2019. Restoration sites are impacted wetlands with high elevation mounds that were leveled to increase the areal extent of intertidal habitats, enabling the recruitment of intertidal flora and fauna. Fyke nets were used to sample nekton within the upper intertidal zone. To quantify restoration success, nekton abundance, biomass, diversity, and indicator species were quantified. Sites restored in 2011 had a greater abundance compared to non-restored sites. Common snook, clown gobies, silversides, juvenile mullet, and Gulf killifishes were indicator species at successfully restored sites, while salinity, site type, and Secchi depth played important roles in predicting abundance and diversity. These findings are consistent with recent studies suggesting it can take years to see quantifiable differences in nekton communities following habitat restoration. Additionally, this work provides new insight regarding the benefits of restoring coastal wetland elevation to maximize intertidal habitat, thereby positively impacting nekton communities.

Sediment Exchange Between the Created Saltmarshes of Living Shorelines and Adjacent Submersed Aquatic Vegetation in the Chesapeake Bay

Rising sea levels and the increased frequency of extreme events put coastal communities at serious risk. In response, shoreline armoring for stabilization has been widespread. However, this solution does not take the ecological aspects of the coasts into account. The “living shoreline” technique includes coastal ecology by incorporating natural habitat features, such as saltmarshes, into shoreline stabilization. However, the impacts of living shorelines on adjacent benthic communities, such as submersed aquatic vegetation (SAV), are not yet clear. In particular, while both marshes and SAV trap the sediment necessary for their resilience to environmental change, the synergies between the communities are not well-understood. To help quantify the ecological and protective (shoreline stabilization) aspects of living shorelines, we presented modeling results using the Delft3D-SWAN system on sediment transport between the created saltmarshes of the living shorelines and adjacent SAV in a subestuary of Chesapeake Bay. We used a double numerical approach to primarily validate deposition measurements made in the field and to further quantify the sediment balance between the two vegetation communities using an idealized model. This model used the same numerical domain with different wave heights, periods, and basin slopes and includes the presence of rip-rap, which is often used together with marsh plantings in living shorelines, to look at the influences of artificial structures on the sediment exchange between the plant communities. The results of this study indicated lower shear stress, lower erosion rates, and higher deposition rates within the SAV bed compared with the scenario with the marsh only, which helped stabilize bottom sediments by making the sediment balance positive in case of moderate wave climate (deposition within the two vegetations higher than the sediment loss). The presence of rip-rap resulted in a positive sediment balance, especially in the case of extreme events, where sediment balance was magnified. Overall, this study concluded that SAV helps stabilize bed level and shoreline, and rip-rap works better with extreme conditions, demonstrating how the right combination of natural and built solutions can work well in terms of ecology and coastal protection.

Technical and Social Approaches to Study Shoreline Change of Kuakata, Bangladesh

In recent years, shoreline determination has become an issue of increasing importance and concern, especially at the local level, as sea level continues to rise. This study identifies the rates of absolute and net erosion, accretion, and shoreline stabilization along the coast of Kuakata, a vulnerable coastal region in south-central Bangladesh. Shoreline change was detected by applying remote sensing and geographic information system (RS-GIS)-based techniques by using Landsat Thematic Mapper (TM), Landsat 8 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) satellite images at 30-m resolution from 1989, 2003, 2010, and 2020. The band combination (BC) method was used to extract the shoreline (i.e., land-water boundary) due to its improved accuracy over other methods for matching with the existing shoreline position. This study also used participatory rural appraisal (PRA) tools which revealed the societal impacts caused by the shoreline changes. Coupling RS-GIS and PRA techniques provides an enhanced understanding of shoreline change and its impacts because PRA enriches the RS-GIS outcomes by contextualizing the findings. Results show that from 1989 to 2020, a total of 13.59 km2 of coastal land was eroded, and 3.27 km2 of land was accreted, suggesting that land is retreating at about 0.32 km2 yr–1. Results from the PRA tools support this finding and demonstrate that fisheries and tourism are affected by the shoreline change. These results are important in Kuakata, a major tourist spot in Bangladesh, because of the impacts on fisheries, recreation, resource extraction, land use planning, and coastal risk management.

Evaluation of Lime-Treated Lateritic Soil for Reservoir Shoreline Stabilization

Sedimentation is one of the major problems addressed by reservoir management, and requires extensive effort to control it. This paper aims to evaluate the efficiency of the soil–lime stabilization technique for reservoir shores. The treatment consisted of spraying hydrated lime in slurry form over the surface of a lateritic clay sample with 1, 2, and 4% lime solution and curing times of 1, 7, 28, and 56 days with air-drying and moist-room storage. In addition, a single test with less than 1% lime solution by weight percentage was carried out. The post-cured specimens were mapped with SEM and X-ray analyses. A wave flume test was performed in samples subjected to diverse conditions of lime content, type, and curing time. The results showed that the present technique produces a Ca-rich crust by carbonation rather than stabilizing it and that the lime content and type of curing generate improvements in soil loss reduction, but the curing time does not. The technique gave relative protection against water level variation and wave impacts, but it is necessary to consider a frequent application of lime on the lateritic soil.

Best Fitting Methods for The Mud Profile Equations

In order to understand the dynamics of shoreline changes due to natural and anthropogenic causes, it is imperative for a coastal manager to comprehend the shore profile characteristics which are dependent on the sediment-wave interaction and can be depicted in a profile equation. Moreover, it is possible to derive the power form for the profile equation of a sandy coast based on the argument of wave energy dissipation per unit bed area and unit time. By using this same argument and considering the phenomenon that the main cause of wave damping over a muddy coast is due to energy absorption by the soft mud bottom, the mud profile equation can also be formulated. The aim of this study was to observe the mud profile equation geometry using best fitting method and to compare the characteristic features of the mud profiles using the field observation data. Shore profile data were measured from the muddy coast of Pantai Cermin in the eastern coast of North Sumatera Province. The data obtained were fitted to both the sand and mud profile equations. The procedures and results of the two best fitting methods, the nonlinear regression and the least square based trial and error search, were exhibited and compared. Several noteworthy features of the mud profile equation were found to be the same with the sand profile equation in describing the profile data. In order to provide a better profile and shoreline stabilization, it is recommended to use more complete observation data and good knowledge of shore profile by the coastal manager.

A Homeowner’s Guide to the Living Shoreline Permit Exemption Part 2: United States Army Corps of Engineers

Living shorelines are coastal shoreline stabilization interventions that rely on natural elements such as native vegetation and oyster reefs to protect property. The US Army Corps of Engineers, among other entities, regulates the placement of living shorelines through a permitting process to ensure project activities do not conflict with the public interest. In this 9-page guide, authors Savanna Barry, Sara Martin, and Eric Sparks provide you with example text for each application section that you can adapt to your needs to assist you in filling out the permit application. Published by the UF/IFAS Florida Sea Grant College Program. http://edis.ifas.ufl.edu/sg189

A Homeowner’s Guide to the Living Shoreline Permit Exemption Part 1: Florida Department of Environmental Protection

“Living shoreline” is a term that describes coastal shoreline stabilization interventions that rely on natural elements such as native vegetation and oyster reefs to protect property. Living shorelines typically involve construction or placement of materials within state waters (public lands that occur waterward of the mean high tide line). The Florida Department of Environmental Protection and other entities regulate the placement of living shorelines through a permitting process to ensure project activities do not conflict with the public interest. To streamline the approval process for environmentally beneficial projects such as living shorelines, the DEP has defined an exemption for small-scale living shoreline projects that meet certain criteria. This 17-page fact sheet written by Savanna Barry, Sara Martin, and Eric Sparks and published by the UF/IFAS Florida Sea Grant College Program provides a guide to completing the exemption forms. http://edis.ifas.ufl.edu/sg187 Updated August 2020 to include information about updated Department of Environmental Protection form.

FOCUS ON ECOLOGICAL IMPROVEMENTS IN THE DESIGN OF A BEACH STABILIZATION PROJECT

Baird harnessed the latest technology to improve the beach while minimizing environmental impacts and improving habitat wherever possible at a west coast location in Barbados. Baird used an Echoscope to precisely map bathymetry, living reef, and voids in relic reef. Following numerical and physical modeling, underwater structures for beach stabilization were specifically designed to accommodate coral transplants and lab grown corals. This first phase of shoreline stabilization creates new opportunities for enhancement, training, and education. Subsequent monitoring of biodiversity will measure the rate of reef recovery. Turbidity monitoring, as well as rainfall and surface run-off rates, will provide much needed information regarding the relative impacts of wave sediment resuspension and surface run-off on coral health.

WAVE ATTENUATION AND SEDIMENT TRANSPORT MONITORING OF LIVING SHORELINES IN THE DELAWARE BAY, U.S.

Living shorelines are considered a more natural approach to shoreline stabilization for low-energy coastlines in contrast to traditional “hard” shoreline armoring methods (i.e. bulkheads). Living shorelines often vary by design and materials, which are optimized for site-specific coastal and environmental conditions, such as wave climate, tidal range, sunlight exposure, etc.; however, the core benefits of all engineered living shorelines are typically the same: reduce shoreline erosion; enhance marine, intertidal, or backshore habitat; and increase resiliency to storm surge and/or sea level rise. While the general benefits of living shorelines are well known, project-specific technical data (i.e. percent of wave energy attenuation, shoreline advancement rates) documenting the effectiveness of living shorelines is more sparse. Moreover, monitoring equipment and analysis techniques required to capture the fine-detailed technical data can prove to be cost and/or labor intensive.