Search

Salt Marshes are a coastal ecosystem which have numerous benefits as coastal defense such as wave attenuation and can adapt to sea level rise. Wave flume tests, using a scale model of a cross-section of a salt marsh adjacent to a dike, were conducted in the Hydraulic Laboratory, to quantify the effectiveness of such a salt marsh system as flood defense (part of the Living Dikes research program). This thesis focuses on the reduction in wave run-up due to salt marshes on the adjacent dike, with a focus on high water levels. The wave run-up was measured using video processing, using a newly created algorithm to track the water movement on the dike slope. The results show a significant reduction in wave run-up due to wave attenuation over the salt marsh, further dependent on the presence of vegetation and the water depth on top of the salt marsh. The measured wave run-up values show some differences with values acquired using the TAW/EurOtop wave run-up formula. There is a correlation found with the wave steepness, where waves with a lower wave steepness do match the equation, and show a larger deviation for increasingly higher wave steepnesses., Civil Engineering | Hydraulic Engineering

Salt marshes are dynamic systems characterized by rapid and intense fluctuations in temperature. Because of this, the ectotherms residing in these environments must possess the ability to tolerate thermally variable environments. Mounting these plastic thermal responses requires energy and nutrients, which are acquired through diet. As the nutritional landscape shifts within these highly variable environments, it is critical we examine the modulating effect of diet on the capacity of ectotherms to respond to thermal variability. Using the California Killifish (F. parvipinnis), we tested the influence of fluctuating temperatures and diet quality on cardiac thermal performance through three specific hypotheses: (1) static acclimation temperature will yield a narrower thermal breadth when compared to fluctuating acclimation temperatures, (2) broad diets will yield higher cardiac thermal tolerance compared to a single-item diet and (3) upper thermal limits will vary when tested at the peak vs trough of a fluctuating acclimation cycle. F. parvipinnis were acclimated for 3 weeks at one of five ecologically relevant temperature regimes (11°C, 11-20°C, 20°C, 20-29°C, 29°C) while providing either a single-item diet or broad diet. Cardiac thermal tolerance was measured using an Arrhenius Breakpoint Temperature test. Both maximum heart rate and cardiac upper thermal limits increased with increasing acclimation temperature. Surprisingly, diet quality had a greater influence on cardiac thermal performance at colder fluctuating acclimations when compared to warmer fluctuating acclimations. Lastly, F. parvipinnis were found to exhibit rapid diel plasticity by altering thermal limits throughout a diurnal phase. This work suggests that both diet and fluctuating acclimations influence species’ upper thermal limits and outlines a clear need to incorporate more ecologically relevant temperature acclimations in lab-based research.

Habitat loss is one of the main threats to global biodiversity and ecosystem services. Human development, resource extraction, and climate change all contribute to the degradation or loss of ecosystems worldwide and in California. To counter these impacts, development may be regulated by following a general mitigation hierarchy where the priority is to first avoid injury to natural resources, then minimize remaining impacts, and finally, compensate for any unavoidable losses. This last step, known as compensatory mitigation, can offset environmental impacts through the restoration, enhancement, preservation, or creation (i.e., establishment) of habitat. My research focuses on three aspects of this process: the quantification of impacts to habitat, the cumulative effects of the permitted development, and strategies to improve outcomes of restoration projects. In Chapter 1, I review the cumulative impacts of development permitted by the California Coastal Commission between 2010 and 2018. Wetland habitat was the most frequently impacted, and mitigation usually took the form of restoration and was predominantly on-site and in-kind. I also provide recommendations for improving the compensatory mitigation process. In Chapter 2, I review metrics and tools that quantify impacts to seagrasses, kelps, and other macroalgae. I provide a list and chart to identify tools and applications best suited for ecological valuation and equivalency analysis for mitigation. In Chapter 3, I demonstrate restoration actions that can establish cover and survivorship of a dominant species at a restored tidal marsh in central California. Irrigation and larger plants provided the most cost-effective strategies in the short-term, when compensatory mitigation projects are likely to be held to performance standards. The topics of this thesis are varied but all relate back to the process of compensatory mitigation, the goal of which is to ensure the persistence of natural resources for present and f

Salt marshes are a valuable ecosystem with coastal protection potential, for example by absorbing hydrodynamic energy, increasing sedimentation and stabilizing the soil. This study investigated biomechanical properties of Spartina anglica to improve future models of wave-vegetation interaction. To fully understand the correlations between hydro- and biomechanics, the biomechanical vegetation properties from December 2021 to July 2022 are investigated with specimens collected from the field monthly. 551 specimens were used to determine the vegetation properties during storm surge season with high hydrodynamic forces. Additional geometrical properties were determined for 1265 specimens. Three-point bending tests measured the stiffness S (N/mm) and maximum forces Fmax (N). Different phenological states were observed over time and separated for analysis. These states provide a novel classification of growth periods for evaluating the coastal protection potential of Spartina anglica. Especially during storm season, most specimen were identified as broken shoots with a mean stiffness of 1.92N/mm (using 304 samples) compared to the bottom part of flowering shoots in December and January with a mean stiffness of 2.98N/mm (using 61 samples). The classification of plant properties recognizing phenological differences, based on plant state and seasonality, can be used to explain and reduce variability of biomechanical properties obtained during field campaigns. Additionally, this study shows that March to April is recommended for future investigations focusing on shoot properties during storm surge season, which is the important season for coastal engineers considering vegetation state.

Galician Rias are among the most productive ecosystems in the world. Consequently, the soils of their salt marshes and sediments of the intertidal flats show high organic matter contents, reactive Fe, and sulfate, which promote pyrite synthesis and accumulation, using sulfate for organic matter decomposition. This work studies the morphological variability and concentration of pyrites (individual crystals and framboids) in different geochemical environments found in the Ria de Ortigueira (salt marsh soils and bottom sediments in the inner, middle, and outer section), addressing their dynamics in the marsh-ria system in relation to the hydrodynamic characteristics defined by tides and river discharges. Framboidal pyrites were the dominant morphology in marsh soils and sediments in the middle and inner sections of the Ria, while isolated crystals dominated its outer section. The results showed that lower marsh soils (colonized by Spartina) are the most favorable environment for pyrite synthesis, showing high pyritic Fe concentrations and high degrees of pyritization, largely exceeding the values observed in sediments from Galician Rias and from most sedimentary environments worldwide. However, the amount of framboidal pyrites present in the lower marsh (SPE: 4–5 × 104 framboids) was clearly lower than in bottom sediments of the inner and middle part of the Ria de Ortigueira (∼2–7 × 106 framboids), mainly due to the fact that pyrites were found to form large framboids in lower salt marsh soils. Thus, the amount of framboidal pyrites does not seem to be a good indicator of redox conditions in modern marine sediments. Pyrite crystals found in the sediments of the Ria showed poorly defined vertices and facets, indicating their degradation and suggesting that a significant amount of the pyrites found in the middle and inner sections derive from marsh collapse. Finally, the output of framboidal pyrites towards the outer Ria de Ortigueira reflects the low intensity of residu

A rise in the global mean temperature induced by climate change is expected to have a large impact on ecosystems in all regions of the world. One of the threats is accelerated sea level rise (SLR). This may induce the loss of intertidal areas in tidal inlet systems. The long-term morphological response of tidal inlet systems can be modelled using reduced complexity model ASMITA (Aggregated Scale Morphological Interaction between Tidal inlets and the Adjacent coast). The ASMITA model simulates morphological development on an aggregated spatial and temporal scale by imposing a morphological equilibrium condition. As such the model is fast, allowing for multiple long-term simulations. The model is physics-based and the parameters can be related to field values. Currently, salt marshes are not implemented in ASMITA. However, salt marshes could be of importance to the morphological development in tidal inlet systems. Moreover, it is relevant to assess the resilience of the ecologically important salt marshes by themselves. The aim of this research is to implement salt marshes in ASMITA to assess their influence on the rest of the tidal inlet system and to gain insight into the long-term morphological response of salt marshes to accelerated SLR. Salt marsh development is governed by horizontal and vertical processes. The marsh height increases by capturing mineral sediment and by the accumulation of plant biomass. Autocompaction and deep subsidence lead to a decrease in marsh height. The implementation of salt marshes in ASMITA relies solely on the input of mineral sediment. At the marsh edge, generally, a cyclic behaviour of sedimentation and cliff erosion occurs. Due to the high degree of spatial aggregation, cliff erosion is excluded from the model extension. The governing processes for salt marsh development in the ASMITA model extension are mineral sedimentation, sediment availability and relative SLR. The spatial and temporal aggregatio, Civil Engineering

Dataset of published paper Elschot, K., Baptist, M., van Puijenbroek, M.E.B. (2023) Biocompacting livestock accelerate drowning of tidal salt marshes with sea level rise. Frontiers in Marine Science. Datasets included: 1. Final dataset on sedimentation and vegetation measurement in the field 2. Dataset of the model outcome for the different sea level rise scenario and suspended sediment supply.

The present study collated data on the Indian blue carbon repository (mangroves, seagrasses, and salt marshes) from peer-reviewed literature on carbon stock assessment. This meta-analysis indicated that the blue carbon ecosystems of India could have a collective carbon stock of 67.35 Tg C (mangroves, seagrass, and salt marsh accounting for 67 Tg C, 0.0630 Tg C, and 0.0049 Tg C, respectively). Several studies have ubiquitously measured the spatial extent of mangroves (~ 4991 km2) and seagrasses (~ 517 km2) in India; however, the salt marshes (290–1398 km2) have contradictions in estimates. The green payments against the blue carbon ecosystems of India can be as high as ~ 9.6 billion US $, whereas the social cost of carbon sequestered by these ecosystems can vary between 0.47 and 5.43 billion US $. The present study also identified the key research areas that require priority to minimize the uncertainties in blue carbon stock assessment to foster a robust ecosystem-based approach for climate change adaptation in the country. The study identified that less than half of the total mangrove habitats of India are yet to be sampled leaving a scope of substantial uncertainty in nationwide blue carbon estimates. The spatial extent of India’s salt marshes is another aspect that needs to be delineated with a higher confidence level. © 2022, The Author(s), under exclusive licence to Springer Japan KK, part of Springer Nature.

Considering the overexploitation of fishing on most of the world coasts, the ingestion of fish and shellfish will depend mostly on aquaculture production. Since intensive mariculture usually involves environmental impact, developing sustainable cultures is a priority. In this sense, salt marshes can provide ecosystem services and incorporate both conservation and extensive aquaculture activities. In the present study we compared gilthead seabream Sparus aurata Linnaeus, 1758 cultured in extensive and semi-intensive marsh ponds with wild conspecifics from surrounding coastal areas, using trophic characterization (diet analysis and stable isotopes) and trace metal accumulation. Stomach content analysis revealed different feeding habits among gilthead seabream from different origin. Although wild specimens had the most diverse diet, results of stable isotopes showed that extensive diet had the wider isotopic niche and revealed the highest similarities between wild and extensively cultured gilthead seabream. A similar trace element signature was also measured in wild and extensive culture, whereas the semi-intensive culture showed different concentrations for several elements. Cr, Fe and Mn showed the highest concentrations in semi-intensive cultured fish, while As and Zn showed the lowest values in this group. In any case, average values measured in both extensive and semi-intensive culture were, in general terms, below the hazardous limits provided by the standards recommended for trace metals by national and international regulations. Therefore, marsh ponds provide a suitable environment where the cultured fish, especially extensive, should be promoted.

Considering the overexploitation of fishing on most of the world coasts, the ingestion of fish and shellfish will depend mostly on aquaculture production. Since intensive mariculture usually involves environmental impact, developing sustainable cultures is a priority. In this sense, salt marshes can provide ecosystem services and incorporate both conservation and extensive aquaculture activities. In the present study we compared gilthead seabream Sparus aurata Linnaeus, 1758 cultured in extensive and semi-intensive marsh ponds with wild conspecifics from surrounding coastal areas, using trophic characterization (diet analysis and stable isotopes) and trace metal accumulation. Stomach content analysis revealed different feeding habits among gilthead seabream from different origin. Although wild specimens had the most diverse diet, results of stable isotopes showed that extensive diet had the wider isotopic niche and revealed the highest similarities between wild and extensively cultured gilthead seabream. A similar trace element signature was also measured in wild and extensive culture, whereas the semi-intensive culture showed different concentrations for several elements. Cr, Fe and Mn showed the highest concentrations in semi-intensive cultured fish, while As and Zn showed the lowest values in this group. In any case, average values measured in both extensive and semi-intensive culture were, in general terms, below the hazardous limits provided by the standards recommended for trace metals by national and international regulations. Therefore, marsh ponds provide a suitable environment where the cultured fish, especially extensive, should be promoted.

Salt marshes can contribute to coastal protection, but the magnitude of the protection depends on the width of the marsh. The cross-shore width of the marsh is to a large extent determined by the delicate balance between seaward expansion and landward retreat. The influence of the magnitude of daily occurring mild weather conditions and sediment availability on the variability of salt marsh width has not been systematically assessed. This paper investigates how the magnitude of homogeneous hydrodynamic forcing, combined with sediment availability, affects the biophysical development, and more specifically retreat and expansion of salt marshes. The dynamic extent of the salt marsh is assessed by modeling online-coupled hydrodynamics, morphodynamics and vegetation growth using the numerical Delft3D-Flexible Mesh model, and a vegetation growth module. Simulated patterns around the salt marsh edge resembled field observations, as well as the simulated temporal variability of the lateral position of the salt marsh edge. In the model, the salt marsh extended seaward at low wave forcing (0.00 m; 0.05 m), and retreated landward at higher wave forcing (0.10 m; 0.15 m). With increasing physical stress, the salt marsh edge was found at lower elevations, indicating an unhealthy system with a retreating marsh edge due to vegetation mortality, whereas decreasing physical stresses result in a higher salt marsh edge, enabling expansion. This balance suggests the importance of response time of vegetation to physical stress. Yet, the salt marsh forced with higher waves was able to switch from a retreating extent retrogradational to an expansional behavior as sediment supply increased., Environmental Fluid Mechanics

Vegetated coastal and marine habitats in the Nordic region include salt marshes, eelgrass meadows and, in particular, brown macroalgae (kelp forests and rockweed beds). Such habitats contribute to storage of organic carbon (Blue Carbon - BC) and support coastal protection, biodiversity and water quality. Protection and restoration of these habitats therefore have the potential to deliver climate change mitigation and co-benefits. Here we present the existing knowledge on Nordic BC habitats in terms of habitat area, C-stocks and sequestration rates, co-benefits, policies and management status to inspire a coherent Nordic BC roadmap. The area extent of BC habitats in the region is incompletely assessed, but available information sums up to 1,440 km(2) salt marshes, 1,861 (potentially 2,735) km(2) seagrass meadows, and 16,532 km(2) (potentially 130,735 km(2), including coarse Greenland estimates) brown macroalgae, yielding a total of 19,833 (potentially 134,910) km(2). Saltmarshes and seagrass meadows have experienced major declines over the past century, while macroalgal trends are more diverse. Based on limited salt marsh data, sediment C-stocks average 3,311 g C-org m(-2) (top 40-100 cm) and sequestration rates average 142 g C-org m(-2) yr(-1). Eelgrass C-stocks average 2,414 g C-org m(-2) (top 25 cm) and initial data for sequestration rates range 5-33 g C-org m(-2), quantified for one Greenland site and one short term restoration. For Nordic brown macroalgae, peer-reviewed estimates of sediment C-stock and sequestration are lacking. Overall, the review reveals substantial Nordic BC-stocks, but highlights that evidence is still insufficient to provide a robust estimate of all Nordic BC-stocks and sequestration rates. Needed are better quantification of habitat area, C-stocks and fluxes, particularly for macroalgae, as well as identification of target areas for BC management. The review also points to directives and regulations protecting Nordic marine vegetation, an, Climate change mitigation capacity of the Baltic coastal seascape: identification of hotspot environments for coastal blue carbonsequestration and guidance for sustainable management of the Baltic coastal landscapes under global change (CLIM-SCAPE)

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Eagle, M. J., Kroeger, K. D., Spivak, A. C., Wang, F., Tang, J., Abdul-Aziz, O. I., Ishtiaq, K. S., O’Keefe Suttles, J., & Mann, A. G. Soil carbon consequences of historic hydrologic impairment and recent restoration in coastal wetlands. The Science of the Total Environment, 848, (2022): 157682, https://doi.org/10.1016/j.scitotenv.2022.157682., Coastal wetlands provide key ecosystem services, including substantial long-term storage of atmospheric CO2 in soil organic carbon pools. This accumulation of soil organic matter is a vital component of elevation gain in coastal wetlands responding to sea-level rise. Anthropogenic activities that alter coastal wetland function through disruption of tidal exchange and wetland water levels are ubiquitous. This study assesses soil vertical accretion and organic carbon accretion across five coastal wetlands that experienced over a century of impounded hydrology, followed by restoration of tidal exchange 5 to 14 years prior to sampling. Nearby marshes that never experienced tidal impoundment served as controls with natural hydrology to assess the impact of impoundment and restoration. Dated soil cores indicate that elevation gain and carbon storage were suppressed 30–70 % during impoundment, accounting for the majority of elevation deficit between impacted and natural sites. Only one site had substantial subsidence, likely due to oxidation of soil organic matter. Vertical and carbon accretion gains were achieved at all restored sites, with carbon burial increasing from 96 ± 33 to 197 ± 64 g C m−2 y−1. The site with subsidence was able to accrete at double the rate (13 ± 5.6 mm y−1) of the natural complement, due predominantly to organic matter accumulation rather than mineral deposition, indicating these ecosystems are capable of large dynamic responses to restoration when conditions are optimized for vegetation growth. Hydrologic restoration enhanced elevation resilience and climate benefits of these coastal wetlands., This project was supported by the U.S. Geological Survey Coastal and Marine Hazards and Resources Program and the USGS Land Change Science Program's LandCarbon program, NOAA National Estuarine Research Reserve Science Collaborative NA14NOS4190145, and MIT Sea Grant 2015-R/RC-141. Contributions of Abdul-Aziz were also supported by NSF CBET Environmental Sustainability Award No. 1705941. Our stakeholder partners, including the Cape Cod National Seashore, Waquoit Bay National Estuarine Research Reserve, and the Bringing Wetlands to Market project team, and Towns and Conservation Commissions, including Eastham, Barnstable, Brewster, Yarmouth, Denis, Sandwich and Orleans, were instrumental in providing research support and site access.

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Baranes, H., Woodruff, J., Geyer, W., Yellen, B., Richardson, J. & Griswold, F. Sources, mechanisms, and timescales of sediment delivery to a New England salt marsh. Journal of Geophysical Research: Earth Surface, 127, (2022): e2021JF006478, https://doi.org/10.1029/2021jf006478., he availability and delivery of an external clastic sediment source is a key factor in determining salt marsh resilience to future sea level rise. However, information on sources, mechanisms, and timescales of sediment delivery are lacking, particularly for wave-protected mesotidal estuaries. Here we show that marine sediment mobilized and delivered during coastal storms is a primary source to the North and South Rivers, a mesotidal bar-built estuary in a small river system impacted by frequent, moderate-intensity storms that is typical to New England (United States). On the marsh platform, deposition rates, clastic content, and dilution of fluvially-sourced contaminated sediment by marine material all increase down-estuary toward the inlet, consistent with a predominantly marine-derived sediment source. Marsh clastic deposition rates are also highest in the storm season. We observe that periods of elevated turbidity in channels and over the marsh are concurrent with storm surge and high wave activity offshore, rather than with high river discharge. Flood tide turbidity also exceeds ebb tide turbidity during storm events. Timescales of storm-driven marine sediment delivery range from 2.5 days to 2 weeks, depending on location within the estuary; therefore the phasing of storm surge and waves with the spring-neap cycle determines how effectively post-event suspended sediment is delivered to the marsh platform. This study reveals that sediment supply and the associated resilience of New England mesotidal salt marshes involves the interplay of coastal and estuarine processes, underscoring the importance of looking both up- and downstream to identify key drivers of environmental change., The project described in this publication was in part supported by Grant or Cooperative Agreement No. G20AC00071 from the U.S. Geological Survey and a Department of Interior Northeast Climate Adaptation Science Center graduate fellowship awarded to H.E.B (G12AC00001).

© The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Castagno, K., Ganju, N., Beck, M., Bowden, A., & Scyphers, S. How much marsh restoration is enough to deliver wave attenuation coastal protection benefits? Frontiers in Marine Science, 8, (2022): 756670, https://doi.org/10.3389/fmars.2021.756670., As coastal communities grow more vulnerable to sea-level rise and increased storminess, communities have turned to nature-based solutions to bolster coastal resilience and protection. Marshes have significant wave attenuation properties and can play an important role in coastal protection for many communities. Many restoration projects seek to maximize this ecosystem service but how much marsh restoration is enough to deliver measurable coastal protection benefits is still unknown. This question is critical to guiding assessments of cost effectiveness and for funding, implementation, and optimizing of marsh restoration for risk reduction projects. This study uses SWAN model simulations to determine empirical relationships between wave attenuation and marsh vegetation. The model runs consider several different common marsh morphologies (including systems with channels, ponds, and fringing mudflats), vegetation placement, and simulated storm intensity. Up to a 95% reduction in wave energy is seen at as low as 50% vegetation cover. Although these empirical relationships between vegetative cover and wave attenuation provide essential insight for marsh restoration, it is also important to factor in lifespan estimates of restored marshes when making overall restoration decisions. The results of this study are important for coastal practitioners and managers seeking performance goals and metrics for marsh restoration, enhancement, and creation.

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemical Oceanography at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2022., Coastal ecosystems provide key services that benefit human wellbeing yet are undergoing rapid degradation due to natural and anthropogenic pressures. This thesis seeks to understand how disturbances impact salt marsh and estuarine ecosystem functioning in order to refine their role in coastal ecosystem service delivery and predict future resilience. Salt marsh survival relative to sealevel rise increasingly relies on the accumulation and preservation of soil organic carbon (SOC). Firstly, I characterized SOC development and turnover in a New England salt marsh and found that salt marsh soils typically store marsh grass-derived compounds that are reworked over centuries-to-millennia. Next, I assessed how two common marsh disturbances – natural ponding and anthropogenic mosquito ditching – affect salt marsh carbon cycling and storage. Salt marsh ponds deepen through soil erosion and decomposition of long-buried marsh peat. Further, the SOC lost during pond development is not fully recouped once drained ponds are revegetated and virtually indistinguishable from the surrounding marsh. Mosquito ditches, which were installed in ~ 90% of New England salt marshes during the Great Depression, did not significantly alter marsh carbon storage. In Buzzards Bay, Massachusetts, a US National Estuary, we tested relationships among measures of estuarine water quality, recreational activity, and local socioeconomic conditions to understand how the benefits of cultural ecosystem services are affected by shifts in water quality associated with global change and anthropogenic activity. Over a 24-year period, water quality degradation coinciding with increases in Chlorophyll a is associated with declines in fishery abundance and cultural ecosystem service values ($0.08 – 0.67 million USD). In combination, incorporation of both anthropogenic and natural disturbances to coastal ecosystem functioning and service delivery can produce improved estimates of ecosystem service valuation for eff, Funding for this work was provided by John D. and Catherine T. MacArthur Foundation (Grant no. 14-106159-000-CFP), National Science Foundation (OCE1233678), National Oceanic and Atmospheric Administration, National Oceanic and Atmospheric Administration – National Estuaries Research Reserve Collaborative (NA14OAR4170104 and NA- 14NOS4190145), Woods Hole Sea Grant (NA14OAR4170104), MIT Sea Grant (subaward number 5710004045), Ocean Ventures Fund, the Marine Policy Center Johnson Endowment, and Woods Hole Oceanographic Institution.

Dataset: Salt Marsh Water Exchange-Water, Surface and porewater salinity, radium/thorium radionuclide measurements, and nitrogen oxide concentration measurements. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/869708, NSF Division of Ocean Sciences (NSF OCE) OCE-1559274

Halophyte species growing under stressful conditions, such as the annual species of the Salicornia genus, have been recognized as a source of metabolites of pharmacological and nutraceutical interest. Therefore, planning the extraction of individual plants from wild populations in a sustainable way is especially important in the case of annual species. We studied the environmental matrix and population dynamic of four Salicornia ramosissima populations growing at two elevations in salt pans under a Mediterranean climate. In elevated areas, S. ramosissima populations presented maximum plant densities of between 628–6288 plants m−2 that remained almost constant until fruiting. In contrast, populations in depressed zones presented five-times greater soil-seed-bank densities and maximum plant densities than populations in elevated zones. In this context, populations in depressed zones lost c. 60% of their maximum plant densities from the end of spring and through summer. In whatever way the environmental matrix seemed to control the population dynamic of S. ramosissima in depressed zones, the effects of a stressful environment would interact with plant densities. In this sense, we recorded the density-dependent mortality for the densest population (max. 51,558 plants m−2). Our results are useful for planning a sustainable harvesting of natural populations of S. ramosissima.

The analysis of soil-vegetation interactions in erosion processes along coastlines requires accurate information about various factors influencing the upper soil layer. Yet, some of these parameters were previously determined by simplified, often hand held devices, and these were often biased by the skill and experience of the operator. This study thus investigates the erosion resistance of salt marsh soils influenced by grazing conditions for providing crucial findings for policy making and land management decisions; to that end, we present and use a novel shear resistance measuring device. This measuring device, called DiCoastar, was developed with a controllable step-motor and now allows us for the first time the determination of time histories of shear resistance by repeatable in-situ measurements, gaining information about the interaction between soil and root systems. A field study was conducted in salt marshes at Cäciliengroden and at Sönke-Nissen-Koog, both foreland salt marshes at the German North Sea coast. The two sites had been chosen due to their difference in grazing intensities, featuring semi-natural/ungrazed, moderately grazed and intensively grazed salt marshes. This was to enable the investigation of influences on soil shear strength and vegetation cover. Measurements of shear resistance were conducted with the DiCoastar in the chosen sites in the vicinity of the dike toes; it is found that the new device now provides consistent and repeatable measurements, irrespective of the operator, and only based on the pre-set control parameters. Results of the field study demonstrate that a marked increase of shear strength is only found in sites with high intensity grazing, but this is accompanied by a strong reduction in the vegetation cover and plant diversity, especially with regard to the vertical density distribution of the vegetation cover. As the reduction in vegetation cover leads to reduced wave attenuation over salt marshes and increased flow vel

The Cheadle Center at UCSB manages the North Campus Open Space (NCOS), which is a project that has restored 136 acres of upland and wetland habitats that existed before the area was converted into the Ocean Meadows Golf Course in the 1960s. The NCOS restoration project began in 2017 with a fine-scale grading of the site in order to recreate the salt marsh and use the excavated soil to rebuild the upland habitats to the southwest, which are now called the NCOS Mesa. In addition to re-establishing native biodiversity, a key goal of the restoration is to utilize the site as an educational, scientific, and recreational resource. This archived version of the August 2022 newsletter includes updates on snowy plover (Charadrius nivosus) breeding and fledging, snake biodiversity, a coverboard study of reptiles and other small animals, and the success of Ventura Marsh Milk-vetch (Astragalus pycnostachyus var. lanosissimus). The feature story focuses on Environmental DNA (eDNA) biodiversity monitoring. Community photos include Anna's and Allen’s Hummingbirds (Calypte anna and Selasphorus sasin), and Red-necked Phalarope (Phalaropus lobatus).

Ribbed mussels, Geukensia demissa, are marsh fauna that are used in coastal management and restoration due to the ecosystem services they provide. Ribbed mussel restoration efforts may be improved with a greater understanding of the environmental drivers of ribbed mussel distribution at multiple spatial scales to predict areas where restoration could be successful. This study sought to estimate the effects of within-marsh (4 m) and landscape (500 m) factors on ribbed mussel distribution. Ribbed mussel densities were surveyed at 11 sites along the coast of Georgia, USA, and overlaid with spatial data for within-marsh factors (elevation, distance to marsh features, slope) as well as landscape factors (percent cover by subtidal creek, forest, and development within a 500-m radius). The distribution model was then validated using three previously unsurveyed marshes and explained 55% of the variance in ribbed mussel abundance. Ribbed mussel abundances and occupancy were most sensitive to changes in within-marsh factors (elevation and distance to subtidal creeks, bodies of water inundated during the full tidal cycle) but were also sensitive to landscape features (percent landcover of forests and development). The highest ribbed mussel densities were found in mid-elevation areas (similar to 0.7 m NAVD88), far from subtidal creeks, and in marshes surrounded with forest and development. These results contrast with distributions in the northeastern USA, where ribbed mussels are distributed along subtidal creek banks. This work suggests that restoration may be most effective when focused on appropriate elevations and at locations away from the marsh-creek ecotone.

Data & Scripts featured in Fivash et al. 2021, ‘Can we enhance ecosystem-based coastal defense by connecting oysters to marsh edges? Analyzing the limits of oyster reef establishment’ in Ecological Engineering., Data & Scripts featured in Fivash et al. 2021, ‘Can we enhance ecosystem-based coastal defense by connecting oysters to marsh edges? Analyzing the limits of oyster reef establishment’ in Ecological Engineering. These files include the raw data (.csv, .jpg) and scripts (.r) used to create each figure in the manuscript, organized per figure (Figures 1 - 8, & S1-S2, .tif, .clip). The original published manuscript (.pdf) is included as well. For a complete description, see the 'README.txt'

Soil organic carbon (SOC) in coastal wetlands, also known as "blue C," is an essential component of the global C cycles. To gain a detailed insight into blue C storage and controlling factors, we studied 142 sites across ca. 5000 km of coastal wetlands, covering temperate, subtropical, and tropical climates in China. The wetlands represented six vegetation types (Phragmites australis, mixed of P. australis and Suaeda, single Suaeda, Spartina alterniflora, mangrove [Kandelia obovata and Avicennia marina], tidal flat) and three vegetation types invaded by S. alterniflora (P. australis, K. obovata, A. marina). Our results revealed large spatial heterogeneity in SOC density of the top 1-m ranging 40-200 Mg C ha(-1), with higher values in mid-latitude regions (25-30 degrees N) compared with those in both low- (20 degrees N) and high-latitude (38-40 degrees N) regions. Vegetation type influenced SOC density, with P. australis and S. alterniflora having the largest SOC density, followed by mangrove, mixed P. australis and Suaeda, single Suaeda and tidal flat. SOC density increased by 6.25 Mg ha(-1) following S. alterniflora invasion into P. australis community but decreased by 28.56 and 8.17 Mg ha(-1) following invasion into K. obovata and A. marina communities. Based on field measurements and published literature, we calculated a total inventory of 57 x 10(6) Mg C in the top 1-m soil across China's coastal wetlands. Edaphic variables controlled SOC content, with soil chemical properties explaining the largest variance in SOC content. Climate did not control SOC content but had a strong interactive effect with edaphic variables. Plant biomass and quality traits were a minor contributor in regulating SOC content, highlighting the importance of quantity and quality of OC inputs and the balance between production and degradation within the coastal wetlands. These findings provide new insights into blue C stabilization mechanisms and sequestration capacity in coastal wetlands.

Salt marshes are an integral part of coastal ecosystems that are changing rapidly with sea level rise (SLR). Because marshes provide important ecosystem services, such as carbon sequestration and shoreline protection, it is critical to understand how their economic benefit values are likely to be affected by SLR. Such change, however, depends on the capacity of marshes to adapt to flooding by migrating inland. This study provides the economic value of changes in carbon and non-carbon benefits using predicted changes in salt marsh coverage in Narragansett Bay, Rhode Island under three SLR scenarios and two marsh adaptation conditions. We apply regional carbon prices and a value function transfer approach to value other salt marsh service values. Results indicate an average annual value of $1,863/acre for carbon and $2,537/acre for non-carbon ecosystem services. This yields a mean discounted value of $592 million (M) (+14% compared to no change) over 90 years. We discuss alternative management strategies to enhance marshes’ capacity to migrate inland, which may accrue as much as $659 M.

Many Holocene estuaries were infilled to form convergent, single-channel systems, while others remained partially or wholly unfilled. This difference in the degree of infilling depends partly on the balance between fluvial and coastal sediment input and the hydrodynamics that can export sediment. However, it remains unclear to what degree this balance is tipped by mud supply and eco-engineering vegetation, and by what planform patterns the infilling proceeds. This study aims to explore experimentally how mud and vegetation change the degree and process of infilling, elevate and merge bars above intertidal levels and affect the planform of estuaries. To this end, three experiments were conducted in the Metronome, a flume that tilts periodically to create tidal currents, wherein forced tidal asymmetry resulted in net importing estuaries. In the second and third experiments, mud was supplied and in the third experiment seedlings were released of three vegetation species with eco-engineering traits at a laboratory scale. With only sand, the estuary fills sufficiently to form a multi-channel pattern with intertidal bars. Both mud and vegetation settle on intertidal bars and on the fluvial bay-head delta, thereby contributing to bar stabilization and further estuary infilling, pointing at effective strategies to keep up with future sea-level rise. This reduces channel mobility and effectively narrows the summed subtidal channel width toward an ideally converging funnel shape. This seems especially effective where vegetation stabilizes the mud. The experiments suggest that a range of steady states exists between the end-members of an unfilled and a completely infilled, ideal estuary.

Salt marshes are unique habitats between sea or saline lakes and land that need to be conserved from the effects of global change. Understanding the variation in functional structure of plant community along environmental gradients is critical to predict the response of plant communities to ongoing environmental changes. We evaluated the changes in the functional structure of halophytic communities along soil gradients including salinity, in Iranian salt marshes; Lake Urmia, Lake Meyghan, Musa estuary, and Nayband Bay (Iran). We established 48 plots from 16 sites in four salt marshes and sampled 10 leaves per species to measure leaf functional traits. Five soil samples were sampled from each plot and 30 variables were analyzed. We examined the changes in the functional structure of plant communities (i.e., functional diversity [FD] and community weighted mean [CWM]) along local soil gradients using linear mixed effect models. Our results showed that FD and CWM of leaf thickness tended to increase with salinity, while those indices related to leaf shape decreased following soil potassium content. Our results suggest that the variations in functional structure of plant communities along local soil gradients reveal the effect of different ecological processes (e.g., niche differentiation related to the habitat heterogeneity) that drive the assembly of halophytic plant communities in SW Asian salt marshes.

In many systems there has been extensive loss of foundation species and associated ecosystem services over the past century, as human alterations have increased. This is particularly true in temperate estuaries, where the main foundation species—salt marsh, seagrasses and oysters, have been in a state of decline. As restoration and conservation efforts increase, there is a critical need to better understand factors that affect the recovery of estuarine foundation species, as well as to characterize the consequences of such recovery. My dissertation research examines drivers and consequences of loss and recovery in two foundation species in Elkhorn Slough, a highly impacted estuary in Central California.In Chapters 1 and 2, I explore the role of a prolific crab species as both a consumer and ecosystem engineer in marsh ecosystems. I focus on vulnerable marsh edges prone to marsh loss; tidal creek bank edges (Ch. 1) and salt pannes. (Ch. 2). In Chapter 1, I show that crab grazing and the engineering of extensive burrow networks has a negative effect on marsh biomass, and this combined effect compromises the ability of the marsh to stabilize sediments, prevent erosion, and accrete and track sea level rise. In Chapter 2, I show that the rate of marsh recovery and panne contraction is driven by both physical and biological drivers. In Chapter 3, I conducted two small-scale experimental seagrass restorations and tracked structural and functional recovery. I detected astonishingly rapid expansion of restored plots and a related increase in associated ecosystem services such as biodiversity and improvement of water quality. Unlike other foundation species (corals, mangroves, redwood forests), seagrasses are fast-growing and I have demonstrated the rapidity of restoration success and a trajectory of multifunctional recovery.My work highlights how estuary management can be improved by investigations grounded in experimental field ecology, because they increase our understandi

The Montecito debris flows of 9 January 2018 deposited sediment along many portions of the Santa Barbara coast, including Carpinteria Salt Marsh Reserve. Since disturbances have the potential to impact the ecosystem services and functions that wetlands provide, an understanding of how the ecosystem at Carpinteria Salt Marsh Reserve responded to this disturbance is important to its ongoing management. However, a lack of opportunity to collect field data around the time of disturbance makes this task difficult to complete by field methods. To address this gap, Sentinel-2 imagery from four dates (November 2017, January 2018, November 2018, November 2020) was used to calculate landcover fractions, normalized difference vegetation index (NDVI), and modified anthocyanin reflectance index (mARI) and used in tandem with random forest classification to produce maps of landcover before, during, and after the debris flow. Post-classification change detection was then performed on the classified maps to track changes in landcover through time. Results from the random forest classification showed that NDVI and green vegetation fractions were the most important variables in classifying landcover, though this varied on a date-by-date basis; error matrices indicated that the model had high accuracy with values of 0.994, 0.920, 0.956. and 0.963 for the respective dates. Change detection shows a pattern of returning to pre-debris flow vegetation extent in the marsh. While total vegetated area experienced little change (0.12% increase), there was a change in the extent of vegetation type with high marsh vegetation shifting to mid marsh vegetation in regions near where increases in bare soil landcover occurred. These results show that disturbance due to debris flow can cause vegetation changes which may affect ecosystem function, such as decrease primary productivity and marsh resilience to further disturbance, that will need to be taken into consideration when managing depositional ev

The article presents the study’s results on the consolidation and afforestation of dune sands underlain by saline soil in Turtkul forestry enterprise desert zone of the Republic of Karakalpakstan and Khorezm forestry enterprise. Experimental work was carried out to consolidate and afforestation the windward dune slopes by installing mechanical protection from reed with planting along them seedlings of black saxaul, Paletsky cherkez. The main goal of the work was to flatten the upper unsecured part of the dune, sand the salt marsh in order to create protective forest cultures from psammophyte shrubs on them

Invasive alien plant species impart considerable impacts that contribute to the decline of biodiversity worldwide. The ability of an invasive species to overcome barriers to establish and spread in new environments, and the long-term effects of plant invasions supporting their persistence are keys to invasion success. The capacity of introduced species to form soil seed banks can contribute to their invasiveness, yet few studies of invaders have addressed seed bank dynamics. Improved knowledge of this recruitment process can improve conservation management. We studied temporal and spatial changes in soil seed bank characteristics of the cordgrass Spartina densiflora from two continental invaded ranges. In the Odiel Marshes (Southwest Iberian Peninsula), S. densiflora formed transient seed banks (<1 year). At Humboldt Bay Estuary (California), viable seeds persisted for at least 4 years though the germination percentage fell abruptly after the first year from 29 % to less than 5 % of remaining viable seeds. Total soil seed bank density increased with S. densiflora above-ground cover in both estuaries, pointing to the transient component of the seed bank as a critical component of vegetation dynamics during S. densiflora invasion. Even so, seed densities as high as c. 750 seeds m-2 in Odiel Marshes and c. 12 400 seeds m-2 in Humboldt Bay were recorded in some plots without fruiting S. densiflora plants. S. densiflora spikelet (dispersal unit) density was more than double close to the sediment surface than deeper within soil. Our study shows the importance of evaluating seed banks during the design of invasive species management since seed bank persistence may vary among invaded sites, and can affect the timing and duration required for desired management outcomes.

Ecosystems across the United States are changing in complex and surprising ways. Ongoing demand for critical ecosystem services requires an understanding of the populations and communities in these ecosystems in the future. This paper represents a synthesis effort of the U.S. National Science Foundation-funded Long-Term Ecological Research (LTER) network addressing the core research area of "populations and communities." The objective of this effort was to show the importance of long-term data collection and experiments for addressing the hardest questions in scientific ecology that have significant implications for environmental policy and management. Each LTER site developed at least one compelling case study about what their site could look like in 50-100 yr as human and environmental drivers influencing specific ecosystems change. As the case studies were prepared, five themes emerged, and the studies were grouped into papers in this LTER Futures Special Feature addressing state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the "connectivity" theme and has examples from the Phoenix (urban), Niwot Ridge (alpine tundra), McMurdo Dry Valleys (polar desert), Plum Island (coastal), Santa Barbara Coastal (coastal), and Jornada (arid grassland and shrubland) sites. Connectivity has multiple dimensions, ranging from multi-scalar interactions in space to complex interactions over time that govern the transport of materials and the distribution and movement of organisms. The case studies presented here range widely, showing how land-use legacies interact with climate to alter the structure and function of arid ecosystems and flows of resources and organisms in Antarctic polar desert, alpine, urban, and coastal marine ecosystems. Long-term ecological research demonstrates that connectivity can, in some circumstances, sustain valuable ecosystem functions, such as the persistence of foundation species and their associated biodiversi

Embankments are one of the key aspects of flood protection programs. As the sea levels are expected to rise the coming decades coastal protection is becoming increasingly important. To better prepare for the future, increased understanding of embankment breaching is desired. An area of embankment breaching that has been relatively left untouched is the impact of a foreland during a breaching event. This study examines the different effects caused by the presence of a foreland, namely reduced flow rate through the breach, limited breach growth and an elliptical erosion pattern in the foreland. Embankments are generally more erodible than forelands, and erosion of the foreland occurs after the adjacent embankment has been breached to its base level. As water continuous to flow over the foreland, a plunging jet will form, falling from the high foreland into the breach bottom. This causes undermining in the foreland and subsequent headcut erosion. A distinction is made between cohesive and non-cohesive forelands. Cohesive soil layers experience rotational failure and non-cohesive layers experience sliding failure. A model is presented that calculates headcut erosion in a foreland, flow characteristics over the foreland and erosion shape of the foreland. The erosion shape of the foreland affects the discharge through the breach and is captured in the non-dimensional constant m. The presented model is implemented as a module into the existing breaching model BRES. The added functionality will increase the accuracy BRES model results. Two experiments were performed to verify the model. The first experiment examined soil failure of a foreland in dry conditions by pushing an extracted foreland soil layer from a table to observe the failure type and the effects of vegetation on the strength of the soil. The second experiment was performed in collaboration with the University of Antwerp. A soil layer was extracted from a foreland and placed in a large flume. The, Civil Engineering

Conservation and restoration of salt marsh ecosystems are becoming increasingly important because of the many ecosystem services they provide. However, the processes controlling salt marsh establishment and persistence, especially on bare tidal flats in muddy areas, remain unclear. As muddy sediments typically experience a restriction of soil drainage, we expect that a surface drainage relief due to a heterogeneity topography, as might occur on the edge of tidal channels, can facilitate the establishment of salt marsh vegetation on muddy tidal flats. By means of a manipulative field experiment, using “Mega-Marsh Organ” mesocosms, we investigated the impact of surface drainage and elevation relative to mean sea level on (1) the survival of Spartina anglica seedlings from three different age classes: 1-yr, 3-month, and 1-week; and (2) the growth performance of mature S. anglica marsh tussocks. S. anglica seedling survival, especially in the establishment phase, was positively affected by better surface drainage, increases of seedling age, and higher elevation relative to mean sea level. That is, the survival rate of S. anglica seedlings at the end of 6th week increased from 0% (at surface water undrained, 1-week, 0 cm elevation) to 94.44% (at surface water drained, 1-yr, 90 cm elevation). In contrast, surface drainage did not affect the performance of large S. anglica marsh tussocks, as only increased elevation relative to mean sea level was shown to affect S. anglica tussock growth in terms of plant height, shoot numbers, and dry biomass. Based on our findings, we proposed a conceptual model to understand how surface drainage-driven feedbacks in a heterogeneous topography may be reinforced to induce salt marsh establishment in muddy systems. Further testing of present hypothesized model would be beneficial for insights into salt marsh establishment on tidal mudflats., Hydraulic Engineering

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Molino, G. D., Defne, Z., Aretxabaleta, A. L., Ganju, N. K., & Carr, J. A. Quantifying slopes as a driver of forest to marsh conversion using geospatial techniques: application to Chesapeake Bay coastal-plain, United States. Frontiers in Environmental Science, 9, (2021): 616319, https://doi.org/10.3389/fenvs.2021.616319., Coastal salt marshes, which provide valuable ecosystem services such as flood mitigation and carbon sequestration, are threatened by rising sea level. In response, these ecosystems migrate landward, converting available upland into salt marsh. In the coastal-plain surrounding Chesapeake Bay, United States, conversion of coastal forest to salt marsh is well-documented and may offset salt marsh loss due to sea level rise, sediment deficits, and wave erosion. Land slope at the marsh-forest boundary is an important factor determining migration likelihood, however, the standard method of using field measurements to assess slope across the marsh-forest boundary is impractical on the scale of an estuary. Therefore, we developed a general slope quantification method that uses high resolution elevation data and a repurposed shoreline analysis tool to determine slope along the marsh-forest boundary for the entire Chesapeake Bay coastal-plain and find that less than 3% of transects have a slope value less than 1%; these low slope environments offer more favorable conditions for forest to marsh conversion. Then, we combine the bay-wide slope and elevation data with inundation modeling from Hurricane Isabel to determine likelihood of coastal forest conversion to salt marsh. This method can be applied to local and estuary-scale research to support management decisions regarding which upland forested areas are more critical to preserve as available space for marsh migration., Funding for this study was provided by the United States Geological Survey’s Coastal/Marine Hazards and Resources Program and Ecosystems Mission Area.

Data on sedimentation, sediment grain size, vegetation composition and vegetation characteristics of a field experiment on a salt marsh in nature reserve the Slufter (Wadden island Texel, the Netherlands).

Nature-based coastal defense schemes commonly value bivalve reefs for i) reducing coastal erosion in the intertidal and for ii) forming fringing reefs near salt marsh edges to protect them against lateral retreat. The capacity for a reef to reduce erosion increases at a higher position in the tidal frame as the lower over-lying water level magnifies the influence of the reef on wave attenuation. Unfortunately, ecological constraints on reef development typically limit their practical application in coastal protection schemes to the lower intertidal, as bivalves grow best with long inundation times. In micro-tidal areas this is a lesser problem, given the close proximity of lower and upper intertidal ecosystems in space. By contrast, in meso- and macro-tidal estuaries, bivalve reefs tend to form hundreds of meters away from existing marshes, nullifying any wave-protective benefits. In this study, we produce evidence that with the assistance of management measures, widespread reef formation is possible on open mudflats, including bordering the marsh edge in meso- and macro-tidal estuaries, where natural reef formation is normally strongly limited. In four locations throughout the meso- to macro-tidal Dutch Scheldt estuary, we observed the presence of individuals of two major intertidal reef-forming bivalves, Pacific oysters (Crassostrea gigas) and blue mussels (Mytilus edulis), within low-lying Spartina anglica-dominated marshes. As these communities lie well outside of the expected range of reef formation, this observation suggests the existence of mechanisms that extend the habitable range of these bivalves. In a series of field experiments, we first demonstrate how the stabilization of shell-substrate within the marsh promotes successful establishment and adult survival. Secondly, by placing artificial stable substrate in transects from the subtidal up to the marsh edge, we demonstrate that bivalve establishment is possible throughout a much larger range of the int

Biological invasions offer model systems of contemporary evolution. We examined trait differences and evolution across geographic clines among continents of the intertidal grass Spartina alterniflora within its invasive and native ranges. We sampled vegetative and reproductive traits in the field at 20 sites over 20° latitude in China (invasive range) and 28 sites over 17° in the US (native range). We grew both Chinese and US plants in a glasshouse common garden for 3 yr. Chinese plants were c. 15% taller, c. 10% denser, and set up to four times more seed than US plants in both the field and common garden. The common garden experiments showed a striking genetic cline of seven-fold greater seed set at higher latitudes in the introduced but not the native range. By contrast, there was a slight genetic cline in some vegetative traits in the native but not the introduced range. Our results are consistent with others showing that introduced plants can evolve rapidly in the new range. S. alterniflora has evolved different trait clines in the native and introduced ranges, showing the importance of phenotypic plasticity and genetic control of change during the invasion process.