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The Cheadle Center at UCSB manages more than 340 acres of open space between Ellwood Mesa and Goleta Slough, carrying out ecological restoration, research, and education projects at these sites. Characterized by a rich complex of oak woodland, coastal sage scrub, grassland, and wetland ecosystems, the area is known for its relatively high level of biodiversity. The Cheadle Center’s project sites and management areas serve to protect and strengthen the region’s ecology and ecosystems through habitat conservation, upland restoration, wetland creation and enhancement, and the implementation of sustainable stormwater management solutions. Through careful integration with local watersheds and surrounding natural areas, The Cheadle Center's management areas provide an important corridor and refuge for wildlife, ensure the long term preservation of the region's natural resources, and serve as outdoor classrooms, research sites, and recreational areas for the campus community and the public. This archived version of the March 2024 newsletter includes updates on the Ellwood Bioblitz, Spring weeding efforts, Wildflowers, Rare Plants, and the Ocean Meadows Housing Project. The feature story focuses on the presetations and research conducted at Cheadle Center management areas. Community photos include Lesser Scaup (Aythya affinis), Red-breasted Merganser (Mergus serrator), Caspian Tern (Hydroprogne caspia), and more!

Abstract: The future of coastal wetlands will depend on the combined effects of climate change and human impacts from urbanization and coastal management. Disentangling the effects of these factors is difficult, but satellite imagery archives provide a way to track biological and physical changes in wetlands over recent decades to reveal how coastal wetlands have been changing in response to climate and human drivers. In this study, we used Landsat to monitor the conditions of 32 coastal wetlands in southern California from 1984 to 2019 and identify environmental and human drivers of these trends. Wetland conditions were characterized by vegetation greenness, using the normalized difference vegetation index (NDVI), and by habitat composition, derived from areal estimates of wetland and subtidal habitats. Overall, wetlands displayed three types of long‐term response: greening and gaining wetland (10), greening and losing wetland (16), and browning and losing wetland (6). Regional environmental drivers with overall positive effects on wetland NDVI were sea level, wave height, and precipitation, whereas stream discharge, vapor pressure deficit, and air temperature had negative or nonlinear effects. Wetland area change was primarily correlated with sea level, but response was highly contextual among sites. Negative trends in wetland NDVI and area were more common in larger sites with low elevations and in sites with open inlets. Restoration had mixed effects, with only half of the restored sites showing positive changes in NDVI and wetland area post‐restoration. The important work of managing and restoring urban coastal wetlands is complicated by variability and context and requires us to account for the influence of humans and climate as we build a regional understanding of historic, present, and future wetland health.

The Cheadle Center at UCSB manages more than 340 acres of open space between Ellwood Mesa and Goleta Slough, carrying out ecological restoration, research, and education projects at these sites. Characterized by a rich complex of oak woodland, coastal sage scrub, grassland, and wetland ecosystems, the area is known for its relatively high level of biodiversity. The Cheadle Center’s project sites and management areas serve to protect and strengthen the region’s ecology and ecosystems through habitat conservation, upland restoration, wetland creation and enhancement, and the implementation of sustainable stormwater management solutions. Through careful integration with local watersheds and surrounding natural areas, The Cheadle Center's management areas provide an important corridor and refuge for wildlife, ensure the long term preservation of the region's natural resources, and serve as outdoor classrooms, research sites, and recreational areas for the campus community and the public. This archived version of the March 2024 newsletter includes updates on the NCOS Mesa burn area and Ventura Marsh Milk Vetch. The feature story focuses on the Sierra Madre restoration area. Community photos include Bonaparte's Gull (Chroicocephalus philadelphia), American Bittern (Botaurus lentiginosus), Orange-crowned Warbler (Vermivora celata) and more!

Abstract: Salt marshes exist at the terrestrial-marine interface, providing important ecosystem services such as nutrient cycling and carbon sequestration. Tidal inputs play a dominant role in salt marsh porewater mixing, and terrestrially derived freshwater inputs are increasingly recognized as important sources of water and solutes to intertidal wetlands. However, there remains a critical gap in understanding the role of freshwater inputs on salt marsh hydrology, and how this may impact marsh subsurface salinity and plant productivity. Here, we address this knowledge gap by examining the hydrologic behavior, porewater salinity, and pickleweed (Sarcocornia pacifica also known as Salicornia pacifica) plant productivity along a salt marsh transect in an estuary along the central coast of California. Through the installation of a suite of hydrometric sensors and routine porewater sampling and vegetation surveys, we sought to understand how seasonal changes in terrestrial freshwater inputs impact salt marsh ecohydrologic processes. We found that salt marsh porewater salinity, shallow subsurface saturation, and pickleweed productivity are closely coupled with elevated upland water level during the winter and spring, and more influenced by tidal inputs during the summer and fall. This seasonal response indicates a switch in salt marsh hydrologic connectivity with the terrestrial upland that impacts ecosystem functioning. Through elucidating the interannual impacts of drought on salt marsh hydrology, we found that the severity of drought and historical precipitation can impact contemporary hydrologic behavior and the duration and timing of the upland-marsh hydrologic connectivity. This implies that the sensitivity of salt marshes to climate change involves a complex interaction between sea level rise and freshwater inputs that vary at seasonal to interannual timescales.

The effects of grazing and browsing by terrestrial vertebrates are poorly understood for southern hemisphere saltmarshes, many of which are recovering from stock grazing. We investigated whether the native late-successional shrub, Tecticornia arbuscula, regenerating several years after the cessation of stock grazing, was grazed by wild herbivorous mammals to the degree of impeding recovery. We measured T. arbuscula growth parameters in exclosures and adjacent controls for two years and used camera trapping of animals across four consecutive austral seasons to indicate grazing pressure. Height growth was more affected by exclosure from grazing than lateral change. Notably, grazing did not prevent the recovery of the shrubs from stock grazing at either site, suggesting that the growth rate of T. arbuscula relative to total grazing pressure is at sustainable levels and these shrubs are in a trajectory of recovery, with the smaller plants growing the fastest. Also, we found little difference between our two sites in grazing impact, despite one site having twice the number of animals, largely native macropods, as the other site, which was dominated by introduced lagomorphs (rabbits and hares). These findings further the knowledge of native and non-native terrestrial vertebrates in austral saltmarsh ecology and conservation. [ABSTRACT FROM AUTHOR]

Parasites can alter the traits or densities of mutualistic partners, potentially destabilizing mutualistic associations that underpin the structure, functioning, and stability of entire ecosystems. Despite the potentially wide‐ranging consequences of such disruptions, no studies have directly manipulated parasite prevalence and/or intensity in a mutualistic partner, nor quantified the resulting community‐level effects. Here, we investigated the effects of a common trematode parasite (Cercaria opaca) on the strength of a keystone facultative mutualism in western Atlantic salt marshes between the foundational marsh cordgrass, Spartina alterniflora, and the ribbed mussel, Geukensia demissa. Cordgrass increases mussel survivorship and growth through shading, while mussels enhance cordgrass growth by producing nutrient‐rich biodeposits. This mutualistic association also creates conditions that enhance biodiversity and ecosystem functioning, and mediates the ability of foundational plants to resist and recover from extreme drought. We used lab and field assays to show how increasing infection with trematode metacercariae negatively influenced mussel biodeposit production, as well as the strength of mussel shells and byssal attachments. By conducting a field manipulation using experimentally infected mussels, we demonstrated that the mutualistic benefits of mussels to cordgrass growth decreased with increasing trematode infection intensity—a pattern likely generated by reduced mussel biodeposition and enhanced mortality. Additionally, increasing parasite loads in mussels led to predictable decreases in the abundances of benthic invertebrates, as well as in key ecosystem characteristics and process rates (i.e., redox potential and sediment accretion). Finally, a survey of five North Carolina salt marshes demonstrated that infection with C. opaca was most common in mussels in areas experiencing cordgrass die‐off due to drought, and that infection intensity decreased with distance from die‐off areas. Because the mussel–cordgrass mutualism underpins marsh ecosystem resilience to drought‐associated die‐off, our results suggest that parasitism may depress recovery from these disturbances. Although this is the first experimental demonstration of parasites indirectly altering community structure and functioning by undermining an ecologically influential mutualism, this type of relationship could be common in nature, given that parasites frequently infect influential mutualists. [ABSTRACT FROM AUTHOR]

Living shorelines (LS) stabilize eroding banks while providing more natural habitats and creating a gentler slope for enhanced migration of flora and fauna migration as sea levels rise. Typical LS practices include using several different materials, including oyster shell bags, to stabilize shorelines and planting marsh grasses. However, incorporating other important species interactions among marsh organisms can improve LS function and stability. For example, ribbed mussels, Guekensia demissa, benefit marsh plants by adding nutrients and stabilizing sediments. Unfortunately, mussels are not typically included in management and restoration practices. In this study, the objective was to investigate whether ribbed mussels facilitate marsh grass growth at a LS site in the southeastern US. We conducted field surveys for mussel abundance and recruitment, and a manipulative in situ experiment at an established LS site in Georgia to explore the impacts of adding mussels. Although mussel treatment did not have a significant effect on Spartina alterniflora metrics (i.e., density, height, biomass), Spartina plots with high mussel density exhibited ~300% increase in biomass relative to the start of the experiment, while plots without mussels only increased by ~100%. Some of the variability within treatments can be explained by high and sustained mussel mortality throughout the experimental period, likely due to predation, that impacted the actual mussel densities in our plots. We found that Spartina height, density, and biomass exhibited significant positive relationships with mussel biomass. Thus, ribbed mussels may be useful in living shorelines restoration projects if they are planted in sufficient densities, in aggregations, and/or with protective devices. [ABSTRACT FROM AUTHOR]

Sea-level rise (SLR) will produce unprecedented changes in tidal marsh systems that already cope with daily tidal fluctuation, disturbances from storms, and salinity changes from droughts and runoff events. Additionally, negative impacts from non-native invasive species may alter marsh plants' ability to respond to SLR stressors like increased inundation and salinity. Increasingly, tidal marsh communities must tolerate both changes in the physical environment from SLR and increased risk of invasion by non-native species. To assess the response of a threatened tidal marsh cordgrass (Spartina foliosa) to both stressors, we implemented a field experiment in San Francisco Bay, CA, USA, exposing cordgrass to a treatment that extended tidal inundation projected with SLR using a recently developed in situ method. At one of two field sites, we also enclosed the cordgrass with or without the invasive European green crab, Carcinus maenas. We found that cordgrass responded negatively to longer inundation, although these effects varied by site and year. In higher inundation treatments, cordgrass survival increased with increasing surface elevation of the plot. Cordgrass survival was lower in the presence of invasive green crabs relative to controls. We did not find interacting effects of responses to increased inundation and invasive species presence, which highlights the need to consider how latent or sequential effects of multiple stressors may affect ecosystems. This study demonstrates significant biological responses to invasive species presence and increased inundation. Evaluating relative effects and timing of multiple stressors, especially those induced by climate change and invasive species, will help us to manage threatened ecological communities in a changing world. [ABSTRACT FROM AUTHOR]

Coastal habitats are some of the most imperiled due to climate change and anthropogenic activities. As such, it is important to understand population dynamics of the species that may play a role in regulating coastal systems. Diamondback terrapins in Northwest Florida have been understudied, which has resulted in a gap in our knowledge for this region. To help fill this gap, we conducted a capture-mark-recapture study in St. Joseph Bay, Florida, from 2018 to 2021. Overall, we captured 518 individuals, including 146 recaptures, and we used several modeling frameworks to estimate apparent survival, recapture probability, population entrance, and population size. Our estimates of apparent survival were relatively low, especially for adult males (0.77) and adult females (0.83), but there is a considerable amount of uncertainty around our estimates. Our models indicated that the super-population consists of 1122 individuals (971–1327 95% CI), and the population is comprised of more adult males (753; 665–866 95% CI) than adult females (102; 85–130 95% CI) and juveniles (267; 221–331 95% CI). Estimates of population entrance varied by year throughout our study duration. This study is the first to document a Malaclemys terrapin population in this region of Florida, and we recommend long-term monitoring in order to gain inferences for the management of this declining coastal species. [ABSTRACT FROM AUTHOR]

Salinity is one of the main limiting factors driving the expansion of Spartina alterniflora by affecting plant functioning. Comparative studies of plant leaves, under 0 (T0), 5 (T5), 10 (T10), and 20 g/kg (T20) soil salinity, were carried out. Results showed that soil salinity significantly affected most leaf traits of S. alterniflora. Total and live leaf numbers first increased and then decreased with increasing soil salinity. Leaf morphology in T5 were substantially larger than another three treatments, and the ratio of leaf length to width considerably decreased with increasing soil salinity. As the soil salinity increased, leaf dry mass and leaf dry matter content (LDMC) displayed a pattern similar to total leaf number. Leaf mass traits indicated that while a more efficient nutrient conservation strategy was adopted in T10, S. alterniflora rapidly produced biomass in T0. Strong correlations were observed between leaf morphological and mass traits except for some parts of LDMC. The confidence ellipses of leaf traits indicated significant differences in leaf traits of the four treatments. We believe that insights into the aforementioned aspects can contribute to a better understanding of the responses of leaf traits of S. alterniflora and provide valuable information about its adaptation strategy. [ABSTRACT FROM AUTHOR]

Salt marshes in the southern North Sea are part of the UNESCO World Heritage Site, Wadden Sea, the largest unbroken system of intertidal sand and mud flats in the world. They provide a very high nature value while significantly contributing to coastal flood and erosion risk management as a nature-based element of flood and erosion risk management systems for densely populated coastal areas. Climate change-induced sea-level rise is a significant concern: an integrated approach to salt marsh management adapted to the effects of climate change necessitates an understanding of the impact of different management strategies. This review commences with a description of the biogeomorphological conditions and processes in salt marshes for a better understanding of the natural dynamics and how they are influenced by management and climate change. Next, the impact of salt marshes on hydrodynamic processes and their role as nature-based elements of flood and erosion risk management is presented; management options and implementation methods are discussed and analysed concerning coastal flood management and nature conservation requirements. In conclusion, targeted salt marsh management needs to consider the initial conditions and the development aims of the specific site are integrated into a conceptual framework. Salt marshes have the potential to adapt to sea-level rise, thereby contributing to the long-term protection of coastal areas. [ABSTRACT FROM AUTHOR]

Aim: Tidal marsh ecosystems are heavily impacted by human activities, highlighting a pressing need to address gaps in our knowledge of their distribution. To better understand the global distribution and changes in tidal marsh extent, and identify opportunities for their conservation and restoration, it is critical to develop a spatial knowledge base of their global occurrence. Here, we develop a globally consistent tidal marsh distribution map for the year 2020 at 10‐m resolution. Location: Global. Time period: 2020. Major taxa studied: Tidal marshes. Methods: To map the location of the world's tidal marshes at 10‐m resolution, we applied a random forest classification model to Earth observation data from the year 2020. We trained the classification model with a reference dataset developed to support distribution mapping of coastal ecosystems, and predicted the spatial distribution of tidal marshes between 60° N and 60° S. We validated the tidal marsh map using standard accuracy assessment methods, with our final map having an overall accuracy score of 0.85. Results: We estimate the global extent of tidal marshes in 2020 to be 52,880 km2 (95% CI: 32,030 to 59,780 km2) distributed across 120 countries and territories. Tidal marsh distribution is centred in temperate and Arctic regions, with nearly half of the global extent of tidal marshes occurring in the temperate Northern Atlantic (45%) region. At the national scale, over a third of the global extent (18,510 km2; CI: 11,200–20,900) occurs within the USA. Main conclusions: Our analysis provides the most detailed spatial data on global tidal marsh distribution to date and shows that tidal marshes occur in more countries and across a greater proportion of the world's coastline than previous mapping studies. Our map fills a major knowledge gap regarding the distribution of the world's coastal ecosystems and provides the baseline needed for measuring changes in tidal marsh extent and estimating their value in terms of ecosystem services. [ABSTRACT FROM AUTHOR]

The Cheadle Center at UCSB manages more than 340 acres of open space between Ellwood Mesa and Goleta Slough, carrying out ecological restoration, research, and education projects at these sites. Characterized by a rich complex of oak woodland, coastal sage scrub, grassland, and wetland ecosystems, the area is known for its relatively high level of biodiversity. The Cheadle Center’s project sites and management areas serve to protect and strengthen the region’s ecology and ecosystems through habitat conservation, upland restoration, wetland creation and enhancement, and the implementation of sustainable stormwater management solutions. Through careful integration with local watersheds and surrounding natural areas, The Cheadle Center's management areas provide an important corridor and refuge for wildlife, ensure the long term preservation of the region's natural resources, and serve as outdoor classrooms, research sites, and recreational areas for the campus community and the public. This archived version of the November 2023 newsletter includes updates on the Ellwood Marine Terminal restoration, rare plants sign, bulb planting, and Salt Marsh Bird's Beak. The feature story focuses on the Chumash cultural burn on the NCOS Mesa. Community photos include Eastern Kingbird (Tyrannus tyrannus), Sora (Porzana carolina), and Great Blue Heron (Ardea herodias).

The Stress Gradient Hypothesis predicts facilitation will become more important than competition where abiotic stress is high, and the framework successfully predicts positive interactions between species in many systems. Fewer studies have focused on intraspecific facilitation, and to our knowledge none examine intraspecific interactions in Pacific Coast salt marshes of North America. We used two species that tend to occur in large, monospecific patches to test for intraspecific facilitation in a restored California marsh, where tides and evaporation during summer create moisture and salinity gradients across elevation. We tested performance of Frankenia salina or Jaumea carnosa in restoration plots using two treatments: clustered plantings to promote facilitation, and widely spaced plantings to limit interaction between individuals. We characterized the soil water potential gradient and measured plant survival, cover, physiology, and susceptibility to herbivory across elevation and planting treatments. Soil water potential declined sharply with elevation, suggesting plant stress should be higher upslope. However, tissue water potential was unaffected by elevation, and survival was high—suggesting growing conditions remained benign. A seawater addition treatment did not alter the response of plants or plant interactions to the abiotic gradient. At 19 months, intraspecific competition prevailed across the entire elevation gradient for both species, with less transplant cover in clustered plantings. However, clustered Frankenia fared better during a transient period of heavy rabbit herbivory. Aside from this temporary benefit, clustering did not reduce stress and strongly suppressed growth—suggesting that restoration designs for the high marsh should minimize competition.

Question: In productive grasslands highly dominated by a single plant species, herbivores can promote overall plant diversity. Wild boars (Sus scrofa) often decrease species diversity, alter regeneration and change community composition in their native and invader ranges while digging and uprooting vegetation for feeding. In addition, wild guinea pigs (Cavia aperea), a small vertebrate herbivore native to South America, concentrate their feeding activities in open patches where they also affect plant diversity, biomass and composition. In this context, can wild‐boar disturbances promote plant diversity in herbaceous systems characterized by a highly dominant species? Can native wild guinea pigs magnify these impacts? Location: Coastal grasslands and salt marshes of the northeastern part of the temperate Argentine pampas, that are dominated by native or exotic herbaceous species. Methods: We first analyzed alpha‐ and beta‐diversity of plant assemblies in three natural coastal herbaceous areas, invaded by wild boars, through samplings (comparing disturbed and undisturbed areas) and experiments (using exclosures and control plots). Then, we analyzed whether wild guinea pigs could affect patch recovery (alpha‐ and beta‐diversity) after wild‐boar disturbances in one site. Results: Wild boars enhanced alpha‐diversity (compared to undisturbed areas) but had no significant effect on beta‐diversity. Nevertheless, wild guinea pigs feeding on wild‐boar disturbances increased between‐patch heterogeneity in species composition (i.e., beta‐diversity). Conclusion: Wild boars remove vegetation in patches that, without subsequent wild‐guinea‐pig herbivory, dominant species rapidly recover. Wild‐guinea‐pig herbivory allows different subordinate species to peak at different disturbed patches, contributing to larger species richness at larger scales in areas otherwise occupied by highly dominant plant species. In a wider context, these results imply that the joint action of different‐sized exotic and native herbivores can help to maintain plant species diversity in highly plant‐dominated grasslands. [ABSTRACT FROM AUTHOR]

Understanding how climate and local stressors interact is paramount for predicting future ecosystem structure. The effects of multiple stressors are often examined in small‐scale and short‐term field experiments, limiting understanding of the spatial and temporal generality of the findings. Using a 22‐year observational dataset of plant and grazer abundance in a southeastern US salt marsh, we analyzed how changes in drought and grazer density combined to affect plant biomass. We found: (1) increased drought severity and higher snail density both correlated with lower plant biomass; (2) drought and snail effects interacted additively; and, (3) snail effects had a threshold, with additive top‐down effects only occurring when snails were present at high densities. These results suggest that the emergence of multiple stressor effects can be density dependent, and they validate short‐term experimental evidence that consumers can augment environmental stress. These findings have important implications for predicting future ecosystem structure and managing natural ecosystems. [ABSTRACT FROM AUTHOR]

Thin layer sediment placement (TLP) is used to build elevation in marshes, counteracting effects of subsidence and sea level rise. However, TLP success may vary due to plant stress associated with reductions in nutrient availability and hydrologic flushing or through the creation of acid sulfate soils. This study examined the influence of sediment grain size and soil amendments on plant growth, soil and porewater characteristics, and greenhouse gas exchange for three key U.S. salt marsh plants: Spartina alterniflora (synonym Sporobolus alterniflorus), Spartina patens (synonym Sporobolus pumilus), and Salicornia pacifica. We found that bioavailable nitrogen concentrations (measured as extractable NH4+‐N) and porewater pH and salinity were inversely related to grain size, while soil redox was more reducing in finer sediments. This suggests that utilizing finer sediments in TLP projects will result in a more reduced environment with higher nutrient availability, while larger grain sized sediments will be better flushed and oxygenated. We further found that grain size had a significant effect on vegetation biomass allocation and rates of gas exchange, although these effects were species‐specific. We found that soil amendments (biochar and compost) did not subsidize plant growth but were associated with increases in soil respiration and methane emissions. Biochar amendments were additionally ineffective in ameliorating acid sulfate conditions. This study uncovers complex interactions between sediment type and vegetation, emphasizing the limitations of soil amendments. The findings aid restoration project managers in making informed decisions regarding sediment type, target vegetation, and soil amendments for successful TLP projects. [ABSTRACT FROM AUTHOR]

The Atlantic tarpon Megalops atlanticus is a tropical-subtropical fish that occupies mangrove and salt marsh habitats during the first year of life. Diet during the first few months of life can have substantial effects on growth and survival of fishes. The purpose of our study was to examine the diet of age-0 tarpon in the North Inlet-Winyah Bay estuarine system, located near the northern extent of their distribution in the western Atlantic Ocean. We examined stomach contents to characterize tarpon diet and relate tarpon feeding to water temperature. The most important prey items based on the frequency of occurrence and proportion by weight indices were small fishes and crustaceans, whereas copepods were the most important prey based on the proportion by number index. Small age-0 tarpon (≤ 100 mm) consumed small crustaceans (copepods) while large age-0 tarpon (> 100 mm) consumed larger crustaceans (shrimp) and age-0 tarpon of all sizes consumed fish. Most tarpon with empty stomachs were collected at temperatures < 25 °C, whereas most tarpon with prey in their stomach were collected at temperatures > 25 °C. The proportion of tarpon having at least one prey item in their stomach contents was greatest around 28 °C and declined at lower and higher water temperatures. Salt marsh habitats in the North Inlet-Winyah Bay estuarine system provide suitable food resources for age-0 tarpon. As water temperatures increase and tropical species, such as tarpon, expand their range, these coastal nursery habitats may become more important for tarpon growth and recruitment to the spawning stock. [ABSTRACT FROM AUTHOR]

Geologic reconstructions of overwash events can extend storm records beyond the brief instrumental record. However, the return periods of storms calculated from geologic records alone may underestimate the frequency of events given the preservation bias of geologic records. Here, we compare a geologic reconstruction of storm activity from a salt marsh in New Jersey to two neighboring instrumental records at the Sandy Hook and Battery tide gauges. Eight overwash deposits were identified within the marsh's stratigraphy by their fan‐shaped morphology and coarser mean grain size (3.6 ± 0.7 φ) compared to autochthonous sediments they were embedded in (5.6 ± 0.8 φ). We used an age–depth model based on modern chronohorizons and three radiocarbon dates to provide age constraints for the overwash deposits. Seven of the overwash deposits were attributed to historical storms, including the youngest overwash deposit from Hurricane Sandy in 2012. The four youngest overwash deposits overlap with instrumental records. In contrast, the Sandy Hook and Battery tide gauges recorded eight and 11 extreme water levels above the 10% annual expected probability (AEP) of exceedance level, respectively, between 1932/1920 and the present. The geologic record in northern New Jersey, therefore, has a 36–50% preservation potential of capturing extreme water levels above the 10% AEP level. [ABSTRACT FROM AUTHOR]

In salt marsh ecosystems, daggerblade grass shrimp, Palaemon (Palaemonetes) pugio, play a crucial role in food webs and serve as the definitive host for the bopyrid isopod Probopyrus pandalicola. These ectoparasites infest the branchial chambers of grass shrimp, which can lead to decreased energy availability and sterilization of infected hosts. Although bopyrid isopod infestation of daggerblade grass shrimp has been frequently reported in literature from coastal marshes of the southeastern United States, the prevalence of this parasite has not been recently documented in daggerblade grass shrimp from marshes of the northeastern United States. The goal of this project was to quantify the prevalence of Pr. pandalicola infestations in Pa. pugio across Cape Cod, Massachusetts. We evaluated bopyrid isopod prevalence from shrimp collected from 5 different salt marsh habitats along Cape Cod in August 2021. Bopyrid isopod infestations were found in shrimp at 4 of 5 salt marshes, with prevalence ranging from 0.04 to 14.1%. Seasonal resampling of one of the salt marshes revealed the highest average infestation prevalence in spring (<17.1%) and an isolated high of 30.3% prevalence in a single salt panne. A series of linear and multivariate models showed that panne area, shrimp abundance, and distance to shoreline were related to Pr. pandalicola shrimp infestations in salt pannes in summer. This study describes the prevalence of the bopyrid isopod infesting daggerblade grass shrimp in salt marshes in New England, with implications for how parasitized shrimp influence salt marsh food webs in which they are found. [ABSTRACT FROM AUTHOR]

Sporobolus alterniflorus (S. alterniflorus) is a widespread invasive plant that poses significant threats to coastal wetland ecosystems and local economies worldwide. However, most existing management methods for S. alterniflorus are costly and provide only temporary relief due to reoccurrences and reinvasion. Additionally, limited attention has been paid to examining the application of invasion mechanisms in the design of management measures, hindering the development of effective strategies. In this paper, we reviewed the literature on the mechanisms and management of S. alterniflorus invasion. We identified the key factors enabling invasion mechanisms, analyzed how they are targeted in current control methods, and pointed out their implications for future research. We recommend that the invasion mechanisms of S. alterniflorus should be comprehensively considered during the design of management measures. Furthermore, future research on invasion mechanisms could focus on the joint effects and the relative roles of individual factors in successful invasion, the impact of S. alterniflorus invasion on the coupled human and natural systems, and the systematic review of studies at different scales. [ABSTRACT FROM AUTHOR]

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In salt marshes of the Southeastern USA, purple marsh crabs (Sesarma reticulatum), hereafter Sesarma, aggregate in grazing and burrowing fronts at the heads of tidal creeks, accelerating creek incision into marsh platforms. We explored the effects of this keystone grazer and sediment engineer on salt marsh sediment accumulation, hydrology, and carbon (C) and nitrogen (N) turnover using radionuclides (210Pb and 7Be), total hydrolyzable amino acids (THAA), and C and N stable isotopes (δ13C and δ15N) in sediment from paired Sesarma-grazed and un-grazed creeks. Sesarma-grazed-creek sediments exhibited greater bioturbation and tidal inundation compared to sediments in un-grazed creeks, as indicated by larger 210Pb and 7Be inventories. Total organic carbon (TOC) to total nitrogen (TN) weight ratios (C:N) were higher and δ15N values were lower in grazed-creek sediments than in un-grazed-creek sediments, suggesting Sesarma remove and assimilate N in their tissues, and excrete N with lower δ15N values into sediments. In support of this inference, the percent total carbon (TC) and percent TOC declined by nearly half, percent TN decreased by ~ 80%, and the C:N ratio exhibited a ~ threefold increase between Sesarma fore-gut and hind-gut contents. An estimated 91% of Sesarma's diet was derived from Spartina alterniflora, the region's dominant salt marsh plant. We found that, as Sesarma grazing fronts progress across marsh landscapes, they enhance the decay of Spartina-derived organic matter and prolong marsh tidal inundation. These findings highlight the need to better account for the effects of keystone grazers and sediment engineers, like Sesarma, in estimates of the stability and size of blue C stores in coastal wetlands. [ABSTRACT FROM AUTHOR]

Tylorrhynchus osawai, nereidid polychaete that is considered to support estuarine biodiversity, undergoes a unique epitokous metamorphosis for reproductive swarming. The reproductive swarming of this species has been observed in Japan for more than 100 years; however, the benthic phase of this species has not been well researched. In this study, we aimed to elucidate the morphological allometry and life history, specifically the reproductive swarming, of this species. To accomplish this, surveys were conducted to collect atokes and epitokes from a tidal river in Kyushu, Japan. A total of 1670 T. osawai specimens were collected and preserved in 80% ethanol. The body widths of these specimens were measured, while several intact specimens underwent additional measurements of body length and the number of chaetigers. The morphological allometry of this species differed between atokous and epitokous forms, indicating that its heteronereis form might be suitable for migration from a tidal river to the ocean. The survey results pertaining to the benthic phase of this species indicated that its lifespan was approximately one year or longer. In addition, the settlement, growth, and maturity of this species exhibited a degree of plasticity, potentially influenced by habitat landscapes and sediment conditions. Based on the surveys conducted on reproductive swarming, climate change could have caused the peak of reproductive swarming to shift slightly later than that of several historical observations. Our findings contribute to elucidating the ecological significance of epitokous metamorphosis in nereidid polychaetes and to conserving T. osawai populations. [ABSTRACT FROM AUTHOR]

Context: Salt marsh landscapes at the land-sea interfaces exhibit contrasting spatiotemporal dynamics, resulting from varying physical constraints that limit new marsh establishment. The expansion of salt marsh landscapes towards the sea or their retreat towards the land is determined by patch-level changes, relying on the balance of power between the intrinsic biota traits and external physical disturbances. Objectives: Examine how marsh dynamics respond to physical constraints, and clarify the pathway from coupled physical processes involving hydrodynamic forces, sediment transport, and morphological changes to rapid patch evolution and landscape changes. Methods: We defined and distinguished four types of marsh changes based on patch proximities from five-month drone images in two typical marsh pioneer zones of the Yangtze Estuary, China: outlying expansion, edge expansion, infilling expansion, and retreat. Hydrodynamics and sediment transport were synchronously measured and compared near the two marsh edges, and morphological changes were generated by drone-derived digital elevation models (DEMs). Results: We identified distinct seasonal patterns of net marsh expansion at the accretion-prone site, that is: Net marsh expansion started from the outlying expansion in spring, followed by edge expansion in summer and infilling expansion in autumn. However, at the erosion-prone site that experienced high bed shear stress, low sediment availability and high seaward sediment transport, we only observed limited infilling and edge expansion in spring. This suggests that the potential for long-distance patch formation beyond the initial marsh edges is diminished in areas subjected to intensive physical disturbances. Conclusions: Patch evolution dynamics in response to site-specific physical constraints drive state differentiation of salt marsh landscape changes. Consequently, the heterogeneous evolution in salt marsh landscapes should be taken into account in restoration practice. [ABSTRACT FROM AUTHOR]

Tidal creeks play a crucial role in lateral transport of carbon and nutrients from tidal salt marshes. However, the specific impact of tidal creek development on carbon and nutrient distribution within the marsh remains poorly understood. The objective of this study is to assess the influence of lateral tidal flooding through the tidal creeks on the spatial distribution of carbon and nitrogen fractions in the soils of a Chinese temperate salt marsh. We conducted a comprehensive analysis of the relative variations in different carbon and nitrogen fractions, along with soil physicochemical and microbial indicators, between the bank soil of the tidal creek and its lateral inland soils across high, middle, and low flats. Our findings highlight that tidal creek development significantly affects the middle flat, leading to substantial variations in organic carbon and total nitrogen. The low flat mainly experiences changes in dissolved inorganic carbon levels. Furthermore, a lateral increase in microbial biomass is observed in the middle flat, indicating that the significantly lower SOC in the middle flat might be ascribed to enhanced microbial decomposition. The lateral enrichment of dissolved inorganic carbon in the low flat is possibly related to the nearshore location and/or abiotic adsorption in inorganic carbon sequestration. Overall, this study demonstrates the critical role of tidal creek development in shaping the distribution patterns of carbon and nitrogen fractions in tidal salt marshes. [ABSTRACT FROM AUTHOR]

Analyses of feeding patterns of fish assemblages, common approaches for understanding their habitat use and habitat dependence, have been conducted infrequently in Japanese estuarine salt marshes. The present study, based on gut content analyses, revealed the food habits of fishes occurring in salt marsh estuaries in high- and low-salinity rivers with different sediment conditions (sandy mud and muddy bottoms) in the western Seto Inland Sea, Japan. Ontogenetic changes in food preference were recognized in six species (Lateolabrax japonicus, Acanthogobius flavimanus, Glossogobius olivaceus, Platycephalus sp. 2, Acanthopagrus latus and Gymnogobius breunigii) out of 22 species examined, small individuals generally feeding on calanoid and harpacticoid copepods, and terrestrial and aquatic insects, but subsequently switching to other larger prey items (e.g., crabs, shrimps, and fishes) with growth. A cluster analysis based on dietary overlaps showed that the fish assemblages of the two salt marshes comprised nine trophic groups (zooplankton, small crustacean, large crustacean, polychaete, mollusk, fish, insect, detritus, and plant feeders), large crustacean feeders being the most abundant, followed by fish feeders, compared with polychaete and mollusk feeders, represented by only two and one species, respectively. The most important food items for the overall assemblage comprised shrimps, fishes and detritus, represented by high gut volumes in all fishes and high consumption frequencies. Furthermore, the trophic structures of fish assemblages and important food items varied between the rivers, polychaete and insect feeders being more abundant, with increasing the consumption of their main food items in the low-salinity and muddy river. Some fishes also showed remarkably different diets between adjacent rivers, highlighting small spatial scale variations in food-use patterns of fishes at the community and species levels in salt marsh estuaries. [ABSTRACT FROM AUTHOR]

The changes of soil moisture, salinity, and nutrients by halophyte colonization in high-salinity environment profoundly affect the assembly and structure of microbial communities. However, salt marshes in arid region have received little attention. This study was conducted in Lianhuachi Lake, a typical inland salt marsh wetland in China, to determine the physicochemical characteristics of salt crusts in [Kalidium cuspidatum (Ung.-Sternb.) Grub.] colonization areas and bulk soil, respectively, and to analyze the microbial community structure of salt crusts by high-throughput sequencing. Kalidium cuspidatum colonization significantly decreased total salinity, soil water content, and water-soluble ions of salt crusts and increased total carbon, total nitrogen, and total phosphorus content. At the same time, changes in physicochemical properties caused by Kalidium cuspidatum colonization affect the ecological processes of bacterial, fungal, and archaeal community assemblies in salt crusts. In addition, cross-kingdom network analysis showed that Kalidium cuspidatum colonization increased the complexity and stability of microbial networks in salt crust soils. Functional projections further showed that bacterial diversity had a potential driving effect on the nitrogen cycle function of salt crust. Our study further demonstrated the different ecological strategies of microorganisms for halophyte colonization in extreme environments and contributed to the understanding of restoration and management of salt marsh wetlands in arid region. [ABSTRACT FROM AUTHOR]

Expansion of drainage networks through the headward erosion of tidal creeks is an eco‐geomorphologic response of salt marshes to accelerated sea‐level rise (SLR). This response can counter the negative impacts of an elevation deficit by increasing drainage and encouraging plant health, thereby reducing potential for submergence and marsh platform loss. In the wetlands of Cape Romain, SC, intense bioturbation near creek heads by the common marsh crab Sesarma reticulatum has been found to facilitate sediment erosion and rapid creek growth. This keystone grazer has been recently observed to have increasing influence on landscape evolution throughout the southeast US coast. Here, we compare measurements taken at Sapelo Island, GA, with those previously collected at Cape Romain, to confirm that eco‐geomorphic feedbacks facilitating creek growth at each location are similar, and to compare these processes under differing background conditions. We use sediment cores, precise elevation measurements and historical imagery to compare substrate properties, elevation within the tidal frame, creek growth rates and drainage morphology at both sites. Our results show identical processes; however, the higher elevation of the marsh at Sapelo Island leads to shallower and shorter periods of tidal inundation, explaining the greater soil strength and lower belowground biomass compared with the marsh at Cape Romain. The smaller tidal range at the site in Cape Romain compared with Sapelo Island translates to a proportionally shallower depth of tidal creeks, which therefore requires less erosion to produce headward creek extension. These effects are likely to have contributed to slower growth rates of tidal creeks at Sapelo Island during the past several decades of SLR. Our findings highlight the similarities in process but differences in rates in how marshes are responding to climate‐related stress. [ABSTRACT FROM AUTHOR]

Salt marshes play an important role in coastal carbon cycling. Unfortunately, these systems are threatened by sea level rise. One strategy to increase the resilience of marshes is thin‐layer placement of sediment (TLP). While TLP can boost elevation, little is known about how TLP alters greenhouse gas fluxes. We addressed this knowledge gap by measuring greenhouse gas fluxes in TLP plots that received either 7 cm (TLP‐7 cm) or 14 cm of added sediment (TLP‐14 cm), control plots that received no sediment, and reference plots that served as elevation end goal targets for the TLP plots. We found that mean (± standard error) CO2 uptake was comparable between control and TLP plots (control: −25.84 ± 2.46; TLP‐7 cm: −24.44 ± 3.32; TLP‐14 cm: −23.18 ± 2.08 mmol m−2 hr−1) and significantly less in reference plots (−9.54 ± 2.98 mmol m−2 hr−1). However, TLP plots (TLP‐7 cm: 35.74 ± 12.70, TLP‐14 cm: 19.79 ± 3.47 μmol m−2 hr−1) emitted up to 7 to 22 times more CH4 compared to control (5.77 ± 0.74 μmol m−2 hr−1) and reference (1.63 ± 0.75 μmol m−2 hr−1) plots, respectively. N2O fluxes from the TLP plots exhibited both uptake (TLP‐7 cm) and emission (TLP‐ 14 cm). Overall, the marsh remained a net greenhouse gas sink, at least during the times we measured—during the day and throughout the growing season. This research demonstrates the dynamics of greenhouse gas fluxes in marshes amended with sediment and highlights the need for future diel and annual measurements. Plain Language Summary: Salt marshes are important ecosystems that play a key role in the global cycling and storage of carbon. However, although salt marshes store carbon they also emit other potent greenhouse gases such as methane and nitrous oxide. Currently there is uncertainty in the magnitude and variability of these fluxes. Further complicating this issue is the impact of sea level rise (SLR) and SLR adaptation strategies on greenhouse gas dynamics. This study explores the impact of sediment addition, a SLR adaption strategy where sediment is added to the surface of the marsh to boost elevation, on greenhouse gas fluxes. We found that sediment addition increased methane fluxes but that overall marsh areas amended with sediment still stored more greenhouse gases than they emitted. Key Points: CO2 uptake was comparable to control plots across all treatments of sediment additionCH4 emissions were 4–7 times higher in sediment addition plots compared to control plots, and up to 22 times higher compared to reference plotsN2O fluxes were low and variable and did not exhibit a consistent pattern with sediment addition [ABSTRACT FROM AUTHOR]

Observations that biodiversity—particularly in coastal marine species—is redistributing itself as the environment changes have been key indicators of the climate change era. Historical surveys help us identify such patterns in taxa that might not be typically monitored for distribution or abundance. As recently as 1992, the southern ribbed mussel Geukensia granosissima was considered to be relatively abundant in northeastern Florida. Climate velocity predictions might suggest that these mussels would now have cryptically invaded the marshes of Georgia, which has historically only harbored the congener Geukensia demissa, with possible ecosystem consequences. I resurveyed Geukensia from both coasts of Florida and sites in Georgia for mitochondrial and nuclear genomic diversity. As of this report, G. granosissima is all but gone from the Atlantic coast of Florida, though some signature of its history remains in these data. The reason for this rapid fluctuation in distribution is not known but is important for clarification of regional biogeographic patterns. [ABSTRACT FROM AUTHOR]

Xenassiminea nana n. gen. and n. sp. is described from estuaries of temperate mainland Japan (central to western Honshū, Shikoku and Kyūshū). This species has a minute, colourless, translucent, depressed and helicoid shell and resembles some so-called skeneimorphs. However, the anatomical characters of the head–foot, radula and reproductive system indicate that this species belongs to the Assimineidae, in spite of the dissimilarity in shell features. The presence of basal cusps of the central radular teeth and the extremely rudimentary cephalic tentacles indicate that it should be assigned to the subfamily Assimineinae. The shell size (0.8 mm in length, 1.1 mm in diameter) is the smallest among known assimineids. It lives beneath stones deeply buried in sandy mud flats at the innermost parts of large bays and can be regarded as threatened by the rapid loss of these habitats in recent years. [ABSTRACT FROM AUTHOR]

Salt marshes are globally important ecosystems and thus their resilience to climate change holds societal importance. To date, studies addressing salt marsh responses to climate change have focused on sea‐level rise and biogeochemical feedbacks with increasing inundation. Less is known about how salt marsh sediment temperatures, which impact physical, biological, and chemical ecosystem processes, will respond to climate change. In this study, we present multi‐depth sediment temperature and porewater level data from low‐, mid‐, and high‐marsh sites at a New England salt marsh for a 1‐year period and investigate how salt marsh sediment temperatures respond to atmospheric and oceanic forcing. We use spectral analyses to identify the frequencies at which sediment temperatures vary and link the temperature variations to specific forcing mechanisms. We find that all sites across the marsh responded to air temperature with roughly equal amplitude whereas the responses to radiative heating and ocean tides varied spatially. The high‐marsh site is more sensitive to radiative heating than the mid‐ and low‐marsh sites. The low‐marsh is affected by tidal processes and inundation whereas the high‐ and mid‐marsh sites are not. In addition, we find that the bulk thermal diffusivity of the saturated sediments decreases with distance from the tidal channel. These factors contribute to considerable temporal and spatial variability in sediment temperatures with elevation, distance from the tidal channel, and time of year (season) being most important. [ABSTRACT FROM AUTHOR]

The two‐way interactions between biological and physical processes, bio‐geomorphic feedback, play a vital role in landscape formation and evolution in salt marshes. Patchy vegetation represents a typical form of scale‐dependent feedback in salt marshes and is primarily responsible for the formation of efficient drainage networks. The intuitive manifestation of scale‐dependent feedback is the heterogeneity of flow and landscape. Process‐based modeling is an essential tool for exploring flow heterogeneity, but calculations for small spatial scales and over long time frames can be prohibitively costly. In this study, we proposed a deep learning model architecture, UNet‐Flow, based on convolutional neural networks (CNNs), which is used to build a surrogate model to simulate a flow field induced by salt marsh patchy vegetation. After optimizing and evaluating the model, we discovered that UNet‐Flow exhibits a speed improvement of over four orders of magnitude compared to single‐process simulations using the free surface flow model TELEMAC‐2D, with acceptable levels of error. Furthermore, we proposed an approach that combines the process‐based model SISYPHE with the deep learning method to model geomorphic heterogeneity. After numerous simulations of flow heterogeneity modeling using UNet‐Flow, we obtained a significant logarithmic relationship between scale‐dependent feedback strength and vegetation stem density, and an ascending‐descending trend in feedback strength was observed as the number or surface area of vegetation patches increased. Finally, we investigated the relationship between geomorphic heterogeneity and vegetation‐related variables. This study represents a noteworthy effort to study bio‐geomorphology using deep learning methods. Plain Language Summary: Bio‐geomorphic feedback refers to the two‐way interactions between biological and physical processes. It is a crucial factor in the formation and evolution of salt marsh landscapes. Vegetation patches are typically found at the front edge of salt marshes. These patches extensively influence the landscapes by influencing the flow, which induces the formation of efficient drainage channels. Due to the critical role vegetation patches play in the development of landscapes, numerical simulation of bio‐geomorphic feedback requires sub‐meter scale grid cells, thus resulting in high computational power needed for long‐term simulations. In this paper, we introduced a deep‐learning‐based model to simulate the flow heterogeneity induced by vegetation patches. Furthermore, we employed a hybrid approach combining process‐based modeling and deep learning to simulate geomorphic heterogeneity. The deep‐learning model is significantly faster than a traditional model with an overall acceptable error. After numerous simulations, we identified a significant logarithmic relationship between bio‐geomorphic feedback strength and vegetation density. Additionally, we observed noteworthy associations between geomorphic heterogeneity and patch distribution, vegetation stem density, and suspended sediment concentration. This finding highlights the model's potential importance in analyzing small‐scale bio‐geomorphic processes. Key Points: A deep learning architecture based on convolutional neural networks (CNNs) was introduced to model flow and geomorphic heterogeneityThe CNN‐based model significantly improves computational efficiency while maintaining an acceptable overall errorThe distribution of vegetation patches plays a crucial role in shaping the fundamental morphology of tidal creeks [ABSTRACT FROM AUTHOR]

The global warming-driven poleward expansion of mangrove habitats (e.g., Avicennia germinans and Rhizophora mangle) into temperate salt marshes (e.g., Spartina alterniflora and Juncus roemerianus) has been shown to alter coastal soil organic carbon (SOC) storage. However, the taxa-specific consequences of this vegetation shift on the origin and size of SOC sub-fractions (particulate OC (POC); mineral-associated OC (MAOC); and reactive iron-associated OC (FeR-MAOC)) remain largely unexplored. In this study, we used a particle size-based SOC fractionation method to compare quantity and δ13C composition of bulk and each SOC sub-fractions in soil cores collected from Apalachicola Bay barrier islands in Florida, USA, the highest latitude where monospecific communities of all four aforementioned plants co-occur. Depth-dependent variation of bulk soil δ13C clearly showed the global warming-driven replacement of S. alterniflora by mangroves, as well as reciprocal substitutions of S. alterniflora and J. roemerianus, probably driven by changes in wetland elevation. Higher OC burial rates in mangrove habitats suggested that mangrove soils were principally developed by particle deposition. In contrast, comparatively lower OC burial rates but higher OC stocks in salt marsh habitats illustrated subsurface OC input from salt marsh roots. POC was primarily derived from contemporary plant detritus; its concentration was higher in salt marsh habitats (58.8 ± 9.0 % of SOC) relative to mangroves (38.4 ± 6.0 % of SOC). In contrast, MAOC content did not vary across plant habitats (53.5 ± 10.9 % of SOC), and principally originated from microbially-transformed OC and pre-existing plants. FeR-MAOC was essentially absent in R. mangle soils (2.9 ± 3.6 % of SOC) while representing a minor fraction of MAOC in three other plant habitats (7.8 ± 7.0 % of SOC). The δ13C of FeR-MAOC was more like the present-day surface plants, highlighting the in situ FeR-MAOC formation in their active oxidizing rhizospheres.

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).

Abstract Background The study of soil organic carbon characteristics and its relationship with soil environment and vegetation types is of great significance to the evaluation of soil carbon sink provided by inland salt marshes. This paper reports the characteristics of soil organic carbon fractions in 0–50 cm soil layers at four vegetation communities of the Qinwangchuan salt marsh. Results (1) The soil organic carbon content of Phragmites australis community (9.60 ± 0.32 g/kg) was found to be higher than that of Salicornia europae (7.75 ± 0.18 g/kg) and Tamarix ramosissima (4.96 ± 0.18 g/kg) and Suaeda corniculata community (4.55 ± 0.11 g/kg). (2) The soil dissolved organic carbon, particulate organic carbon and soil microbial biomass carbon in 0–50 cm soil layer of Phragmites australis community were higher, which were 0.46 ± 0.01 g/kg, 2.81 ± 0.06 g/kg and 0.31 ± 0.01 g/kg, respectively. (3) Soil organic carbon was positively correlated with dissolved organic carbon, particulate organic carbon, and microbial biomass carbon, and negatively correlated with easily oxidized organic carbon. (4) Above-ground biomass has a strong direct positive effect on soil organic carbon, total nitrogen and pH have a strong direct positive effect on microbial biomass carbon content, pH and average density have a strong direct negative effect on easily oxidized organic carbon, and particulate organic carbon. Conclusions The interaction between plant community characteristics and soil factors is an important driving factor for soil organic carbon accumulation in inland salt marshes.

Salt marshes are among the most important coastal wetlands and provide critical ecological services, including climate regulation, biodiversity maintenance, and blue carbon sequestration. However, most salt marshes worldwide are shrinking, owing to the effects of natural and human factors, such as climate change and artificial reclamation. Therefore, it is essential to understand the decline in the morphological processes of salt marshes, and accordingly, the likely evolution of these marshes, in order to enable measures to be taken to mitigate this decline. To this end, this study presented an extensive systematic review of the current state of morphological models and their application to salt marshes. The emergence of process-based (PB) and data-driven (DD) models has contributed to the development of morphological models. In morphodynamic simulations in PB models, multiple physical and biological factors (e.g., the hydrodynamics of water bodies, sediment erosion, sediment deposition, and vegetation type) have been considered. The systematic review revealed that PB models have been extended to a broader interdisciplinary field. Further, most DD models are based on remote sensing database for the prediction of morphological characteristics with latent uncertainty. Compared to DD models, PB models are more transparent but can be complex and require a lot of computational power. Therefore, to make up for the shortcomings of each model, future studies could couple PB with DD models that consider vegetation, microorganisms, and benthic animals together to simulate or predict the biogeomorphology of salt marsh systems. Nevertheless, this review found that there is a lack of unified metrics to evaluate model performance, so it is important to define clear objectives, use multiple metrics, compare multiple models, incorporate uncertainty, and involve experts in the field to provide guidance in the further study.

Salt marshes in the southern North Sea are part of the UNESCO World Heritage Site, Wadden Sea, the largest unbroken system of intertidal sand and mud flats in the world. They provide a very high nature value while significantly contributing to coastal flood and erosion risk management as a nature-based element of flood and erosion risk management systems for densely populated coastal areas. Climate change-induced sea-level rise is a significant concern: an integrated approach to salt marsh management adapted to the effects of climate change necessitates an understanding of the impact of different management strategies. This review commences with a description of the biogeomorphological conditions and processes in salt marshes for a better understanding of the natural dynamics and how they are influenced by management and climate change. Next, the impact of salt marshes on hydrodynamic processes and their role as nature-based elements of flood and erosion risk management is presented; management options and implementation methods are discussed and analysed concerning coastal flood management and nature conservation requirements. In conclusion, targeted salt marsh management needs to consider the initial conditions and the development aims of the specific site are integrated into a conceptual framework. Salt marshes have the potential to adapt to sea-level rise, thereby contributing to the long-term protection of coastal areas.

Background: The study of soil organic carbon characteristics and its relationship with soil environment and vegetation types is of great significance to the evaluation of soil carbon sink provided by inland salt marshes. This paper reports the characteristics of soil organic carbon fractions in 0–50 cm soil layers at four vegetation communities of the Qinwangchuan salt marsh. Results: (1) The soil organic carbon content of Phragmites australis community (9.60 ± 0.32 g/kg) was found to be higher than that of Salicornia europae (7.75 ± 0.18 g/kg) and Tamarix ramosissima (4.96 ± 0.18 g/kg) and Suaeda corniculata community (4.55 ± 0.11 g/kg). (2) The soil dissolved organic carbon, particulate organic carbon and soil microbial biomass carbon in 0–50 cm soil layer of Phragmites australis community were higher, which were 0.46 ± 0.01 g/kg, 2.81 ± 0.06 g/kg and 0.31 ± 0.01 g/kg, respectively. (3) Soil organic carbon was positively correlated with dissolved organic carbon, particulate organic carbon, and microbial biomass carbon, and negatively correlated with easily oxidized organic carbon. (4) Above-ground biomass has a strong direct positive effect on soil organic carbon, total nitrogen and pH have a strong direct positive effect on microbial biomass carbon content, pH and average density have a strong direct negative effect on easily oxidized organic carbon, and particulate organic carbon. Conclusions: The interaction between plant community characteristics and soil factors is an important driving factor for soil organic carbon accumulation in inland salt marshes. [ABSTRACT FROM AUTHOR]

Management and monitoring of vulnerable coastal marshes rely on accurate ground height estimates. However, marsh surface characteristics such as vegetation and water presence complicate aerial remote sensing of the ground. Towards developing an improved understanding and techniques for these remote sensing efforts, this study established relationships among data collection flight altitude, surface characteristics, and ground height estimate accuracy within Juncus roemerianus Scheele-dominated marshes. Uncrewed Aerial System (UAS) Light Detection and Ranging (LiDAR) sampling was conducted at five altitudes for five marsh sites and one local control site. Survey-grade topographic measurements and marsh surface characteristics were recorded at each site for comparison. Root Mean Square Error (RMSE) and linear mixed-effects modeling were used to quantify relationships among vertical error, altitude, and surface characteristics. For low (24–72 m) and high (96–120 m) altitudes Above Ground Level (AGL), the RMSE values were 49 cm and 17 cm, respectively. Despite this appreciable improvement in accuracy with increasing flight altitude, point density values of these datasets limit applications. Linear mixed-effects modeling further emphasized the complex relationships between sensor footprint size, surface characteristics, and ground height estimates. These findings have direct implications for elevation modeling and monitoring efforts of frequently inundated, coastal marshes. [ABSTRACT FROM AUTHOR]

Questions: What role do soil seed banks play in the resilience of coastal freshwater wetland vegetation communities? How might soil seed bank composition and similarity to standing vegetation drive changes in vegetation expression, particularly given projected changes in climate? Location: Sixty wooded coastal freshwater wetlands in southeast Queensland, Australia. Methods: We surveyed standing vegetation and investigated soil seed bank composition through an 8‐month‐long emergence experiment. Results: Soil seed bank assemblages were dominated by forb and sedge species (23% exotic), but composition varied throughout the study region. Spatial (north–south) and land‐use (urban–rural) gradients explained some variation in soil seed bank composition. Soil moisture and groundwater dependence also influenced species distributions, particularly for freshwater wetland species. The similarity of soil seed banks to standing vegetation was low. Species present in both extant and soil seed bank assemblages were commonly native wetland taxa, including one salt marsh species (Juncus kraussii). Conclusions: Projected climatic changes will likely drive changes in coastal freshwater wetland vegetation communities through increases in the frequency and intensity of disturbances (e.g., storm surge). Our results suggest that regeneration from soil seed banks could promote four potential scenarios: (1) expansion of weed communities, (2) expansion of salt marsh communities, (3) maintenance and expansion of wetland/terrestrial species, and (4) transformation to an unvegetated open water zone because of reduced regeneration success under changing conditions. These diverse vegetation futures highlight the vulnerability of wooded coastal freshwater wetlands and the need for research and management interventions to maintain their biodiversity and ecosystem services. [ABSTRACT FROM AUTHOR]

In the United States (US), salt marshes are especially vulnerable to the effects of projected sea level rise, increased storm frequency, and climatic changes. Sentinel-2 data offer the opportunity to observe the land surface at high spatial resolutions (10 m). The Sentinel-2 data, encompassing Cumberland Island National Seashore, Fort Pulaski National Monument, and Canaveral National Seashore, were analyzed to identify temporal changes in salt marsh presence from 2016 to 2020. ENVI-derived unsupervised and supervised classification algorithms were applied to determine the most appropriate procedure to measure distant areas of salt marsh increases and decreases. The Normalized Difference Vegetation Index (NDVI) was applied to describe the varied vegetation biomass spatially. The results from this approach indicate that the ENVI-derived maximum likelihood classification provides a statistical distribution and calculation of the probability (>90%) that the given pixels represented both water and salt marsh environments. The salt marshes captured by the maximum likelihood classification indicated an overall decrease in salt marsh area presence. The NDVI results displayed how the varied vegetation biomass was analogous to the occurrence of salt marsh changes. Areas representing the lowest NDVI values (−0.1 to 0.1) corresponded to bare soil areas where a salt marsh decrease was detected. [ABSTRACT FROM AUTHOR]

Invasive species usually benefit more than native species from increases in nutrient availability. Phenotypic plasticity in above‐ground traits has often been used to explain the superiority of invasive species in response to increased nutrient availability. However, it remains largely unclear whether and how root trait plasticity predicts the ascendancy of invasive plants following nutrient enrichment.Using a 3‐year field nitrogen (N) enrichment experiment, we evaluated the effect of N enrichment on the root traits and growth performance of a globally invasive cordgrass, Spartina alterniflora, and a co‐occurring native plant, Phragmites australis.We found that S. alterniflora exhibited high plasticity in root traits in response to N enrichment, whereas the root traits of P. australis largely remained unresponsive to fertilization. Specifically, in response to N enrichment, S. alterniflora decreased soil exploitation with a lower length ratio of lateral to adventitious roots. However, the root traits of S. alterniflora shifted to be more acquisitive under N enrichment with higher root N concentrations and lower root tissue density. Moreover, there were a series of anatomical adjustments in the adventitious roots of S. alterniflora in response to N enrichment, such as a thicker diameter, lower living cortex‐to‐stele ratio and higher xylem‐to‐root area ratio. These plastic adjustments in root traits jointly resulted in fast nutrient uptake and transportation in S. alterniflora, boosting its above‐ground productivity under fertile N conditions.Our study demonstrated that greater plasticity in root traits enables a globally successful invasive species to take advantages of increased nutrient availability, potentially increasing its invasiveness. We suggest that consideration of root traits can improve our understanding of below‐ground mechanisms underlying invasion under global nutrient enrichment. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Salt marshes can attenuate nutrient pollution and store large amounts of 'blue carbon' in their soils, however, the value of sequestered carbon may be partially offset by nitrous oxide (N2O) emissions. Global climate and land use changes result in higher temperatures and inputs of reactive nitrogen (Nr) into coastal zones. Here, we investigated the combined effects of elevated temperature (ambient + 5℃) and Nr (double ambient concentrations) on nitrogen processing in marsh soils from two climatic regions (Quebec, Canada and Louisiana, U.S.) with two vegetation types, Sporobolus alterniflorus (= Spartina alterniflora) and Sporobolus pumilus (= Spartina patens), using 24-h laboratory incubation experiments. Potential N2O fluxes increased from minor sinks to major sources following elevated treatments across all four marsh sites. One day of potential N2O emissions under elevated treatments (representing either long-term sea surface warming or short-term ocean heatwaves effects on coastal marsh soil temperatures alongside pulses of N loading) offset 15–60% of the potential annual ambient N2O sink, depending on marsh site and vegetation type. Rates of potential denitrification were generally higher in high latitude than in low latitude marsh soils under ambient treatments, with low ratios of N2O:N2 indicating complete denitrification in high latitude marsh soils. Under elevated temperature and Nr treatments, potential denitrification was lower in high latitude soil but higher in low latitude soil as compared to ambient conditions, with incomplete denitrification observed except in Louisiana S. pumilus. Overall, our findings suggest that a combined increase in temperature and Nr has the potential to reduce salt marsh greenhouse gas (GHG) sinks under future global change scenarios. [ABSTRACT FROM AUTHOR]