Salt Marsh Ecosystems Research Articles

Global change in marine coastal habitats impacts insect populations and communities.

Salt marsh and mangrove coastal ecosystems provide critical ecosystem services, but are being lost at an alarming rate. Insect communities in these ecosystems are threatened by human impacts, including sea level rise, habitat loss, external inputs including nutrients, metals, and hydrocarbons, as well as weather events, such as hurricanes. While some disturbances are felt throughout the food web (e.g. hurricanes), others are mediated by impacts on the dominant plants (e.g. nutrient subsidies). The impacts of these disturbances on insects/spiders and their rate of recovery is dependent on trophic level, life history, and diet breadth. While we understand impacts of single disturbances relatively well, we have very little understanding of how multiple disturbances interact to affect insect communities.

Fairy circles reveal the resilience of self-organized salt marshes.

Spatial patterning is a fascinating theme in both theoretical and experimental ecology. It reveals resilience and stability to withstand external disturbances and environmental stresses. However, existing studies mainly focus on well-developed persistent patterns rather than transient patterns in self-organizing ecosystems. Here, combining models and experimental evidence, we show that transient fairy circle patterns in intertidal salt marshes can both infer the underlying ecological mechanisms and provide a measure of resilience. The models based on sulfide accumulation and nutrient depletion mechanisms reproduced the field-observed fairy circles, providing a generalized perspective on the emergence of transient patterns in salt marsh ecosystems. Field experiments showed that nitrogen fertilization mitigates depletion stress and shifts plant growth from negative to positive in the center of patches. Hence, nutrient depletion plays an overriding role, as only this process can explain the concentric rings. Our findings imply that the emergence of transient patterns can identify the ecological processes underlying pattern formation and the factors determining the ecological resilience of salt marsh ecosystems.

Transcriptome analysis of immune-related genes in Sesarmops sinensis hepatopancreas in reaction to peptidoglycan challenge

Sesarmops sinensis is a dominant omnivorous crab species, which plays an important ecological function in salt marsh ecosystems. To better understand its immune system and immune related genes under pathogen infection, the transcriptome was analyzed by comparing the data of S. sinensis hepatopancreas stimulated by PBS and PGN. A set of assembly and annotation identified 39,039 unigenes with an average length of 1105 bp, obtaining 1300 differentially expressed genes (DEGs) in all, which included 466 remarkably up-regulated unigenes and 834 remarkably down-regulated unigenes. In addition, based on mensurable real time-polymerase chain reaction and high-throughput sequencing, several immune responsive genes were found to be markedly up-regulated under PGN stimulation. In conclusion, in addition to enriching the existing transcriptome data of S. sinensis, this study also clarified the immune response of S. sinensis to PGN stimulation, which will help us to further understand the crustacean's immune system.

Atmospheric concentrations and ecosystem fluxes of CH2Cl2, CHCl3 and CCl4 along tidal and vegetation gradients within a coastal salt marsh in Eastern China

There is a causal relationship between atmospheric concentrations and ecosystem fluxes of DCM, CF, and CT. Atmospheric concentrations of these gases likely regulate ecosystem fluxes, and they may also be influenced in turn by exchanges with the ecosystem. The relationship between atmospheric concentrations and fluxes of DCM, CF, and CT is bound to affect the occurrence and fate of these gases in the environment. However, how atmospheric concentrations and ecosystem fluxes are related remains poorly understood. Here, the dynamics of atmospheric concentrations and ecosystem fluxes of these three gases were investigated using samples from three transects along tidal and vegetation gradients within a coastal salt marsh in Eastern China. Substantial variation was found among the dynamics of the three gases, which also showed different relationships between their atmospheric concentrations and ecosystem fluxes. In general, the ecosystem flux of each gas was negatively correlated with its ambient concentration in the atmosphere, although this varied across time and space. For example, high ambient concentrations of DCM and CT often corresponded with high ecosystem fluxes, but high ambient concentrations of CF corresponded to low ecosystem fluxes. Gas fluxes were significantly correlated, suggesting that the three gases have a common source. However, there may be differences between marine and terrestrial inputs, helping to explain the inconsistent flux-atmospheric concentration relationships. External inputs (e.g., coastal seawater and terrestrial biomass burning) may act to regulate ambient gas concentrations in the coastal salt marsh atmosphere, altering patterns of exchange between the ecosystem and atmosphere. Salt marsh ecosystems may be worthy of attention as sinks for DCM, CF, and CT. Ecological restoration of coastal salt marshes is therefore critical to help mitigate high atmospheric concentrations of DCM, CF, and CT.

Abundance and niche specificity of different types of complete ammonia oxidizers (comammox) in salt marshes covered by different plants

The recently discovered complete ammonia oxidizers (comammox), which are ubiquitous in various natural and artificial ecosystems, have led to a paradigm shift in our understanding of aerobic nitrification. The coastal salt marsh covered by various plant species is an important ecosystem to link nitrogen cycles of terrestrial and marine environments; however, the distribution and structure of comammox in such ecosystems have not been clearly investigated. Here, we applied quantitative PCR and partial nested-PCR to investigate the abundance and community composition of comammox in salt marsh sediment samples covered by three plant types along the southern coastline of China. Our results showed a predominance of comammox clade A in majority of the samples, suggesting their ubiquity and the important role they play in nitrification in salt marsh ecosystems. However, variations by the sites were found when comparing the abundance of subclades of comammox clade A. Redundancy analysis demonstrated a coexistence pattern by comammox clade A.1 with ammonia-oxidizing archaea and comammox clade A.2 with canonical ammonia-oxidizing bacteria, indicating their differences in potential niche preference. However, the abundance of comammox clade B was lower than that of comammox clade A and other ammonia oxidizers in most samples. Moreover, pH and salinity were found to be the most significant factors affecting comammox community structures, suggesting their roles in driving niche partitioning of comammox, whereas plant types did not show a significant effect on the comammox community structure. Our study provided insights into the abundance, community diversity, and niche partitions of comammox, broadening the current understanding of the relationship of comammox with other ammonia oxidizers in salt marsh ecosystems.

Inoculating rhizome-propagated Sporobolus pumilus with a native mycorrhizal fungus increases salt marsh plant growth and survival

Salt marshes are ecosystems of significant ecological importance for coastal stability and fundamental roles in marine ecosystems. Salt marshes are declining due to anthropogenic and natural causes including sea level rise. Coastal restoration efforts have increased worldwide, but many fail in long-term coastal stability. We used a naturally occurring arbuscular mycorrhizal fungus (AMF) to test whether survival and early growth of the salt marsh grass Sporobolus pumilus (formerly Spartina patens) improved under simulated salt marsh conditions. Using a tidal mesocosm bench, we grew inoculated plants with varying AMF treatments under simulated tidal regimes to determine if AMF could aid in establishment of healthy Sporobolus communities. Rhizome-derived S. pumilus had greater survival and grew faster than seed-derived plants. Plants inoculated with propagated AMF consistently outperformed both sterile and native sediment controls in terms of plant survival and growth. Use of rhizome-derived Sporobolus inoculated with propagated Funneliformis geosporum showed the most promise in producing successful plant populations for salt marsh restoration. This may be due to plant life stage and improved plant nutrient status, allowing rhizome-derived plants to grow more quickly than seed-derived plants. Using these plants in future large-scale restoration may increase re-establishment of salt marsh ecosystems.

Population dynamics of Armases rubripes in southwestern Atlantic salt marshes: seasonality, abiotic influence and reproductive biology

The knowledge about reproductive biology and influence of seasonality and abiotic factors over crabs improves the understanding of their role in salt marsh ecosystems. Focusing on Armases rubripes, we analyzed of 2,206 individuals in terms of abundance, sex ratio, morphometry and egg count, monthly sampled along two years. Through Generalized Linear Mixed-effects Models we found a continuous presence of A. rubripes at Patos Lagoon Estuary (PLE), Brazil, with seasonal peaks of males and non-ovigerous females mostly during cold autumn–winter. The opposite pattern was found to ovigerous females, when they were prevalent during warm spring–summer and early autumn. The overall sex ratio indicated a predominance of males over females (1.2♂: 1♀), but male peaks during summer months (mainly ≥2♂: 1♀) could be due the migration of females to spawning grounds. The first maturation size based on the carapace width (CW) was estimated at 7.9 mm for males and 7.0 mm for females. The highest gain in fecundity (79.2%) occurred in the width class immediately after the transitional maturation stage (10.1–11.0 mm CW), suggesting that size influences in the ability of ovigerous females in the transitional maturation stage to reach the maximum reproductive outputs. The fecundity of 2,880 (± 1,964) eggs shown a low fecundity for A. rubripes along the sampled region. Our results bring a new information about the occurrence and reproductive biology of this species in salt marshes from medium latitudes, opening the discussion about our findings.

Long-term invasion dynamics of Spartina increase vegetation diversity and geomorphological resistance of salt marshes against sea level rise

The cordgrass Spartina anglica C.E. Hubbard (Poaceae) is an invasive transformer in many salt marsh ecosystems worldwide. Relatively little is known about the capacity of Spartina to accelerate salt marsh succession and to protect salt marshes against sea level rise. We analyzed long-term changes in vegetation and elevation in mainland salt marshes of the European Wadden Sea in Schleswig-Holstein, Germany, to estimate the impact of non-native Spartina on the geomorphological resistance of salt marshes to sea level rise and on changes in species diversity. From 1989 to 2019, the Spartina-zone shifted and expanded upwards to elevations of the high marsh zone and Spartina increased in frequency in several salt marsh vegetation communities. At sites where Spartina dominated the vegetation already three decades ago, elevation and species diversity increased with a higher rate compared to sites lacking Spartina. The median change rates reached for elevation MHT +8.6 versus +1.5 mm per year, for species richness +3 versus pm0 species per three decades, and for evenness +0.04 versus −0.08 per three decades, regarding plots with versus without former Spartina dominance, respectively. Invasion of salt marshes by Spartina and its continued, long-term presence were associated with increased elevation and species diversity in the face of sea level rise.

Archaeological herbivore δ13C and δ34S provide a marker for saltmarsh use and new insights into the process of 15N-enrichment in coastal plants

Saltmarshes are tremendously important culturally and ecologically because they can provide abundant nutrient-rich fodder for grazing livestock, with relatively little resource investment. They also perform critical ecological services, including detoxifying water and stabilizing coastlines. For these reasons, methods for investigating the nature and extent of past saltmarsh use have significant potential to provide new insights into patterns in coastal adaptations among past agricultural societies as well as paleoenvironmental change. Stable nitrogen isotope (δ15N) analyses of animal bone collagen have been used to investigate ancient saltmarsh use based on the idea that plants growing in saline and/or coastal regions can have higher δ15N values. However, interpretation of δ15N evidence for saltmarsh use can be challenging because variation in terrestrial nitrogen sources and cycling can result in similarly elevated in δ15N values in animals that did not feed in saltmarshes. Ecological studies show that stable carbon (δ13C) and sulfur (δ34S) isotope analyses are well suited for investigating saltmarsh use because key species (particularly those in the genus Spartina) that dominate these ecosystems in many areas of the world are C4 plants capable of incorporating sulfuide-derived, 34S-depleted sulfur. We investigate the utility of δ13C, δ34S, and δ15N for tracking saltmarsh use in archaeological herbivores (n = 80) from seventeenth-to-eighteenth-century Acadian settlements in Canada, which were renowned for their agricultural use of saltmarsh ecosystems. Results show extreme variation in δ13C and δ34S consistent with feeding along C3-to-C4 and sulfate-to-sulfide-derived sulfur continuums. Significant correlations between δ13C and δ34S suggests that variation in these isotopic compositions reflects the relative importance of Spartina in past Acadian animal husbandry. These findings indicate that, even in areas where other 13C-eniched food sources are available (e.g., seaweeds, maize), combined δ13C and δ34S analyses should be able to identify Spartina use in coastal regions. A strong negative correlation was also found between δ34S and δ15N, suggesting that processes driving coastal sulfur and nitrogen cycles in the region are coupled (independently of Spartina consumption) and provide new insights into the mechanism behind 15N enrichment observed in saltmarsh plants.

Stress gradients interact with disturbance to reveal alternative states in salt marsh: Multivariate resilience at the landscape scale

Abstract Stress gradients influence many ecosystem processes and properties, including ecosystem recovery from and resistance to disturbance. While recent analytical approaches have advanced multivariate metrics of ecosystem resilience that allow quantification of conceptual resilience models and identification of thresholds of state change, these approaches are not often translated to landscape scales. Using natural and restored salt marshes in Louisiana, USA, we quantified plant community recovery and resistance metrics along flooding stress gradients. n‐dimensional hypervolumes of plant community biomass and structure were simulated using field data collected from disturbance‐recovery experiments. The relationships between multivariate resilience metrics and flooding stress gradients were then mapped at community‐ and landscape‐relevant scales by scaling with airborne‐derived data across the region. Greater pre‐disturbance abiotic stress decreased live below‐ground, but not above‐ground, biomass, and ultimately led to lower post‐disturbance total recovery, recovery rates and resistance of plant communities. Vegetated plots flooded >52% of the time transitioned to an alternative, unvegetated state after disturbance. Mapping revealed differences in spatial patterns of resilience—highlighting low, interior marsh edges as especially vulnerable to the combination of chronic flooding stress and acute disturbance. At the landscape scale, approximately half of the area (48%) is vulnerable to state change after pulse disturbances. Synthesis. Ultimately, we quantify the ball‐and‐cup conceptual model for a salt marsh ecosystem and its alternative state, mudflat. We find that increasing abiotic stress due to climate change diminishes ecosystem resilience, but the interaction with common episodic disturbances is necessary to reveal transitions to alternative states and quantify state change thresholds. Quantifying and mapping resilience and where alternative states may exist in this fashion improves ecologists' ability to investigate the mechanisms of stress gradient control on emergent ecosystem properties while providing spatially explicit resources for managing ecosystems according to their projected resilience.

Spartina alterniflora invasions reduce soil fungal diversity and simplify co-occurrence networks in a salt marsh ecosystem

Soil fungal communities drive diverse ecological processes and are critical in maintaining ecosystems' stability, but the effects of plant invasion on soil fungal diversity, community composition, and functional groups are not well understood. Here, we investigated soil fungal communities in a salt marsh ecosystem with both native (Suaeda salsa) and exotic (Spartina alterniflora) species in the Yellow River Delta. We characterized fungal diversity based on the PCR-amplified Internal Transcribed Spacer 2 (ITS2) DNA sequences from soil extracted total DNA. The plant invasion evidently decreased fungal richness and phylogenetic diversity and significantly altered the taxonomic community composition (indicated by the permutation test, P < 0.001). Co-occurrence networks between fungal species showed fewer network links but were more assembled because of the high modularity after the invasion. As indicated by the fungal Bray-Curtis and weighted UniFrac distances, the fungal community became homogenized with the invasion. FUNGuild database analyses revealed that the invaded sites had a higher proportion of saprophytic fungi, suggesting higher organic matter decomposition potential with the invasion. The plant invasion dramatically inhibited the growth of pathogenic fungi, which may facilitate the expansion of invasive plants in the intertidal habitats. Soil pH and salinity were identified as the most important edaphic factors in shaping the fungal community structures in the context of Spartina alterniflora invasion. Overall, this study elucidates the linkage between plant invasion and soil fungal communities and poses potential consequences for fungal contribution to ecosystem function, including the decomposition of soil organic substrates.

Theory of scale-dependent feedback: An experimental validation and its significance for coastal saltmarsh restoration

Theory of self-organization, i.e., scale-dependent feedback (SDF), has been widely used to explain mechanisms of spatial patterns in different ecosystems. Studies have demonstrated that self-organization is one of the mechanisms through which ecosystem resilience is maintained. However, the application of SDF in real ecological restoration practices is a challenge due to the lack of a controlled experimental validation. In the present study, multiple scales of vegetation patches were constructed along an elevation gradient in the saltmarsh ecosystem on Nanhui coasts and were investigated to verify if there was an effect of SDF. Results of the density-variation curves analyses revealed that most constructed self-organized patches could survive and an optimal curve was found of which the density-dependent feedback was proven through fitting with the asymptotic regression model. The large vegetation patches exhibited considerable increases in density when compared to the small vegetation patches, which occurred in challenging environments, i.e., on the verges of elevation thresholds, and with a tendency to shrink. Analyses using one-way ANOVA revealed that there was an optimal patch scale and elevation in the study area, i.e., 1 m × 1 m scale and 3.2 m, respectively. Optimal scale and elevation provide a comprehensively explanations of SDF, although with the positive effects gradually decreased along the distance away from the optimal condition. The present study provides novel insights on applying the theory of SDF in facilitating the restoration process of coastal saltmarshes.

Seascape Configuration Influences the Community Structure of Marsh Nekton

Around the globe, salt marsh ecosystems are rapidly changing, leading to alterations in both the amount, and configuration of marsh habitats. Sea level rise is a key driver of salt marsh change and is decreasing marsh habitat cover while increasing fragmentation. Such changes in seascape structure are expected to alter the ecological communities associated with marsh habitats. The influence of seascape structure on marsh nekton community structure is not well characterized, especially in coastal areas of the Gulf of Mexico, such as Louisiana (USA). Louisiana is losing marsh habitat at an unprecedented rate, and the resulting habitat loss and fragmentation provides a unique study system to investigate how marsh seascape structure impacts the nekton community. In this study, seascape structure was characterized at the 1- and 5-km scale at sampling points across several coastal basins to test marsh seascape structure effects on nekton community characteristics. Nekton communities were sampled using seine nets across coastal Louisiana in 2007. Total nekton community structure was found to be spatially driven. Both nekton species richness and nekton abundance were influenced by the shape of marsh patches and proportion of landscape marsh measured at either scale. While species richness differed only between some of the basins, each basin was found to have a statistically distinct community structure. Marsh shape influenced brown and white shrimp size. However, the response direction was found to be species specific, with brown shrimp size increasing in marshes with more complex shape while white shrimp size decreased. This study demonstrates that both environmental drivers and seascape structure play important roles in structuring marsh nekton communities, and that these responses can be species-specific. In order to project complex interactions between coastal land loss and their communities, a holistic framework of community structure, environmental drivers, and seascape characteristics is recommended.

Sulfur isotopes (δ34S) in Arctic marine mammals: indicators of benthic vs. pelagic foraging

Consumer tissue stable carbon isotope compositions (δ13C) are well established indicators of benthic and pelagic foraging in marine ecosystems. Stable sulfur isotope compositions (δ34S) are also potentially useful in this regard but have not been widely utilized outside of estuaries and salt marsh ecosystems. To test the ability of δ13C and δ34S to reflect benthic and pelagic foraging, we analyzed the stable carbon, nitrogen (δ15N), and sulfur isotope compositions of bone collagen from walrus (an obligate benthic feeder) and ringed seal (a mixed benthic/pelagic feeder) sampled from across the North American Arctic. Both had relatively low δ34S values compared to those typically observed in marine consumers. These data suggest an important role for benthic microalgae in coastal marine food webs in the Arctic. At all of the 10 locations where both taxa could be sampled, walrus had lower δ34S values than ringed seal, suggesting that this measurement is a useful indicator of benthic and pelagic foraging in nearshore Arctic environments. Contrary to expectations, there were no consistent differences in δ13C between walrus and ringed seal at any of these sites, suggesting that this measurement may not always be best interpreted in light of benthic vs. pelagic foraging, particularly when comparisons are made across trophic levels. When the foraging ecology of a consumer is unknown, our data suggest that δ34S may be a more sensitive indicator of the relative importance of benthic and pelagic prey in the diet than δ13C.

Carbon Balance in Salt Marsh and Mangrove Ecosystems: A Global Synthesis

Mangroves and salt marshes are among the most productive ecosystems in the global coastal ocean. Mangroves store more carbon (739 Mg CORG ha−1) than salt marshes (334 Mg CORG ha−1), but the latter sequester proportionally more (24%) net primary production (NPP) than mangroves (12%). Mangroves exhibit greater rates of gross primary production (GPP), aboveground net primary production (AGNPP) and plant respiration (RC), with higher PGPP/RC ratios, but salt marshes exhibit greater rates of below-ground NPP (BGNPP). Mangroves have greater rates of subsurface DIC production and, unlike salt marshes, exhibit active microbial decomposition to a soil depth of 1 m. Salt marshes release more CH4 from soil and creek waters and export more dissolved CH4, but mangroves release more CO2 from tidal waters and export greater amounts of particulate organic carbon (POC), dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC), to adjacent waters. Both ecosystems contribute only a small proportion of GPP, RE (ecosystem respiration) and NEP (net ecosystem production) to the global coastal ocean due to their small global area, but contribute 72% of air–sea CO2 exchange of the world’s wetlands and estuaries and contribute 34% of DIC export and 17% of DOC + POC export to the world’s coastal ocean. Thus, both wetland ecosystems contribute disproportionately to carbon flow of the global coastal ocean.

Halophyte bio-optical phenotyping: A multivariate photochemical pressure index (Multi-PPI) to classify salt marsh anthropogenic pressures levels

Salt marsh ecosystems are extremely impacted by human activities whilst also acting as sinks of contaminants such as heavy metals. Halophytic plant species can survive and thrive in estuarine and coastal areas with higher salt conditions that are generally not favourable to most plants. Halophyte distribution and abundance clearly relate to anthropogenic pressure levels and thus the impact of heavy metals needs to be rapidly assessed and monitored in a fast-developing world. To assess and manage this impact the search for suitable and efficient biomarkers is of great importance, aiming to produce a clear picture of environmental quality. The present work aimed to evaluate the application of optical tools, like non-invasive chlorophyll a pulse amplitude modulated (PAM) fluorometry, in four halophytic species (Halimione portulacoides, Sarcocornia fruticosa, Spartina maritima and Spartina patens), from three salt marshes of the Tagus estuary with different degrees of contamination, to investigate biomarkers for inclusion in a Multivariate Photochemical Pressure Index (Multi-PPI) destined for ecological quality assessment. The application of this index allowed to distinguish between less (Alcochete) and more (Rosário and Seixal) heavy metal contaminated salt marshes. This was observed particularly for S. maritima, in which Multi-PPI was lower for the higher contaminated sites, albeit this pattern was similarly observed in S. patens and S. fruticosa. On the other hand, the Multi-PPI index for H. portulacoides, a phytoextractor species, increased with the contamination gradient along the three salt marshes, and therefore this strategy should be considered when applying this index. Therefore, since these species are well represented in the Mediterranean, the use of optical tools to generate an easy fast index will have a great impact on the future of transitional ecosystem pollution impact assessments as well as in ecotoxicology research.

Soil carbon storage and carbon sources under different Spartina alterniflora invasion periods in a salt marsh ecosystem

As an important component of global change, plant invasion threaten the sustainability of global ecosystems and may alter the carbon dynamics in the invaded area. Knowledge of the effects of Spartina alterniflora invasion on soil organic carbon (SOC) and soil inorganic carbon (SIC) stocks and their profile distribution is limited in coastal salt marshes, which are referred as important “blue carbon” ecosystems. A short-term invasion chronosequence of 2–10 years was used to evaluate the responses of SOC and SIC over the invasion period in the Yellow River Estuary, China. The 13C isotope content was analyzed in soil, plant tissue, and sediment debris to infer the contribution of invasion to SOC accumulation in the invaded salt marshes. The results showed that more than 80% of the soil C was inorganic, and this percentage was higher in native sites and in the newly invaded areas. SOC accumulated linearly with the invasive time in the top 100 cm soil. The SOC accumulation rate varied along the soil profile, and was 0.10, 0.13, and 0.40 kg C m−2 yr−1 in the top 20cm, 40cm, 100cm soils, respectively. The 13C isotope analysis demonstrated that debris-derived C was dominant in the native salt marshes (62.2% on average), while plant-derived C increased with the invasive time. Structural equation modeling (SEM) showed that the SIC loss in the top 40 cm with invasion could be indirectly attributed to the soil acidification in the alkaline soil and directly related to soil Ca loss. Our results also suggested that SIC loss would partially offset the CO2 sequestration associated with SOC burial caused by the invasion. This work indicates causal relationships between plant invasions and soil carbon pools and highlights the nonnegligible importance of inorganic C in coastal blue carbon budgets.

Adaptation of restoration target with climate change: the case of a coastal peatland

As a rise in sea level is expected with climate change, peat-extracted peatlands located in coastal zones are more vulnerable to saltwater intrusion. Seawater contamination may prevent revegetation of typical bog species (e.g., Sphagnum, ericaceous shrubs) generally intolerant to saline conditions. Spontaneous revegetation was studied in a 27-year post-extracted bog that has been contaminated with seawater in New Brunswick (Eastern Canada). This study aimed (i) to evaluate spontaneous plant regeneration on saline but still acidic, organic soil; and (ii) to relate the recolonized vegetation patterns to the main environmental conditions. Of the seven plant communities found in the sea-contaminated bog, none were typical of bogs, and Sphagnum mosses were poorly represented. Plants communities and chemical properties were rather representative of salt marsh ecosystems (i.e., Carex paleacea, Sporobolus michauxianus, Empetrum nigrum, Myrica gale; neutral pH and nutrient-rich, namely P, Mg, and NH4+). Areas with low levels of spontaneous revegetation were associated with harsh chemical conditions (i.e., acid pH, high electrical conductivity, and nutrient-poor). Considering the aggravating factors that will persist with climate change, restoration of coastal bogs contaminated with seawater should aim to re-establish salt marsh ecosystems, given that spontaneous revegetation patterns and chemical conditions clearly do not allow the establishment of bog plant communities.

Corrigendum

Global Change BiologyVolume 26, Issue 9 p. 5342-5342 CORRIGENDUMFree Access Corrigendum This article corrects the following: A synthesis of methane emissions from shallow vegetated coastal ecosystems Alia N. Al-Haj, Robinson W. Fulweiler, Volume 26Issue 5Global Change Biology pages: 2988-3005 First Published online: March 16, 2020 First published: 22 July 2020 https://doi.org/10.1111/gcb.15192Citations: 1AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL In the paper by Al-Haj and Fulweiler (2020), global warming potential (GWP) and sustained flux global warming potential (SGWP) were calculated incorrectly. GWP should be calculated using gas emissions in gas mass units (Neubauer & Megonigal, 2015). We thank Judith Rosentreter for bringing the calculation error to our attention and Damien Maher and Patrick Megonigal for consultation on the correction. The updated version of Table 1 includes global flux rate, GWP or SGWP calculated via the following equations for the mean CH4 flux rate of each ecosystem: where r is the mean CH4 flux rate in µmol m−2 day−1 for each ecosystem and A is the area of the ecosystem in km2. where GFR is the mean global CH4 flux rate for each ecosystem and we use the 100 year global warming potential multiplier (32 or 45, respectively) from Neubauer and Megonigal (2015). TABLE 1. Global CH4 emission estimates from vegetated coastal ecosystems (VCEs) and their impact on global carbon cycling. Median CH4 fluxes, global CH4 flux estimates (Supporting Text 3 in Data S1), increase in global marine methane budget (Supporting Text 4 in Data S1), global warming potential (above) and sustained flux global warming potential (above) from VCEs. Values with the same lower case letter are not significantly different Mangrove Salt marsh Seagrass CH4 flux rate (µmol CH4 m−2 day−1) Mean ± SE 4,556.96 ± 1,102.06 3,534.90 ± 1,331.21 108.24 ± 19.72 Median 279.17a 224.44a 64.80b Range −67.33 to 72,867.83 −92.60 to 94,129.68 1.25–401.50 Aerial extent (km2) 137,760–152,361 55,000 788,000–1,646,788 Global CH4 flux rate (Tmol CH4 year−1) Mean ± SE 0.23 ± 0.06 0.25 ± 0.06 0.071 ± 0.027 0.031 ± 0.006 0.065 ± 0.012 Increase in global marine CH4 budget (%) 40.2–44.5 12.5 5.4–11.4 Global C burial (Tg C year−1)* Mean ± SE 31.1 ± 5.4 34.4 ± 5.9 11.99 ± 1.32 108.74 ± 29.90 227.26 ± 62.57 Global warming potential (Tg CO2eq year−1) Mean 117.61–130.08 36.42 15.98–33.39 Sustained flux global warming potential (Tg CO2eq year−1) Mean 165.39–182.92 51.22 22.47–46.96 Global area source McLeod et al. (2011) Mcowen et al. (2017) Jayathilake and Costello (2018), Davidson and Finlayson (2019) * Global C burial rates from McLeod et al. (2011). Subsequently, section 6: Global warming potential is also incorrect. Using the correct calculations for GWP and SGWP, mangroves and salt marshes release ~1–1.5 g of CO2 equivalent CH4 for every gram of CO2-eq C stored when considering the mean CH4 flux rate and seagrasses remain CO2 sinks releasing 1 g of CO2 equivalent CH4 for every 17 g of CO2-eq C stored (Table 1). These results indicate that mangroves and salt marsh ecosystems may be net C storers in some systems and may have net C loss in others. Code detailing step-by-step calculations can be found at https://github.com/aliaalhaj/Al-HajFulweiler2020_MethanefromVCEs_Code. REFERENCE Al-Haj, A. N., & Fulweiler, R. W. (2020). A synthesis of methane emissions from shallow vegetated coastal ecosystems. Global Change Biology, 26, 2988– 3005. https://doi.org/10.1111/gcb.15046 Citing Literature Volume26, Issue9September 2020Pages 5342-5342 ReferencesRelatedInformation

Rapid recovery of carbon cycle processes after the cessation of chronic nutrient enrichment

Salt marshes provide critical ecosystem services including some of the highest rates of carbon storage on Earth. However, many salt marshes receive very high nutrient loads and there is a growing body of evidence indicating that this nutrient enrichment alters carbon cycle processes. While many restoration plans prioritize nutrient management in their efforts to conserve salt marsh ecosystems, there has been little empirical investigation of the capacity for carbon cycle processes to recover once nutrient loading is reduced. To address this, we compared rates of greenhouse gas fluxes (i.e., CO2 and methane) measured using static chambers, and soil organic matter decomposition, using both litter bags and the Tea Bag Index (TBI), during the last two years of a long-term, ecosystem-scale nutrient enrichment experiment (2015–2016) as well as in the first two years of recovery post-enrichment (2017–2018). We found that both ecosystem respiration (Reco) and decomposition processes (i.e., rhizome decomposition and soil organic matter stabilization) were enhanced by nutrient enrichment, but returned to reference ecosystem levels within the first year following the cessation of nutrient enrichment and remained at reference levels in the second year. These results suggest that management practices intended to reduce nutrient loads in coastal systems may, in fact, allow for rapid recovery of carbon cycle processes, potentially restoring the high carbon sequestration rates of these blue carbon ecosystems.