Salt Marsh Values in a Changing World: Examining Sea Level Rise on Tidal Marshes with a Surface Elevation Table

Rising seas are threatening coastal communities and putting added pressures on the natural environment. Sea level rise rates are increasing on a global scale (from 1.7 to 3.2 mm/yr). Salt marshes are not only intertidal habitats acutely influenced by sea levels, but they also provide key ecosystem services such as: buffers against storm surges, habitat for wildlife, carbon dioxide storage, and pollutant filtration. In New England, salt marshes have built at a rate of 1 to 2 mm annually over the past 4,000 years, which has kept pace with sea level rise. However, we do not know if salt marshes can keep building if sea levels rise at a more rapid rate of 4 mm/yr or greater. To monitor how salt marshes are responding to faster sea level rise, we measured salt marsh accretion and elevation change along the coast of New Hampshire at three different marshes (a total of 11 stations) using marker horizons and a Surface Elevation Table (SET). The SET sites were established in two marshes over a decade ago and more recently at a third marsh in 2011. Data were collected in 2013 and the new rates are compared to previous elevation changes. The major findings included an unprecedented marsh elevation growth rate of 4.3 mm/yr, which shows that our marshes are building at rates fast enough to keep up with the current sea level rise. Furthermore, the rate of salt marsh building appears to be greater than the global sea level rate of 3.2 mm/yr, suggesting our local rate of sea level rise may be greater than 3.2mm/year. Salt marshes could provide a valuable indirect measure of local sea level rise

Biodiversity in salt marshes: from the patrimonial value to the ecosystem functioning. The case study of the Mont Saint-Michel bay.

Until 1979, European salt marshes were known only through the inventories of fauna and especially of flora. On such criteria, the salt marshes of the Mont-Saint-Michel bay (France) were regarded as most significant of the French coasts. However, it took 20 years of research on the role of these wetlands of the estuaries-salt marsh systems to highlight the ecological, social and economic interest of this ecotone, between continental and marine systems, a long time considered as territory “without value”, except for stock breeders or hunters

Human activities accelerated the degradation of saline seepweed red beaches by amplifying top‐down and bottom‐up forces

Salt marshes dominated by saline seepweed (Suaeda heteroptera) provide important ecosystem services such as sequestering carbon (blue carbon), maintaining healthy fisheries, and protecting shorelines. These salt marshes also constitute stunning red beach landscapes, and the resulting tourism significantly contributes to the local economy. However, land use change and degradation have led to a substantial loss of the red beach area. It remains unclear how human activities influence the top‐down and bottom‐up forces that regulate the distribution and succession of these salt marshes and lead to the degradation of the red beaches. We examined how bottom‐up forces influenced the germination, emergence, and colonization of saline seepweed with field measurements and a laboratory experiment. We also examined whether top‐down forces affected the red beach distribution by conducting a field survey for crab burrows and density, laboratory feeding trials, and waterbird investigations. The higher sediment accretion rate induced by human activities limited the establishment of new red beaches. The construction of tourism facilities and the frequent presence of tourists reduced the density of waterbirds, which in turn increased the density of crabs, intensifying the top‐down forces such as predators and herbivores that drive the degradation of the coastal red beaches. Our results show that sediment accretion and plant–herbivory changes induced by human activities were likely the two primary ecological processes leading to the degradation of the red beaches. Human activities significantly shaped the abundance and distribution of the red beaches by altering both top‐down and bottom‐up ecological processes. Our findings can help us better understand the dynamics of salt marshes and have implications for the management and restoration of coastal wetlands

Role of fish communities in particulate organic matter fluxes between salt marshes and coastal marine waters in the Mont Saint-Michel bay.

Among the 90 fishspecies censused in the Mont Saint-Michel Bay (France), 23 colonise and forage in the salt marshes during flood. Therefore, this environmentmay play an important trophic and nursery role for these species. This community is largely dominated by mullets (81% of the biomass), Liza ramada and secondarily L. aurata. But gobies (mainly Pomatoschistus minutus and P. lozanoï) and sea bass (Dicentrarchus labrax) are also present; they represent respectively 11% and 4% of the biomass. During the tide cycles, mullets export from salt marshes about 7% of their body weight (FW) containing a mixture of sediment (43%), organic matter (24%) and water (33%). Gobies and sea bass mainly feed on dwelling macro-invertebrates, and they export respectively 4.5% and 10% of their body weight during a tide cycle. Thus, we estimated that 50 tonnes year−1 of particulate organic matter (dry weight POM) are exported from the 4000 ha of salt marshes to the marine coastal waters. These fish communities appear to be POM transporters and could play a significant role in the global energy budgets of coastal environments such as Mont Saint-Michel Bay. According to the seasons and the years, the energy exported by fish communities is assumed to range between 0 and 10% of the total POM output

Rethink Connecticut’s Tidal Salt Marsh Restoration Efforts

Due to man-made and natural events over recent years, the salt marshes that protect Connecticut’s coastline have been severely damaged. Salt marshes protect Connecticut’s shoreline from storms and provide an irreplaceable ecosystem for the state’s entire length between New York and Rhode Island. The Connecticut state government in collaboration with shoreline organizations have developed plans to create processes to begin restoring the coastal salt marshes. Some of these proposals are considered unsightly by shoreline residents and their communities. Without their support, restoring salt marshes will be a far more difficult process. Through the use of design thinking, our thesis will propose solutions that educate communities to the vital need for salt marshes both directly and regionally, to present solutions that they will accept, and to propose ways of assessing the solutions for their efficacy once they have been implemented. The Design Thinking process combines empathy to enable deep understanding and reframing of a problem, creativity to generate insights and solutions and rationality to analyze and fit solutions to the context

Marine Fungal Diversity: A Comparison of Natural and Created Salt Marshes of the North-Central Gulf of Mexico

Marine fungal communities of created salt marshes of differing ages were compared with those of two reference natural salt marshes. Marine fungi occurring on the lower 30 cm of salt marsh plants Spartina allerniflora and Juncus roemerianus were inventoried with morphological and molecular methods (ITS T-RFLP analysis) to determine fungal species richness, relative frequency of occurrence and ascomata density. The resulting profiles revealed similar fungal communities in natural salt marshes and created salt marshes 3 y old and older with a 1.5 y old created marsh showing less fungal colonization. A 26 y old created salt marsh consistently exhibited the highest fungal species richness. Ascomata density of the dominant fungal species on each host was significantly higher in natural marshes than in created marshes at all three sampling dates. This study indicates marine fungal saprotroph communties are present in these manmade coastal salt marshes as early as 1 y after marsh creation. The lower regions of both plant hosts were dominated by a small number of marine ascomycete species consistent with those species previously reported from salt marshes of the East Coast of USA

AN INTEGRATED APPROACH TO PREVENT THE EROSION OF SALT MARSHES IN THE LAGOON OF VENICE

The loss of coastal habitats is a widespread problem in Europe. To protect the intertidal salt marshes of the lagoon of Venice from the erosion due to natural and human causes which is diffusely and intensely impacting them, the European Commission has funded the demonstrative project LIFE VIMINE. LIFE VIMINE aims to protect the most interior, hard-to-access salt marshes in the northern lagoon of Venice through an integrated approach, whose core is the prevention of erosion through numerous, small but spatially-diffuse soil-bioengineering protections works, mainly placed through semi-manual labour and with low impact on the environment and the landscape. The effectiveness of protection works in the long term is ensured through routine, temporally-continuous and spatially-diffuse actions of monitoring and maintenance. This method contrasts the common approach to managing hydraulic risk and erosion in Italy which is based on large, one-off and irreversible protection actions. The sustainability of the LIFE VIMINE approach is ensured by the participatory involvement of stakeholders and the recognition that protecting salt marshes means defending the benefits they provide to society through their ecological functions, as well as protecting the jobs linked to the existence or conservation of this habitat

Do fish communities function as biotic vectors of organic matter between salt marshes and marine coastal waters?

The contribution of fish communities to organic matter (OM) fluxes, especially between salt marshes and adjacent marine coastal waters are reviewed. For this a data set fromthe bay ofMont Saint-Michel and literature is examined and discussed. In a range of macro-tidal coasts of Europe, salt marshes are only flooded at spring tides for a short time. Many animals, including fish, then invade the salt marshes through tidal creeks. They forage there for up to a few hours and swim back to sea at ebb. Meanwhile, organic matter is exported as gut content. In the 4000 ha of salt marshes of the bay of Mont Saint-Michel mullets were responsible for the export of about 8 kg of dry weight OM h

As marismas da Baía de Paranaguá: características gerais, modos de apropriação e implicações para a legislação ambiental

This review presents the current knowledge on salt marshes of Paranaguá Bay (Southem Brazil) and analyses their floristic, faunistic and physiographic differences in relation to local mangroves. Usage and traditional management of local salt marshes have received scant attention in the literature and their potential resources and ecological functions are heavily underestimated. A re-enactment of environmental law is suggested, on the basis of a comparative analysis between structural and functional attributes of local mangroves and salt marshes