The vegetation of a relict salt marsh area in the Pisan coast in the context of brackish wetlands of Tuscany

The paper presents the results of phytosociological surveys carried out in Galanchio-Cornacchiaia, a salt marsh area on the Pisan coast (northern Tuscany), which survived the agricultural reclamation. The vegetation surveys confirm the brackish features of the site, while highlighting three substantially different subareas in terms of prevailing vegetation. The phytosociological study allowed the identification of 11 marsh phytocoenoses attributable to 12 associations (Crypsidetum aculeatae; Parapholidetum filiformis; Suaedo maritimae-Salicornietum patulae; Suaedetum maritimae; Puccinellio festuciformis-Halimionetum portulacoidis; Puccinellio festuciformis-Sarcocornietum perennis; Elytrigio elongatae-Inuletum crithmoidis; Limonio narbonensis-Juncetum gerardi; Puccinellio festuciformis-Aeluropetum litoralis, Junco maritimi-Spartinetum junceae; Juncetum maritimi-acuti; Phragmitetum australis). These plant communities are referable to 3 brackish habitats and related subtypes, reported in 92/43 ECC Directive habitats. This biotope, although part of the neighboring area of the Regional Park of Migliarino San Rossore Massaciuccoli, is currently in an extremely precarious balance and threatened by the surrounding agricultural activities. The knowledge of its naturalistic peculiarities and remarkable biodiversity, can contribute to its increased protection and conservation. This study add new data to the knowledge of the brackish vegetation of Tuscany.

Investigation and assessment of ecological water resources in the salt marsh area of a salt lake: A case study of West Taijinar Lake in the Qaidam Basin, China

The water ecology of salt marshes plays a crucial role in climate regulation, industrial production, and flood control. Due to a poor understanding of water ecology and the extensive mining of salt resources, concerns are mounting about declining groundwater levels, shrinking salt marshes, and other problems associated with the simple yet extremely fragile water ecosystem of salt marshes in arid salt lake areas. This study assessed the ecological status of water resources in the downstream salt marsh area of West Taijinar Lake in the Qaidam Basin, China (2010–2018). Using data from a field investigation, the water ecosystem was divided into an ecological pressure subsystem, an environmental quality subsystem, and a socio-economic subsystem according to an analytic hierarchy process. Each subsystem was quantitatively assessed using the ecological footprint model, the single-factor index, and available data for the salt marsh area. The results showed that water resources were always in a surplus state during the study period, whose development and utilization had a safe status. Surface water had low plankton diversity with no evidence of eutrophication, but its Cl- and SO42- concentrations were too high for direct industrial water uses. Groundwater quality was classified into class V because of high salt concentrations, which could be considered for industrial use given the demand of industrial production. The socio-economic efficiency of water resources was high, as distinguished by decreased water consumption per 10,000 yuan GDP and excellent flood resistance. In conclusion, the ecological status of water resources was deemed good in the study area and this could help sustain regional development. However, since the water ecology in this area is mainly controlled by annual precipitation, it would be challenging to deal with the uneven distribution of precipitation and flood events and to make full use of them for groundwater recharge. This study provides insight into the impact of salt lake resource exploration on water ecology, and the results can be useful for the rational utilization of water resources in salt marshes in other arid areas.

A nonlinear relationship between marsh size and sediment trapping capacity compromises salt marshes’ stability

Global assessments predict the impact of sea-level rise on salt marshes with present-day levels of sediment supply from rivers and the coastal ocean. However, these assessments do not consider that variations in marsh extent and the related reconfiguration of intertidal area affect local sediment dynamics, ultimately controlling the fate of the marshes themselves. We conducted a meta-analysis of six bays along the United States East Coast to show that a reduction in the current salt marsh area decreases the sediment availability in estuarine systems through changes in regional-scale hydrodynamics. This positive feedback between marsh disappearance and the ability of coastal bays to retain sediments reduces the trapping capacity of the whole tidal system and jeopardizes the survival of the remaining marshes. We show that on marsh platforms, the sediment deposition per unit area decreases exponentially with marsh loss. Marsh erosion enlarges tidal prism values and enhances the tendency toward ebb dominance, thus decreasing the overall sediment availability of the system. Our findings highlight that marsh deterioration reduces the sediment stock in back-barrier basins and therefore compromises the resilience of salt marshes.

Effect of spalling thickness on transverse axial bearing capacity of pile foundation under different corrosion depths

The transverse and axial bearing characteristics of bridge pile foundation in salt marsh area are studied by numerical simulation. This paper mainly analyses the change of transverse and axial bearing characteristics of pile foundation caused by the change of spalling thickness of bridge foundation. The results show that the transverse and axial bearing capacity and displacement of pile foundation will be affected by the change of concrete spalling thickness under the condition of pile corrosion. When the peeling thickness is above 9.0cm, the transverse and axial bearing characteristics of pile foundation are obviously different with the change of corrosion depth of pile body. When the peeling thickness increases and the corrosion depth of the pile body is different, the negative displacement below the zero point of the first displacement of the pile body is continuously reduced, and the displacement curve above the first displacement zero point in the direction of the pile body begins to shift. When the peeling thickness reaches 15.0cm, the pile top displacement increases to 3.75mm. The research results are of great significance to the establishment of safety evaluation system of highway bridge pile foundation in alpine salt marsh area, and provide a basis for the structural design of highway bridge pile foundation in alpine salt marsh area.

Metagenome Sequencing of Prokaryotic Microbiota from Two Hypersaline Soils of the Odiel Salt Marshes in Huelva, Southwestern Spain

ABSTRACT Two 454 shotgun metagenomes were sequenced from hypersaline soil samples collected in the Odiel salt marsh area in Huelva, southwestern Spain. Analysis of contigs and 16S rRNA-related sequences showed that Halobacteria , Balneolaeota , and Bacteroidetes were the dominant groups. Rhodothermaeota and Nanohaloarchaeota were also abundant.

Anthropogenic effects and salt marsh loss in the Mondego and Mira estuaries (Portugal)

Recent decades have witnessed marked losses of coastal wetlands worldwide, but consistent data on salt marsh area are not available. The main goal of this study was to provide information on two Portuguese estuarine habitats (Mondego and Mira) over a period of four to six decades, and to assess how anthropogenic activities have altered the salt marsh ecosystem. Chronological sequences of aerial photographs covering a period of 54 yr (1947–1998) and 38 yr (1958–1995) for the Mondego and Mira estuaries, respectively, were considered for this study. Long-term changes in the Mondego estuary revealed a clear decline in the salt marsh area during the past six decades due to urban and industrial expansion. In contrast, the Mira estuary salt marshes remained almost unchanged since 1958. This ecosystem is relatively undisturbed by anthropogenic activities, and marsh variation seems to follow natural dynamics rather than being vulnerable to anthropogenic pressure. The sustainable management of salt marshes must be a priority concern to ensure the long-term viability of their ecological, economic and social capital.