Halimione Portulacoides Research Articles

Potassium uptake in the halophyte Halimione portulacoides L. Aellen

The characteristics of root K+ uptake in the halophyte Halimione portulacoides have been studied using electrophysiological techniques. Plantlets grown in the absence of both K+ and Na+ are able to take up K+ at micromolar external concentrations and root cells of these plants depolarize in response to these K+ concentrations. Depolarizations show saturation kinetics with a Km around 300μM K+. Rubidium also induces membrane depolarizations and inhibits K+ transport at low micromolar concentrations whereas Cs+ hardly depolarizes the membrane. The addition of millimolar Na+ reduces both the affinity for K+ and the maximum transport rates, and membrane potentials become more positive only when Na+ concentration reaches 300mM. Plantlets grown at high Na+ show the same effects on K+ transport but membrane potentials are maintained at highly negative values. Plantlets grown in the absence or the presence of Na+ show similar responses to different inhibitors of K+ uptake. TEA+ does not affect K+ transport, Cs+ produces a partial inhibition whereas Ba2+ completely blocks the process. Besides, the external pH does not affect K+ transport. However, NH4+ inhibits partially this process in plants grown without Na+ but has no effect on plants grown at 300mM Na+. Altogether these results point out that the transport of K+ in this species is mediated mainly by channels, most probably of the AKT-1 type, both in plants grown with or without Na+; however, the operation of potassium transporters cannot be excluded in plants grown in the absence of Na+. Cytosolic K+ activities were also measured in plantlets grown without or with 300mM Na+, showing lower values at high Na+. Calculation of the electrochemical potential gradient for K+ in these plants indicates that the transport would be passive, i.e. mediated by channels, at concentrations higher than 20μM or 120μM, in the absence or the presence of 300mM Na+, respectively.

Dendrochronology of Atriplex portulacoides and Artemisia maritima in Wadden Sea salt marshes

The study uses a rather unusual method, dendrochronology, to investigate the growth and survival of Atriplex portulacoides L. and Artemisia maritima L. on salt marshes at two field sites on the Dutch North Sea barrier islands of Terschelling and Ameland. By providing information on longevity of these typical salt-marsh shrubs, dendrochronology offers an indirect way to investigate the influence of management regime – grazing in this case – on marsh quality and areal extent. Diminishment of salt marshes is a continuing concern in the northern Netherlands. The two shrub species studied here, A. portulacoides and A. maritima, are common to salt marshes. With their extensive roots and branches, they facilitate sedimentation and stabilize salt marshes. Using dendrochronology, this study found that annual growth rings could be identified to determine shrub age and growth. In A. portulacoides these rings took the form of a narrow band of terminal parenchyma. In A. maritima they were made up of unlignified marginal parenchyma together with higher vessel density at the beginning of the growing season. Growth rings indicated that intense grazing was clearly detrimental to the survival of A. portulacoides at the Terschelling site. However, grazing facilitated survival of A. maritima at the Ameland site by reducing light and nutrient competition from grasses. No growth trends could be found, however, as the lifespan for both species is short and many other influences on shrub growth could be identified.

Maritime halophyte species from southern Portugal as sources of bioactive molecules.

Extracts of five halophytes from southern Portugal (Arthrocnemum macrostachyum, Mesembryanthemum edule, Juncus acutus, Plantago coronopus and Halimione portulacoides), were studied for antioxidant, anti-inflammatory and in vitro antitumor properties. The most active extracts towards the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical were the methanol extracts of M. edule (IC50 = 0.1 mg/mL) and J. acutus (IC50 = 0.4 mg/mL), and the ether extracts of J. acutus (IC50 = 0.2 mg/mL) and A. macrostachyum (IC50 = 0.3 mg/mL). The highest radical scavenging activity (RSA) against the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical was obtained in the ether extract of J. acutus (IC50 = 0.4 mg/mL) and H. portulacoides (IC50 = 0.9 mg/mL). The maximum total phenolic content (TPC) was found in the methanol extract of M. edule (147 mg gallic acid equivalents (GAE)/g) and in the ether extract of J. acutus (94 mg GAE/g). Significant decreases in nitric oxide (NO) production were observed after incubation of macrophages with lipopolysaccharide (LPS) and the chloroform extract of H. portulacoides (IC50 = 109 µg/mL) and the hexane extract of P. coronopus (IC50 = 98.0 µg/mL). High in vitro cytotoxic activity and selectivity was obtained with the ether extract of J. acutus. Juncunol was identified as the active compound and for the first time was shown to display selective in vitro cytotoxicity towards various human cancer cells.

Photochemical and biophysical feedbacks of C3 and C4 Mediterranean halophytes to atmospheric CO2 enrichment confirmed by their stable isotope signatures

According the latest predictions, an increase of about two times in atmospheric CO2 concentrations, is expected to occur by the end of this century. In order to understand the effects of this atmospheric composition changes on two abundant Mediterranean halophytes (Halimione portulacoides and Spartina maritima), mesocosmos trials were performed simulating two atmospheric CO2 environments (380 ppm and 760 ppm of CO2 respectively). The two chosen halophyte species present different metabolic characteristics: H. portulacoides, is a C3 specie while S. maritima is a C4 species. Distinct feedbacks were obtained for each of the studied species. Stable Isotope discrimination showed that both species showed an enhancement of the Rubisco carboxylation capacity and photosynthetic efficiency mostly due to an increase in intracellular [CO2]. In H. portulacoides CO2 fertilization induced an enhancement of ETR and a decrease in non-photochemical quenching and in dissipated energy fluxes. On the other hand the C4 grass S. maritima, already at full capacity, showed no photosynthetic enhancement. In fact this highly productive grass presented lower photosynthetic efficiencies accompanied by increases in dissipated energy fluxes mostly due to reductions in energy flux associated with the transport of reducing power throughout the quinone pool. The accumulation of reducing power led to oxidative stress, and thus the photosynthetic ability of this grass was greatly reduced. Both these feedbacks to realistic future CO2 concentrations are important consideration for in future primary productivity models, indicating a possible reduced abundance of the pioneer S. maritima and an increased biomass spreading of the sediment stabilizer H. portulacoides, inevitably affecting the morphology and function of the salt marshes imposed by these atmospheric changes, both in terms of ecosystem functioning and loss of biodiversity.

Halimione portulacoides (L.) physiological/biochemical characterization for its adaptive responses to environmental mercury exposure

This study investigates largely unexplored physiological/biochemical strategies adopted by salt marsh macrophyte Halimione portulacoides (L.) Aellen for its adaptation/tolerance to environmental mercury (Hg)-exposure in a coastal lagoon prototype. To this end, a battery of damage (hydrogen peroxide, H2O2; thiobarbituric acid reactive substances, TBARS; electrolyte leakage, EL; reactive carbonyls; osmolyte, proline) and defense [ascorbate peroxidase, APX; catalase, CAT; glutathione peroxidase, GPX; glutathione sulfo-transferase, GST; glutathione reductase, GR; reduced and oxidized glutathione (GSH and GSSG, respectively), and GSH/GSSG ratio] biomarkers, and polypeptide patterns were assessed in H. portulacoides roots and leaves at reference (R) and the sites with highest (L1), moderate (L2) and the lowest (L3) Hg-contamination gradients. Corresponding to the Hg-burdens, roots and leaves exhibited a differential modulation of damage- and defense-endpoints and polypeptide-patterns. Roots exhibiting the highest Hg-burden (at L3) failed to maintain a coordination among enzymatic-defense endpoint responses which resulted into increased oxidation of reduced glutathione (GSH) pool, lowest GSH/GSSG (oxidized) ratio and partial H2O2-metabolism. In contrast, the highest Hg-burden exhibiting leaves (at L1) successfully maintained a coordination among enzymatic-defense endpoints responses which resulted into decreased GSH-oxidation, enhanced reduced GSH pool and GSH/GSSG ratio and lower extent of damage. Additionally, increased leaf-carotenoids content with increasing Hg-burden implies its protective function. H. portulacoides leaf-polypeptides did not respond as per its Hg-burden but the roots did. Overall, the physiological/biochemical characterization of below (roots)- and above (leaves)-ground organs (studied in terms of damage and defense endpoints, and polypeptides modulation) revealed the adaptive responses of H. portulacoides to environmental Hg at whole plant level which cumulatively helped this plant to sustain and execute its Hg-remediation potential.

Light-dark O2 dynamics in submerged leaves of C3 and C4 halophytes under increased dissolved CO2: clues for saltmarsh response to climate change.

Waterlogging and submergence are the major constraints to which wetland plants are subjected, with inevitable impacts on their physiology and productivity. Global warming and climate change, as driving forces of sea level rise, tend to increase such submersion periods and also modify the carbonate chemistry of the water column due to the increased concentration of CO2 in the atmosphere. In the present work, the underwater O2 fluxes in the leaves of two abundant Mediterranean halophytes were evaluated at different levels of dissolved CO2. Photosynthetic enhancement due to increased dissolved CO2 was confirmed for both Halimione portulacoides and Spartina maritima, probably due to high tissue porosity, formation of leaf gas films and reduction of the oxygenase activity of Rubisco. Enhancement of the photosynthetic rates in H. portulacoides and S. maritima was concomitant with an increase in energy trapping and transfer, mostly due to enhancement of the carboxylation reaction of Rubisco, leading to a reduction of the energy costs for carbon fixation. Transposing these findings to the ecosystem, and assuming increased dissolved CO2 concentration scenarios, the halophyte community displays a new ecosystem function, increasing the water column oxygenation and thus reinforcing their role as principal primary producers of the estuarine system.

Accumulation des éléments traces et tolérance au stress métallique chez les halophytes colonisant les bordures de la lagune de Bizerte (Tunisie)

Accumulation of trace elements and tolerance to metal stress of the halophytes that colonize the edges of the lagoon of Bizerte (Tunisia). The lagoon of Bizerte underwent a mixed anthropic pollution, essentially enhanced by the unlimited industrial waste derived from Iron Factory “ El Fouledh”, Industrial Refining Tunisian Company, Cement Company and from 400 industrial units established around it. This waste includes major pollutants conducive to a degradation of the ecological conditions of this lagoon. Previous research dealt with most of the different ecosystem components : soil, sediments, water, and aquatic organisms. In the present study, we have been interested in the halophytes inhabiting the edges of Bizerte lagoon. This study would allow us to identify the accumulating species to be used in the programs of phytoremediation. Shoots of Atriplex portulacoides, Arthrocnemum indicum, Salicornia arabica and Suaeda fruticosa were harvested, rinsed, dried and then crushed. Analyses were focused on few trace metals : Pb, Cu, Zn and Cd. Our results have allowed us to classify the halophytes “A. portulacoides, A. indicum, S. arabica and S. fruticosa” among the accumulating species of Pb (respectively 84.6, 92.2, 102.9 and 86.3 μg. g-1 DW), of Cu (respectively 14.5, 15.1, 24.2 and 14.9 μg. g-1 DW) and of Zn (respectively 1370.1, 625.1, 1601.4 and 772.5 μg. g-1 DW). Also, A. portulacoides and S. arabica are distinguished by their ability to store significant amounts of Zn which gives them a potential utility in the remediation programs. As regards Cd, we have shown that all studied species are hyper-accumulators of this metal (A. portulacoides : 274.0 μg. g-1 DW ; A. indicum : 280.4 μg. g-1 DW ; S. arabica : 211.6 μg. g-1 DW and S. fruticosa : 209.0 μg. g-1 DW). It should be noted that the harvested halophytes do not show any sign of toxicity, and they are able to accumulate more important amounts of heavy metals and to tolerate the metallic stress. These results show that the studied halophytes can be recommended for all programs of phytoremediation in polluted and salty areas.

Screening of lipophilic and phenolic extractives from different morphological parts of Halimione portulacoides

The chemical composition of the lipophilic and phenolic extractives of the leaves, stems and roots of the salt marsh plant Halimione portulacoides from the Aveiro Lagoon was thoroughly investigated by gas chromatography–mass spectrometry (GC–MS) and ultra-high-performance liquid chromatography–mass spectrometry (UHPLC–MS), respectively. The lipophilic fraction of leaves and stems is mainly composed of long chain aliphatic acids and alcohols (both in the C16–C30 range) and smaller amounts of sterols, such as schottenol, β-sitosterol and β-sitostanol. The major component of roots extract is a triterpenic ketone, hop-17(21)-en-3-one, accounting for 2.8gkg−1 of dry material. Furthermore, thirteen phenolic compounds were firstly reported as constituents of this halophytic shrub. Among the studied plant tissues, leaves are the richest in phenolic compounds with 4.6gkg−1 of dry material, most of which correspond to sulfated flavonoids (3.1gkg−1 of dry material), particularly derivatives of isorhamnetin-sulfate.

Microdistribution of major to trace elements between roots of Halimione portulacoides and host sediments (Tagus estuary marsh, Portugal)

Aim This study presents a micrometre-scale map of the elemental distribution within roots and surrounding sediment of Halimione portulacoides of a contaminated salt marsh in the Tagus estuary.

Hydrocarbon contamination and plant species determine the phylogenetic and functional diversity of endophytic degrading bacteria.

Salt marsh sediments are sinks for various anthropogenic contaminants, giving rise to significant environmental concern. The process of salt marsh plant survival in such environment is very intriguing and at the same time poorly understood. The plant–microbe interactions may play a key role in the process of environment and in planta detoxification.In this study, a combination of culture-dependent and culture-independent molecular approaches [enrichment cultures, polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), DNA sequencing] were used to investigate the effect of petroleum hydrocarbons (PH) contamination on the structure and function[polycyclic aromatic hydrocarbon (PAH) dioxygenase genes] of endophytic bacterial communities of salt marsh plant species (Halimione portulacoides and Sarcocornia perennis)in the estuarine system Ria de Aveiro (Portugal). Pseudomonads dominated the cultivable fraction of the endophytic communities in the enrichment cultures. In a set of fifty isolates tested, nine were positive for genes encoding for PAH dioxygenases (nahAc)and four were positive for plasmid carrying genes encoding PAH degradation enzymes(nahAc). Interestingly, these plasmids were only detected in isolates from most severely PH-polluted sites. The results revealed site-specific effects on endophytic communities,related to the level of PH contamination in the sediment, and plant-species-specific ‘imprints’ in community structure and in genes encoding for PAH dioxygenases. These results suggest a potential ecological role of bacterial plant symbiosis in the process of plant colonization in urban estuarine areas exposed to PH contamination.

Growth and survival of Halimione portulacoides stem cuttings in heavy metal contaminated soils

The halophytic shrub Halimione portulacoides demonstrates a high tolerance to heavy metal contamination and a capacity for accumulating metals within its tissues. On the Iberian Peninsula, this species has colonized habitats with high levels of metal pollution. The aim of this study is to analyze the response of H. portulacoides stem cuttings to this pollution. Growth, photosynthesis and metal uptake were examined in H. portulacoides through an experiment in which stem cuttings were replanted in metal-contaminated soil. This condition decreased growth and lowered both photosynthetic rate and stomatal conductance. Reduced photosynthetic performance was largely due to the reduced concentration of photosynthetic pigments. Despite these responses, there was some important evidence suggesting the phytoremediatory potential of Halimione stem cuttings. The results of our study indicate that this salt-marsh shrub may represent a biotool of value in the restoration of polluted areas.

SPE sample pre-treatment using a mixed-mode sorbent of reverse-phase and ionic exchange for determination of ALMWOAs in waters

Studies concerning the role of aliphatic low molecular weight organic acids (ALMWOAs) in physical, chemical and biological processes occurring in rhizosphere have been carried out over the last decades. However, the analytical determination of ALMWOAs concentrations in nature is difficult owing to their considerably low levels and the interference of most environmental matrices, which demands pre-concentration steps. For these reasons, a pre-treatment of the sample prior to its analysis is usually required. Herein, a solid phase extraction (SPE) method is given as a sample pre-treatment step for ALMWOAs determination in solutions with plant exudates. A SPE sorbent, with characteristics different from those used until now, was used to overcome matrix interference. High-performance liquid chromatography (HPLC) coupled with a diode array detector (DAD) was used for analysis.Acceptable ALMWOAs recovery percentages were achieved for freshwater matrices and interference of trace metals (Cu, Cd and Ni) was not observed. The developed method was applied to identify and estimate the levels of ALMWOAs released in the solution (freshwater enriched with 10 mg/L Cu, 5 mg/L Ni and 1 mg/L Cd) where roots of Halimione portulacoides and Phragmites australis specimens have been exposed, for 2 hours. Both plants liberated measurable amounts of oxalic acid and P. australis also released into the solution citric and maleic acids.

Waterlogging affects the distribution of the saltmarsh plant Atriplex portulacoides (L.) Aellen

Atriplex portulacoides is a perennial halophyte common along northern European coasts. However it has been observed to be completely absent from peat based Ombrogenic Atlantic saltmarshes. The aim of this study was to elucidate the factors affecting the in situ distribution of A. portulacoides within saltmarsh sites including its absence on peat based saltmarshes. This was carried out through three approaches: by mapping the distribution of A. portulacoides within saltmarshes on the southwest coast of Ireland; by examining the ability of rooted cuttings of A. portulacoides to establish on peat and non-peat saltmarshes in situ; and finally by investigating experimentally the tolerance of A. portulacoides to waterlogging treatments. This study indicates that a combination of multiple abiotic and biotic factors, including intolerance to high soil moisture most likely determines the distribution of A. portulacoides.

Ecophysiological adaptations of two halophytes to salt stress: Photosynthesis, PS II photochemistry and anti-oxidant feedback – Implications for resilience in climate change

Halimione portulacoides and Sarcocornia fruticosa commonly exhibit a reddish coloration especially in high evaporation periods, due to betacyanin production in response to stress. Although sharing the same area in salt marshes, they present different strategies to overcome salinity stress. While S.fruticosa present a dilution strategy, increasing succulence, H.portulacoides appears to have developed an ionic compartmentalization strategy. Nevertheless, there's still a decrease in the photosynthetic activity in different extents. While in S.fruticosa, the impairment of photosynthetic activity is due to a decrease in the flow from the electron transport chain to the quinone pool; in H.portulacoides the process is affected far more early, with high amounts of energy dissipated at the PSII light harvesting centers. This photosynthetic impairment leads to energy accumulation and consequently to the production of reactive oxygen species (ROS). SOD was particularly active in stressed individuals, although this increment is rather more significant in S.fruticosa than in H.portulacoides suggesting that H.portulacoides may have a maximum salt concentration at which can sustain cellular balance between ROS production and scavenging. These different ecophysiological responses have great importance while evaluating the impacts climate change driven increase of sediment salinity on halophyte physiology and on the marsh community and ecosystem services.

SELECTIVE CULTURES FOR THE ISOLATION OF BIOSURFACTANT PRODUCING BACTERIA: COMPARISON OF DIFFERENT COMBINATIONS OF ENVIRONMENTAL INOCULA AND HYDROPHOBIC CARBON SOURCES

The potential of estuarine microniches as reservoirs of biosurfactant-producing bacteria was evaluated by testing different combinations of inocula and hydrophobic carbon sources. Selective cultures using diesel, petroleum, or paraffin as hydrophobic carbon sources were prepared and inoculated with water from the surface microlayer, bulk sediments, and sediment of the rhizosphere of Halimione portulacoides. These inocula were compared regarding the frequency of biosurfactant-producing strains among selected isolates. The community structure of the selective cultures was profiled using denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA gene fragments at the end of the incubation. The DGGE profiles corresponding to the communities established in selective cultures at the end of the incubation revealed that communities were different in terms of structural diversity. The highest diversity was observed in the selective cultures containing paraffin (H ' = 2.5). Isolates were obtained from the selective cultures (66) and tested for biosurfactant production by the atomized oil assay. Biosurfactant production was detected in 17 isolates identified as Microbacterium, Pseudomonas, Rhodococcus, and Serratia. The combination of estuarine surface microlayer (SML) water as inoculum and diesel as carbon source seems promising for the isolation of surfactant-producing bacteria. Supplemental materials are available for this article. Go to the publisher's online edition of Preparative Biochemistry and Biotechnology to view the supplemental file.

Ranking of 11 coastal halophytes from salt marshes in northwest Turkey according their salt tolerance

Salt-affected soils with high electrolyte contents limit the development of the majority of plants and serve as a habitat only for such species (halophytes) that can survive the conditions. To date, there is still much that is unknown about the physiological mechanisms, including ion relationships, that make plants salt-resistant. The primary aim of this study was to evaluate a method of ranking plants for their salt tolerance. A total of 11 coastal halophytes of the Kavak Delta were evaluated for their ability to cope with different soil salinities. For this, electrical conductivities of soils (of up to 135 dS m^{-1}) were recorded and a total of 100 plant samples, including plant roots, were taken from a depth of 0-15 cm in the soil. The halophytes were ranked in the following order from highest to moderate salt tolerance: Halocnemum strobilaceum >= Salicornia fragilis >= Arthrocnemum fruticosum = Suaeda prostrata >= Salsola kali = Petrosimonia brachiata >= Juncus maritimus = Aeluropus littoralis >= Halimione portulacoides = Limonium graecum >= Artemisia santonicum. The Na^{+}/K^{+} ratios of leaves perfectly reflected the salinity tolerance ranking of all halophytic species examined. It proved possible to rank the salt tolerance of halophytes by assessment of the electrical conductivity of the soil in which they grew naturally; tolerance was well predicted by the Na^{+}/K^{+} ratio in the shoots.

Halophyte anti-oxidant feedback seasonality in two salt marshes with different degrees of metal contamination: search for an efficient biomarker.

Salt marshes can be affected by metal contamination when near a polluted area, and this excessive concentration of metals is a source of stress in plants. Production of proteins, flavonoids, phenolic compounds and anti-oxidant feedback can be used as biomarkers, as well to assess the suitability of halophytes to function as a biomonitors. Through monitoring the anti-oxidative feedback in Halimione portulacoides (L.) Aellen, Sarcocornia fruticosa (L.) A.J.Scott and Spartina maritima (Curtis) Fernald in a contaminated and non-contaminated marsh, S. maritima seems to have potential as a bioindicator species, showing different biochemical characteristics according to the degree of contamination to which it is exposed. The evident biochemical separation between individuals from contaminated and non-contaminated salt marshes is mostly due to differences in the activity of SOD as well APx and GPx. Without neglecting the need for further works, the present study suggests that S. maritima enzymatic defences as good candidates for efficient biomarkers for estuarine sediment quality assessment studies.

Salt Marshes on Substrate Enriched in Organic Matter: The Case of Ombrogenic Atlantic Salt Marshes

Ombrogenic Atlantic salt marshes are defined as areas of halophytic, terrestrial vegetation which are periodically flooded by the tide and have a predominant underlying organic substrate comprising of wood and/or Sphagnum peat that formed under freshwater conditions. The objective of this study was to determine to what extent salt marsh plant ecology and, specifically, vegetation composition and zonation relate to this underlying substrate of organic matter (peat). A vegetation survey was carried out on nine salt marshes, three on peat substrate and two on sand, mud and sand/mud, respectively. In parallel, key edaphic variables were measured including pH, conductivity, organic content, moisture content and nutrients: ammonium, nitrate and phosphorus. Salt marshes on peat substrate are distinct. Ammonium content was twice the maximum reported in other salt marsh studies, while the vegetation composition of salt marshes on peat substrate was significantly different from that of other salt marshes. Salt marshes on peat substrate were found to be higher in species diversity and richness and characterised by a predominantly forb and rush community. However, some common salt marsh species, such as Atriplex portulacoides and Spartina anglica were absent from salt marshes on peat. Ordination analysis revealed that zonation was primarily associated with conductivity on peat substrates. In contrast, moisture plays a greater role in zonation within non-peat salt marshes. The findings confirm that the high organic matter content of ombrogenic Atlantic salt marshes is associated with distinct vegetation composition.

Description of Meloidoderita salina sp. n. (Nematoda, Sphaeronematidae) from a micro-tidal salt marsh at Mont-Saint-Michel Bay in France

Meloidoderita salina sp. n. is described and illustrated from the halophytic plant Atriplex portulacoides L. (sea purslane) growing in a micro-tidal salt marsh in the Mont-Saint-Michel Bay in France. This new species is the first member of Meloidoderita Poghossian, 1966 collected from a saline environment, and is characterized by the following features: sedentary mature females having a small swollen body with a clear posterior protuberance; slightly dorsally curved stylet, 19.9 µm long, with posteriorly sloping knobs; neck region irregular in shape and twisted; well developed secretory-excretory (S–E) pore, with markedly sclerotized S-E duct running posteriorly; prominent uterus bordered by a thick hyaline wall and filled with eggs. The adult female transforms into a cystoid. Eggs are deposited in both egg-mass and cystoid. Cystoids of Meloidoderita salina sp. n. display a unique sub-cuticular hexagonal beaded pattern. Male without stylet, pharyngeal region degenerated, S-E duct prominent, deirids small, developed testis 97.5 µm long, spicules 18.4 µm long, cloacal opening ventrally protruded, small phasmids posterior to cloaca opening and situated at 5.9 (3.2–7.7) µm from tail end, and conical tail ending in a rounded terminus marked with one (rarely two) ventrally positioned mucro. Additionally, some young malesof the new species were observed enveloped in the last J2 cuticle. Second-stage juvenile body 470 µm long, with a 16.4 µm long stylet, prominent rounded knobs set off from the shaft, hemizonid anterior and adjacent to S-E pore, small deirids located just above S-E pore level, genital primordium located at 68–77% of body length, phasmids small and located at about 19 µm from tail tip, and tail 38.7 µm long, tapering to finely pointed terminus with a finger-like projection. Phylogenetic analyses based on the nearly full length small subunit ribosomal DNA sequences of Meloidoderita salina sp. n. revealed a close relationship of the new species with Sphaeronema alni Turkina & Chizhov, 1986 and placed these two species sister to the rest of Criconematina.

Does managed coastal realignment create saltmarshes with ‘equivalent biological characteristics’ to natural reference sites?

Summary Coastal saltmarshes provide distinctive biodiversity and important ecosystem services, including coastal defence, supporting fisheries and nutrient cycling. However, c. 50% of the world's coastal marshes are degraded or have been lost, with losses continuing. In both Europe and North America, there is a legal requirement to create habitats to substitute for losses. How well do created habitats replicate natural salt marshes? We compared plant communities and environmental characteristics of 18 deliberately realigned (managed realignment, MR ‐ between 1 and 14 years old), 17 accidentally realigned (AR, 25–131 years old) sites with those on 34 natural reference saltmarshes in the UK. Halophytic species colonized individual realignment sites rapidly, attaining species richness similar to nearby reference marshes after 1 year. Nevertheless, the community composition of MR sites was significantly different from reference sites, with early‐successional species remaining dominant, even on the high marsh. The dominance of pioneer species on the low and mid‐marsh may be because, at the same elevation, sediments were less oxygenated than on reference sites. Sediments were well oxygenated on the high marsh, but were often drier than on natural marshes. Overall community composition of AR marshes was not significantly different to reference marshes, but the characteristic perennials Limonium vulgare, Triglochin maritima, Plantago maritima and Armeria maritima remained relatively rare. In contrast, the shrub Atriplex portulacoides was more abundant, and its growth form may inhibit or delay colonization by other species. Synthesis and applications. Marshes created by managed realignment do not satisfy the requirements of the EU Habitats Directive. Adherence to the Directive might be improved by additional management interventions, such as manipulation of topographic heterogeneity or planting of mid‐ and upper‐marsh species. However, given the inherent variation in natural saltmarshes and projected environmental change, policies that require exact equivalence at individual sites may be unachievable. More realistic goals might require minimum levels of a range of ecosystem functions on a broader scale, across catchments or regions.