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The article offers information on the International Day for the Defense of Mangroves due to the substantial loss of these coastal ecosystems that are highly productive. Topics discussed include shrubs or small trees that grow in saline coastal or brackish waters; salt-tolerant trees, also called halophytes, adapted to life in adverse coastal conditions; great environmental and socioeconomic value of mangroves; and Laguncularia racemosa provide shelter and food for marine fauna.

Large influx of excess nutrients into sub-tropical brackish-water habitats is expected to radically affect the algal populations in the heavily populated Sunderbans brackish-water ecozone. Twelve selected brackish-water sites in the Indian Sunderbans were surveyed to investigate the growth performance of mat-forming dominant algal/cyanobacterial macrophytes and their potential for carbon (C) sequestration into hydrologic and pedologic pools. The mats were dominated by particular taxa at different seasons related to physico-chemical properties of the wetland habitats. Different environmental variables and biomass productivity parameters were measured on fortnightly basis to assess the carbon cycle related to dominant algal blooms of the study area. The dominating species at the twelve sites included seven genera ( Spirogyra , Rhizoclonium , Ulva , Cladophora , Pithophora , Chaetomorpha ) belonging to Chlorophyta, three genera ( Polysiphonia , Gracilaria , Catenella ) belonging to Rhodophyta and Lyngbya majuscula from cyanobacteria. Multivariate statistical methods indicated that nutrient availability, particularly dissolved P concentration and N:P ratio in the water column, along with salinity in the water column mainly affected biomass yield and C sequestration of mat-forming macrophytes and OC input into water column. However, OC contents of underlying muck proved to be very stable, though small influxes of OC occurred at each bloom. High biomass yields (34–3107 g/m 2 ) of the dominant mat components accumulated enormous stocks of OC, very little of which reaches the pedologic pool. This transient biomass might be utilized as dietary supplements or biofuel feedstocks. Availability of important dietary fatty acids in Spirogyra punctulata , Gracilaria sp., Polysiphonia mollis , Rhizoclonium riparium , R. tortuosum , Pithophora oedogonia and Ulva lactuca was considered as suitability of these species as nutraceuticals. Fatty acid compositions of L. majuscula , Catenella repens, R. tortuosum and Cladophora crystallina were estimated to be applicable for producing biodiesel for usage in sub-tropical climates. [ABSTRACT FROM AUTHOR]

Grapevine rootstocks that can absorb brackish water and maintain satisfactory growth of the grapevine scion might be a feasible management practice in areas suffering scarce water resources. The objective of this study was to evaluate the expression of antioxidant genes in 'Superior Seedless' leaves grafted on R110 (Vitis berlandieri x V. rupestris), 41B (V. berlandieri x V. vinifera) and P1103 (V. berlandieri x V. rupestris) in response to diluted brackish water irrigation at three levels: 1.5, 3.0 and 5.0 dS m-1 in addition to the 0.8 dS m-1 control. Results revealed that after salinity exposure for two weeks, the transcript levels of APX, Mn-SOD and MDAR increased in 'Superior Seedless' leaves grafted on the different rootstocks. However, their expression levels in response to salinity were noticeably higher in plants grafted on P1103 and R110 compared to 41B. The expression of CAT gene showed obvious enhanced level in plants grafted on P1103 in response to salt exposure. Meanwhile, the expression of CAT gene in 'Superior Seedless' scion grafted on 41B or R110 showed almost unchanged level in control and stressed conditions. Down-regulation of CuZn-SOD was recorded in leaves of 'Superior Seedless' grafted on P1103. Slight up-regulation of this gene in response to saline condition was recorded when scion was grafted on 41B or R110. The expression of GPX was enhanced in scion grafted on P1103 and 41B. On the other hand, scion grafted on R110 showed decreased expression of GPX in response to salt treatment. Grapevine rootstocks that have V. rupestris and V. berlandieri in their parentage are good candidates for salinity tolerance. [ABSTRACT FROM AUTHOR]

We have performed an extensive study on the responses to salt stress in four related Limonium halophytes with different geographic distribution patterns, during seed germination and early vegetative growth. The aims of the work were twofold: to establish the basis for the different chorology of these species, and to identify relevantmechanisms of salt tolerance dependent on the control of ion transport and osmolyte accumulation. Seeds were germinated in vitro, in the presence of increasing NaCl concentrations, and subjected to "recovery of germination" tests; germination percentages and velocity were determined to establish the relative tolerance and competitiveness of the four Limonium taxa. Salt treatments were also applied to young plants, by 1-month irrigation with NaCl up to 800 mM; then, growth parameters, levels of monovalent and divalent ions (in roots and leaves), and leaf contents of photosynthetic pigments and common osmolytes were determined in control and stressed plants of the four species. Seed germination is the most salt-sensitive developmental phase in Limonium. The different germination behavior of the investigated species appears to be responsible for their geographical range size: L. narbonense and L. virgatum, widespread throughout the Mediterranean, are the most tolerant and the most competitive at higher soil salinities; the endemic L. santapolense and L. girardianum are the most sensitive and more competitive only at lower salinities. During early vegetative growth, all taxa showed a strong tolerance to salt stress, although slightly higher in L. virgatum and L. santapolense. Salt tolerance is based on the efficient transport of Na+ and Cl- to the leaves and on the accumulation of fructose and proline for osmotic adjustment. Despite some species-specific quantitative differences, the accumulation patterns of the different ions were similar in all species, not explaining differences in tolerance, except for the apparent activation of K+ transport to the leaves at high external salinity, observed only in the most tolerant L. narbonense and L. virgatum. This specific response may be therefore relevant for salt tolerance in Limonium. The ecological implications of these results, which can contribute to a more efficient management of salt marshes conservation/regeneration programs, are also discussed. [ABSTRACT FROM AUTHOR]

Wittrockiella is a small genus of filamentous green algae that occurs in habitats with reduced or fluctuating salinities. Many aspects of the basic biology of these algae are still unknown and the phylogenetic relationships within the genus have not been fully explored. We provide a phylogeny based on three ribosomal markers (ITS, LSU, and SSU rDNA) of the genus, including broad intraspecific sampling for W. lyallii and W. salina, recommendations for the use of existing names are made, and highlight aspects of their physiology and life cycle. Molecular data indicate that there are five species of Wittrockiella. Two new species, W. australis and W. zosterae, are described, both are endophytes. Although W. lyallii and W. salina can be identified morphologically, there are no diagnostic morphological characters to distinguish between W. amphibia, W. australis, and W. zosterae. A range of low molecular weight carbohydrates were analyzed but proved to not be taxonomically informative. The distribution range of W. salina is extended to the Northern Hemisphere as this species has been found in brackish lakes in Japan. Furthermore, it is shown that there are no grounds to recognize W. salina var. kraftii, which was described as an endemic variety from a freshwater habitat on Lord Howe Island, Australia. Culture experiments indicate that W. australis has a preference for growth in lower salinities over full seawater. For W. amphibia and W. zosterae, sexual reproduction is documented, and the split of these species is possibly attributable to polyploidization. [ABSTRACT FROM AUTHOR]

Requirement of reverse osmosis (RO) process at places facing energy and water quality problem makes its assessment and optimization vital while considering recovery, rejection as well as specific energy consumption. In the present paper, three thin film composite (TFC) RO membranes (make: CSM, Dow and Vontron) in spiral wound (SW) configuration have been chosen to study their relative performance. Comparative study of RO membranes was conducted using experimental observations supported by membrane characterization. Optimization experiments were performed using central composite design (CCD) of response surface methodology (RSM). Four input variables viz. feed water pH, temperature, pressure and concentration were optimized and interaction between them was observed, while, recovery, rejection and specific energy consumption (SEC) were taken as response attributes. The experiments conducted employing the optimized input values validated the developed RSM model. Predictive model using multiple response optimization revealed the optimal efficiency of CSM RO membrane at 6.53 pH, 1500 mg/L concentration, 0.78 MPa pressure and 31.94oC temperature producing 19.25% water recovery, 89.21% salt rejection and 17.60 kWh/m3 SEC, respectively. Membrane surface characterization was carried out by FE-SEM, AFM, contact angle measurement and FTIR. The lesser contact angle and smoother surface apparently contributed to the better performance of CSM RO membrane. This paper may demonstrate a simple method for optimizing the commercially available small scale RO membranes. [ABSTRACT FROM AUTHOR]

Several reports have highlighted that many plant growth-promoting endophytic bacteria (PGPE) can assist their host plants in coping with various biotic and abiotic stresses. However, information about the PGPE colonizing in the halophytes is still scarce. This study was designed to isolate and characterize PGPE from salt-accumulating halophyte Salicornia europaea grown under extreme salinity and to evaluate in vitro the bacterial mechanisms related to plant growth promotion. A total of 105 isolates were obtained from the surface-sterilized roots, stems, and assimilation twigs of S. europaea. Thirty-two isolates were initially selected for their ability to produce 1-aminocyclopropane-1-carboxylate deaminase as well as other properties such as production of indole-3-acetic acid and phosphate-solubilizing activities. The 16S rRNA gene-sequencing analysis revealed that these isolates belong to 13 different genera and 19 bacterial species. For these 32 strains, seed germination and seedling growth in axenically grown S. europaea seedlings at different NaCl concentrations (50-500 mM) were quantified. Five isolates possessing significant stimulation of the host plant growth were obtained. The five isolates were identified as Bacillus endophyticus, Bacillus tequilensis, Planococcus rifietoensis, Variovorax paradoxus, and Arthrobacter agilis. All the five strains could colonize and can be reisolated from the host plant interior tissues. These results demonstrate that habitat-adapted PGPE isolated from halophyte could enhance plant growth under saline stress conditions. [ABSTRACT FROM AUTHOR]

High-throughput sequencing technology was used to reveal the composition and distribution of fungal community structure in the Yellow River Delta under bare land and four kinds of halophyte vegetation ( saline seepweed, Angiospermae, Imperata and Apocynum venetum [ A. venetum]). The results showed that the soil quality continuously improved with the succession of salt vegetation types. The soil fungi richness of mild-salt communities ( Imperata and A. venetum) was relatively higher, with Shannon index values of 5.21 and 5.84, respectively. The soil fungi richness of severe-salt-tolerant communities ( saline seepweed, Angiospermae) was relatively lower, with Shannon index values of 4.64 and 4.66, respectively. The UniFrac metric values ranged from 0.48 to 0.67 when the vegetation was in different succession stages. A total of 60,174 valid sequences were obtained for the five vegetation types, and they were classified into Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota and Mucoromycotina. Ascomycota had the greatest advantage among plant communities of Imperata and A. venetum, as indicated by relative abundances of 2.69 and 69.97 %, respectively. Basidiomycota had the greatest advantage among mild-salt communities of saline seepweed and Angiospermae, with relative abundances of 9.43 and 6.64 %, respectively. Soil physical and chemical properties were correlated with the distribution of the fungi, and Mucor was significantly correlated with soil moisture ( r = 0.985; P < 0.01). Soil quality, salt vegetation and soil fungi were influenced by each other. [ABSTRACT FROM AUTHOR]

Background: Soil salinity affects growth and yield of crop plants. Plants respond to salinity by physiological and biochemical adjustments through a coordinated regulation and expression of a cascade of genes. Recently, halophytes have attracted attention of the biologists to understand their salt adaptation mechanisms. Spartina alterniflora (smooth cordgrass) is a Louisiana native monocot halophyte that can withstand salinity up to double the strength of sea water. To dissect the molecular mechanisms underlying its salinity adaptation, leaf and root transcriptome of S. alterniflora was sequenced using 454/GS-FLX. Results: Altogether, 770,690 high quality reads with an average length 324-bp were assembled de novo into 73,131 contigs (average 577-bp long) with 5.9X sequence coverage. Most unigenes (95 %) annotated to proteins with known functions, and had more than 90 % similarity to rice genes. About 28 % unigenes were considered specific to S. alterniflora. Digital expression profiles revealed significant enrichment (P < 0.01) of transporters, vacuolar proton pump members and transcription factors under salt stress, which suggested the role of ion homeostasis and transcriptional regulation in the salinity adaptation of this grass. Also, 10,805 SSRs markers from 9457 unigenes were generated and validated through genetic diversity analysis among 13 accessions of S. alterniflora. Conclusions: The present study explores the transcriptome of S. alterniflora to understand the gene regulation under salt stress in halophytes. The sequenced transcriptome (control and salt-regulated) of S. alterniflora provides a platform for further gene finding studies in grasses. This study and our previously published studies suggested that S. alterniflora is a rich reservoir of salt tolerance genes that can be used to develop salt tolerant cereal crops, especially rice, a major food crop of global importance. [ABSTRACT FROM AUTHOR]

This study investigates the temporal impacts of climate change on rice yield for summer-autumn (SA) and autumn-winter (AW) cropping pattern along with implication of brackish irrigation water for the SA season. Furthermore, evaluation of different agro-adaptations to overcome negative impacts of climate change was also done for Ca Mau province of Vietnam. Climatic variables were derived from six general circulation models which were further bias corrected at Ca Mau city station for three future time periods (2025s, 2055s, and 2085s). Calibrated AquaCrop 4.0 was used to project the future rice yield under climate change and different salinity levels in irrigation water. Simulation shows a decline in rice yield ranging from 1.60 to 23.69 % and 8.06 to 20.15 % by 2085s relative to baseline climate for A2 and B2 scenarios respectively in the case of the SA cropping season. However, an increase in rice yield ranging from 3.29 to 12.35 % and 6.64 to 17.23 % is observed for the corresponding time period and scenarios. Further simulations for the SA cropping season under climate change and increasing salinity in irrigation water suggest an insignificant increase in yield relative to the yield obtained without irrigation. Moreover, proper management practices, namely forward and early shifts in transplanting dates along with increasing fertilizer application rates, are observed to be beneficial to enhance the rice yield under climate change. [ABSTRACT FROM AUTHOR]

Three different Tamarix species, namely Tamarix aphylla, T. aphylla “Erect”-type and Tamarix jordanis, were grown in an experimental field under extreme desert conditions and irrigated with either reclaimed sewage or brackish water. Depending on both species and source of irrigation, the above-ground biomass production ranged from 18 to 36 Mg ha−1 in the first year. Among the three chemically characterized Tamarix species, T. jordanis was selected due to its higher cellulose content, and lower hemicellulose and phenol contents so as to outline a preliminary process flow sheet for ethanol production. This included steam-injection heating under acidic conditions (200 °C; 90 s; 0.5% H2SO4; 160 g L−1 solid loading) using a novel lab-scale Direct Steam Injection Apparatus, enzymatic saccharification (50 °C; pH 5.0; 200 g L−1 solid loading; 20 FPU g−1 cellulose) and subsequent ethanolic fermentation (30 °C; Saccharomyces cerevisiae F-15 as the inoculum). Lab-scale fermentation runs were carried out in a 3-L stirred bioreactor in repeated-batch mode and showed an almost quantitative conversion of glucose into ethanol (0.507 ± 0.006 g g−1), thus leading to a satisfactory overall process ethanol yield of about 145 L Mg−1 Tamarix biomass. [ABSTRACT FROM AUTHOR]

In wetland soils and underwater sediments of marine, brackish and freshwater systems, the strong phytotoxin sulfide may accumulate as a result of microbial reduction of sulfate during anaerobiosis, its level depending on prevailing edaphic conditions. In this review, we compare an extensive body of literature on phytotoxic effects of this reduced sulfur compound in different ecosystem types, and review the effects of sulfide at multiple ecosystem levels: the ecophysiological functioning of individual plants, plant-microbe associations, and community effects including competition and facilitation interactions. Recent publications on multi-species interactions in the rhizosphere show even more complex mechanisms explaining sulfide resistance. It is concluded that sulfide is a potent phytotoxin, profoundly affecting plant fitness and ecosystem functioning in the full range of wetland types including coastal systems, and at several levels. Traditional toxicity testing including hydroponic approaches generally neglect rhizospheric effects, which makes it difficult to extrapolate results to real ecosystem processes. To explain the differential effects of sulfide at the different organizational levels, profound knowledge about the biogeochemical, plant physiological and ecological rhizosphere processes is vital. This information is even more important, as anthropogenic inputs of sulfur into freshwater ecosystems and organic loads into freshwater and marine systems are still much higher than natural levels, and are steeply increasing in Asia. In addition, higher temperatures as a result of global climate change may lead to higher sulfide production rates in shallow waters. [ABSTRACT FROM AUTHOR]

Abstract: Desalination practice presented by desalination plants'' performance is an attractive area in which researchers investigate and contribute to both plant improvement and desalination research and development fields. Six large BWDPs and one SW desalination plant are operating in Gaza and providing 4% of the total water demand of the Gaza population. Most of the drinking water is produced through small private plants and RO housing units. The six BWDPs were investigated and assessed in terms of operational conditions and feed and permeate quality towards estimating the essential improvements required and their performance significance. The quality of plant feed was found to be noncompliant with WHO and Palestinian Standards Institute in most cases which is in contrast with the permeate of all plants. The assessment made through this study assists in the better understanding of the current situation of these plants in Gaza and recommending the essential improvements needed to increase their water production without increasing abstraction. In addition, the multi criteria analysis used to evaluate BWDP performance may assist in prioritizing the application of improvements. [Copyright &y& Elsevier]

Abstract: Wetland dynamic in the northern Brazilian Amazon region during the Holocene was reviewed using palynological, carbon and nitrogen isotopes records, and C/N ratio previously published. The integration of 72 radiocarbon dates recorded in 34 sediment cores sampled along the marine and fluvial littoral, and mainly influenced by the Amazon River, reveals that marine influence and mangrove vegetation were wider than today on the mouth of Amazon River between >8990–8690 and 2300–2230 cal yr BP, forming a continuous mangrove belt along the northern Brazilian Amazon littoral. The establishment of this mangrove strip is a direct consequence of the marine incursion caused by post-glacial sea-level rise possibly associated with tectonic subsidence during the Early and Middle Holocene. In the Late Holocene, in areas influenced by the Amazon River discharge, the mangroves were replaced by freshwater vegetation, and the coast morphology evolved from an estuarine dominated into a rectilinear coast due to coastal progradation. Nevertheless, the marine-influenced littoral, which is currently dominated by mangroves and salt-marsh vegetation, has persistently had brackish water vegetation over tidal mud flats throughout the entire Holocene. Likely, the fragmentation of this continuous mangrove line during the Late Holocene was caused by the increase of river freshwater discharge associated to the change from dry into wet climates in the Late Holocene. This caused a significant decrease of tidal water salinity in areas near the mouth of Amazon River. These changes in the Amazon discharge are probably associated with dry and wet periods in the northern Amazon region during the Holocene. [Copyright &y& Elsevier]

Abstract: The effect of canopy removal, a form of non-lethal disturbance, was assessed for the interaction between two co-occurring American East Coast salt marsh angiosperms, Schoenoplectus americanus (Pers.) Volkart ex Schinz and R. Keller and Distichlis spicata (L.) Greene, in a greenhouse replacement series experiment. In mixture, aboveground production of S. americanus was significantly higher than production of D. spicata. When plant canopy was experimentally removed, this difference was stronger (366±35gm−2 vs. 139±41gm−2; P =0.0033) than when it was left intact (383±44gm−2 vs. 215±67gm−2; P =0.07). Belowground yield of S. americanus was significantly higher than yield of D. spicata (113±27gm−2 vs. 57±20gm−2; P =0.047) in pots with canopy removal. In control pots, there was no significant difference between the belowground yields of the two species (P =0.23). Comparisons of relative yields of the two species (based on biomass and stem density measurements) indicated that S. americanus suppressed D. spicata when the plant canopy was removed. This suggests that canopy disturbance gives S. americanus a competitive advantage over D. spicata in mixed compositions. Anthropogenic disturbances such as prescribed fire and grazing used as land management techniques are likely to influence competitive interactions and play a key role in plant community productivity. [Copyright &y& Elsevier]

During a limnological and palaeolimnological study of the western part of the Great Coast of Senegal, an analysis of diatoms was carried out in Thiaroye Pond in the suburbs of Dakar. Current diatom flora in the water and on floating plants, and subfossil flora in two cores were sampled in 1996 and 2003. A total of 104 species and varieties, belonging to 38 genera were identified, 61 in the current environment and 87 from the cores. The genera most represented were Nitzschia (16 species), Eunotia (9 species), Amphora and Pinnularia (7 species each). The most frequently and regularly observed freshwater species were Cyclotella meneghiniana, Diadesmis confervacea, Eunotia pectinalis and Nitzschia amphibia, with marine to brackish-water forms occasionally being present. The proximity of the pond to the Atlantic Ocean had a dual effect on the diatom assemblage. Marine to brackish-water diatoms were transferred by wind and birds, and salinity increased over time, due to the rising level of saline groundwater. The alkalinity of the pond increased over time, due to the progressive destruction of the natural vegetation of the pond as a consequence of cultivation. [ABSTRACT FROM AUTHOR]

With more pressing demands for non-agricultural sectors, availability of good-quality water is falling short of the crop water requirement, particularly in arid and semi-arid regions of the world, like Pakistan. Studies were conducted at three sites following randomized complete block design (RCBD) with three replications. The treatments employed were: Tube well water (TW) alone; TW + Gypsum @ 50% soil gypsum requirement (TW + G50); TW-Canal water (CW) + G50; TW-CW + farm manure (FM) @ 25 Mg ha-1 (TW-CW + FM) before sowing wheat. After the harvest of wheat 2008-09, non-significant decrease in bulk density was recorded with applied treatments while infiltration rate remained unchanged. There was maximum and significant decrease in ECe and SAR with TW-CW + FM at all the three sites. Maximum decrease in ECe (72.65%) at 0-15 cm soil depth was at site 2, while maximum decrease in ECe (77.62%) at 15-30 cm soil depth was at site 1. Maximum percent decrease in SAR was 75.76% at 0-15 cm followed by 63.93% at15-30 cm at sites 2 and 3, respectively, with TW-CW + FM. Maximum wheat grain yields (3656, 3531 and 3826 kg ha-1) and straw yields (4826, 4624 and 4707 kg ha-1) were recorded at sites 1, 2 and 3, respectively, with TW-CW + FM. The net benefit was maximum with TW-CW + FM at all the three sites. [ABSTRACT FROM AUTHOR]

Abstract: Charophytes are unique and endangered macroalgae. Mechanical stress is known to damage charophyte communities, however, virtually nothing is known how such disturbance affect seasonal succession and recovery of charophyte communities. We examined the response of a shallow water charophyte community to different types and timing of disturbances by conducting seasonal in situ field experiment in a brackish water ecosystem. The disturbances associated with mechanical removal of vegetation or sediment had the largest impact on the charophyte community. Disturbances that only partly damaged the plants had minor effects and communities were characterized by fast recovery. The timing of disturbance had significant effects on the charophyte community with stronger effects when disturbed at the early stage compared to mid-stage of seasonal succession. [Copyright &y& Elsevier]

The article presents a study which aims to find out if small lacunae jellyfish Odessia maeotica acts as a top predator that exhibits direct and indirect control on plankton communities. The study carried out a short-term field experiment using tanks in a Mediterranean brackish lagoon in the wetlands of Empordà located at the North East (NE) of Iberian Peninsula. It compares the structures of plankton in the presence and absence of jellyfish. The results show that the composition of plankton changes in the presence of O. maeotica through top-down effects. Moreover, the relative abundance of phytoplankton species also changes, however, net increase in the phytoplankton biomass was not found.

Abstract: Studies conducted in terrestrial ecosystems have shown that increasing plant diversity enhances ecosystem processes such as primary production. In marine systems, knowledge of how plant diversity influences ecosystem processes and higher trophic levels is still limited. To examine how plant richness and composition influence recruitment and colonization processes, defaunated eelgrass (Zostera marina), sago pondweed (Potamogeton pectinatus) and perfoliate pondweed (Potamogeton perfoliatus) were planted on an unvegetated, sandy bottom in all possible combinations in July and August. Both field experiments lasted 1week. Our results showed that in these plant assemblages plant richness had a negative effect on faunal diversity (H′) and evenness (J′), while total abundance showed strong temporal variation with weak, positive relationships with plant species richness in both August and July. Plant species composition had strong effects on amphipods (Gammarus spp.), thus both the abundance and biomass were higher in treatments containing P. perfoliatus. The colonization process was significantly influenced by the numerical dominance of a few faunal species, e.g. the settlement of lagoon cockles (Cerastoderma glaucum), and by the timing of the experiments. The results indicate that faunal colonization in these communities is rapid and significantly influenced by the traits of particular plant species. [Copyright &y& Elsevier]

The article presents a study on how plant diversity affects primary production and species interactions within brackish water angiosperm communities. It says that a 14 week experiment was conducted to investigate the influence of plant species composition and richness on plant productivity in such ecosystems. The study found a trend of positive complementary and negative selection effects despite the absence of vital plant variable and treatment results. It suggests that plant diversity had no apparent effect on the concentrations of sediment porewater nutrients, which signifies weak richness effects on resource use.

Qualitative and quantitative compositions of esterified fatty acids (FAs) in the total lipids from the leaves, shoots, and roots of halophile plants, such as suaeda ( Suaeda altissima), samphire ( Salicornia europaea), and wormwood ( Artemisia lerchiana), collected in their natural environments were estimated by GLC techniques. It was shown that the vegetative organs of these halophytes contained 24 FA species, and 16 of them were tentatively identified as the very-long-chain FAs (VLCFAs). There were four VLCFA groups, viz. C20, C21, C22, and C23, each including saturated, mono-, and diunsaturated components; C24 and C25 FAs were also present. The concentration of VLCFAs in the total FAs comprised 4–64%. In vegetative organs of higher plants not subjected to genetic transformation, such a high VLCFA content was found for the first time. Saturated and even-numbered components predominated among the VLCFAs, and the roots exceeded severalfold the above-ground organs in the total VLCFA content. Possible pathways of VLCFA biosynthesis in plants, VLCFA content in the vegetative tissues, and the physiological role of membrane lipid FA composition in the plant salt metabolism are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Possible reproductive isolation between freshwater and brackish water populations of the dioecious charophyte Chara aspera was studied by means of cross-fertilization experiments and AFLP (Amplified Fragment Length Polymorphism). Three Swedish freshwater populations and three (German and Swedish) Baltic Sea populations of C. aspera were sampled. Cross-fertilization experiments were performed in a full combination setup of all populations and with two different salinities (0 and 10PSU). Both freshwater and brackish water females formed about 70% more gametangia at 0 than at 10PSU. Male individuals collected from freshwater had higher fertility than brackish water males at both salinities. 57% of all gametangia of females from freshwater developed into oospores compared to only 8% of gametangia of brackish water females. 42% of all oospores were fertilized in crosses between habitats (freshwater–brackish water) compared to 36% in crosses within habitats, the difference was not significant. Oospore and bulbil germination was investigated using propagules from freshwater and brackish water populations and incubation salinities of 0, 5, 10 and 20PSU. None of the oospores collected from brackish water germinated. Germination of oospores and bulbils from freshwater was higher at 0 and 5PSU than at higher salinities. Only around 40% of bulbils from brackish water germinated at 20PSU compared to around 70% at the other three salinities. Germination of all bulbils was delayed at 20PSU compared to other salinities. Genetic similarities (Jaccard indices of AFLP data) were higher within than between populations, but comparisons within habitat (freshwater–freshwater and brackish water–brackish water) were not different from comparisons between habitats. Our results did not identify any reproductive isolation between freshwater and brackish water populations, but indicate low gene flow between the two habitats. Oospore and bulbil germination success were highest at salinities corresponding to the conditions of their original habitat, suggesting genetic adaptation to their environmental conditions and indicating that propagules transported from freshwater to brackish water or vice versa will hardly develop into fertile plants. Additionally, brackish water plants perform poorer in all aspects of sexual reproduction than freshwater plants. Possibly, successful dispersal of oospores is not subjected to high selective pressure within the Baltic Sea where new sites easily can be colonized by means of vegetative reproduction. We assume that these adaptations will favour speciation within C. aspera and support the idea of the geologically young Baltic Sea as a “cradle of plant evolution”. [Copyright &y& Elsevier]

Littoral diatoms were studied in two locations in the Shatt Al-Arab estuary, North West Arabian Gulf, a eutrophic brackish to marine environment whose diatom flora appears to be poorly known. A total of 170 taxa belonging to 70 genera were identified and documented by light microscopy. Large numbers of freshwater taxa washed down from the inland waters of South Iraq were observed. Cocconeis placentula and its variety euglypta, Cyclotella meneghiniana, Cymbella aspera, Gomphonema coronatum, G. truncawin, Pinnularia divergens and Surirella capronii were the most common freshwater taxa. The majority of the recorded taxa have a cosmopolitan geographic distribution, but some tropical and subtropical ones were also common: Cyclotella stylorum, Tryblioprychus cocconeiformis, Trachyneis debyi, Trachyneis anrillarurn, Trachyneis spp. and Gomphotheca sinensis. The taxon Navicula lyra var. abnormis Grunow in A. Schmidt is recombined in the genus Lyrella Karajeva and at the same time its taxonomic rank is raised to that of a species, Lyrella abnormis (Grunow in A . Schmidt) comb. et stat. nov. Navicula peculiaris Salah el Tamas is proposed as a taxonomic synonym of Lyrella abnormis. [ABSTRACT FROM AUTHOR]

Ecotypes of Fucus vesiculosus L. from the Norwegian Sea (34 psu, marine ecotype) and Bothnian Sea (5 psu, brackish ecotype) have been compared with respect to the ability to withstand desiccation at different temperatures (0, 10, and 20°C). The aim was also to investigate the importance of salinity and light for the availably energy reserves, osmotic adjustment, and pigment content. The maximum quantum yield of photosystem II photochemistry (Fv/Fm) values revealed that the marine ecotype was more able to resist desiccation. The brackish algae showed a decrease in Fv/Fm as a response to desiccation at all temperatures, but the decrease was most pronounced at 20°C. The brackish ecotype recovered from desiccation within 5 h only when treated at 0°C. When the two ecotypes were treated at different levels of salinity in darkness and light, the results suggested that both salinity and irradiance are main factors in the differences in mannitol content between the two ecotypes. Chlorophyll (Chl) measurements showed 25% higher Chl a and 60% higher Chl c in the brackish ecotype in comparison to the marine ecotype. Darkness had a more pronounced effect on the Chl content than the salinity and initiated an increase in the amount of Chl, especially Chl c in the brackish ecotype. [ABSTRACT FROM AUTHOR]

survey of oligohaline and mesohaline tidal marshes along the upper reaches of eight tidal rivers in the Great Bay Estuary of New Hampshire was conducted to document the occurrence of eastern grasswort, Lilaeopsis chinensis, a state-listed, rare species. Historical sites were visited to assess the presence, absence, or significant population changes of this rare coastal species. We re-located four of five historically documented element occurrences, noted the plant's potential expansion on several rivers and a decline at three other sites, and identified a new occurrence on a river system with no prior documented accounts. The results suggest that overall, L. chinensis has been relatively stable for the last 60 years, although the loss of plants at three of the sites suggests it is threatened by continued development (dams and tidal restrictions) and associated impacts to water quality. [ABSTRACT FROM AUTHOR]

Artificial sediment enhancement using a thin layer of dredged material has been suggested as a means to increase elevation and create soil conditions conducive to increased marsh structure and function in deteriorating marshes. Using a chronosequence approach, we examined the effects of sediment enhancement in deteriorating marsh and open-water pond habitats located in six brackish marshes. Sediment enhancement of both marsh and interior pond sites had significant, immediate, and long-lasting effects on physical soil properties and nutrient status with increased bulk density and inorganic nitrogen. Vegetative cover and productivity response were minimal for deteriorating vegetated marshes with the short- term response data showing no significant impact of sediment enhancement and long-term trends indicating decreasing productivity over time. In contrast, trajectory models of vegetative cover and productivity in interior pond sites showed increases over time indicating that, for restoration of interior ponds, sediment enhancement may prove valuable. The use of trajectory models emphasizes the need for long- term monitoring to determine restoration success of projects. [ABSTRACT FROM AUTHOR]

An undescribed species of tube-dwelling sigmoid diatoms, Gyrosigma orbitum sp. nov., was found in the surface sediments of a salt marsh in Peck's Cove, Bay of Fundy, Atlantic Canada. The specimens belong to the section Strigiles sensu H. Peragallo and they are characterized by very fine longitudinal striation (34–45 in 10 μm), isomorphic proximal raphe endings and two large oval pits within the central area. While recorded in adjacent tidal mudflats, this species reached its highest abundances in the salt marsh, particularly within the cordgrass Spartina patens where it occurred in association with other epipelic taxa, including Diploneis cf. smithii, Surirella spp., Gyrosigma limosum, Nitzschia epithemioides, N. ligowskii, N. sigma, and a number of small sigmoid Nitzschia species. Gyrosigma orbitum is found mainly at sites with high sediment temperature and water content, but a shallow anoxic layer. [ABSTRACT FROM AUTHOR]

Abstract: In this study, salt tolerance was investigated in Odyssea paucinervis Staph, an ecologically important C4 grass that is widely distributed in saline and arid areas of southern Africa. Plants were subjected to 0.2%, 10%, 20%, 40%, 60% and 80% sea water dilutions (or 0.076, 3.8, 7.6, 15.2, 22.8, and 30.4 parts per thousand) for 11 weeks. Increase in salinity from 0.2% to 20% sea water had no effect on total dry biomass accumulation, while further increase in salinity to 80% sea water significantly decreased biomass by over 50%. Morphological changes induced by salinity included reductions in the number of culms, leaves and internodes as well as decreases in internode length and leaf length:leaf width ratios. Carbon dioxide exchange, leaf conductance and transpiration decreased at salinities of 40% and higher, while quantum yield of photosystem II (PSII), electron transport rate (ETR) through PSII and intrinsic photosynthetic efficiency generally decreased at salinities of 60% and higher compared to 0.2% sea water. Concentrations of Na+ and Cl− increased significantly with salinity increase in both roots and shoots. Na+/K+ ratios in the roots and shoots ranged from 0.66 to 3.28 and increased with increase in substrate salinity. The maximal rate of secretion at 80% sea water was 415nmolcm−2 d−1 for Na+ and 763nmolm−2 d−1 for Cl− with high selectivity for these two ions. Predawn and midday ψ decreased with increase in salinity and were more negative than those of the treatment solutions. The concentration of proline increased with increase in salinity in both roots and shoots. The data clearly indicated that O. paucinervis is a highly salt-tolerant species that is morphologically and physiologically adapted to a saline environment. [Copyright &y& Elsevier]

Bacillaria paxillifera - perhaps better known by its synonym B. paradoxa - is epi-typified with material from close to the type locality. Its morphology - from the living cell and intact colony to the fine structure of the valve and girdle bands - is established using light microscopy, transmission electron microscopy and scanning electron microscopy. Since B. paxillifera is also the generitype, Bacillaria is here revised and emended to include only brackish-freshwater taxa showing the unique fibulate raphe system and construction type of this genus. Three new taxa are described within the re-defined genus: B. paxillifera var. czarneckii, B. kuseliae and B. urve-millerae, differing mainly in their raphe flanges, cell-outline and shape and number of plastids. The first taxon was found in both the Mississippi River, USA, and the River Weser, Germany, the second in the Avon River, Australia, and the third at a freshwater influx into the Atlantic in The Gambia, West Africa. Historical taxa, such as Grunow's B. paxillifera var. tumidula, var. tropica, and var. pacifica were also studied and lectotypified. [ABSTRACT FROM AUTHOR]

Former laboratory results indicate that shoot elongation at low light intensities of Chara aspera is absent already at 10 psu which is within the physiologically optimal salinity range for brackish water populations. To investigate if similar restrictions occur in the field, density and morphology of C. aspera were compared between three freshwater and three brackish water sites along its depth range. The lower depth limit of C. aspera varied considerably among sites (30–600 cm) related to turbidity. Light availability at the lower depth limit corresponded to about 15% of surface irradiance in freshwater and brackish water with lower salinity (3.4 psu). Total length increased and fresh weight:length ratio decreased with depth at these sites indicating shoot elongation related to lower light availability. Due to shoot elongation, light availability was far higher at the upper parts of the shoot than at the bottom in the turbid sites. Light availability at the lower depth limit was higher (about 40%) at two sites with higher salinity (7–8 psu), where no shoot elongation was observed at the lower depth limit. Instead, the plants were stunted and often covered with filamentous algae or shaded by other rooted submerged macrophytes indicating competitive disadvantages of C. aspera at higher salinities. As growth in high densities (mat formation) exposes the plants to severe self-shading, it is suggested that shoot elongation is a prerequisite to mat formation. Dense vegetation of C. aspera was found only in freshwater and brackish water with lower salinity. Single, richly branched plants occurred in clearwater sites with higher salinity. C. aspera was not found in “double stress” environments with both high turbidity and high salinity: We asume that the species is a poor competitor under these conditions. Our results indicate that morphological differences between freshwater and brackish water populations of C. aspera are at least partly explained by salinity rather than genetic differences. [ABSTRACT FROM AUTHOR]

Kochia sieversiana (Pall.) C. A. M., a naturally alkali-resistant halophyte, was chosen as the test organism for our research. The seedlings of K. sieversiana were treated with varying (0–400 mM) salt stress (1:1 molar ratio of NaCl to Na2SO4) and alkali stress (1:1 molar ratio of NaHCO3 to Na2CO3). The concentrations of various solutes in fresh shoots, including Na+, K+, Ca2+, Mg2+, Cl−, SO, NO, H2PO, betaine, proline, soluble sugar (SS), and organic acid (OA), were determined. The water content (WC) of the shoots was calculated and the OA components were analyzed. Finally, the osmotic adjustment and ion balance traits in the shoots of K. sieversiana were explored. The results showed that the WC of K. sieversiana remained higher than 6 [g g−1 Dry weight (DW)] even under the highest salt or alkali stress. At salinity levels >240 mM, proline concentrations increased dramatically, with rising salinity. We proposed that this was not a simple response to osmotic stress. The concentrations of Na+ and K+ all increased with increasing salinity, which implies that there was no competitive inhibition for absorption of either in K. sieversiana. Based on our results, the osmotic adjustment feature of salt stress was similar to that of alkali stress in the shoots of K. sieversiana. The shared essential features were that the shoots maintained a state of high WC, OA, Na+, K+ and other inorganic ions, accumulated largely in the vacuoles, and betaine, accumulated in cytoplasm. On the other hand, the ionic balance mechanisms under both stresses were different. Under salt stress, K. sieversiana accumulated OA and inorganic ions to maintain the intracellular ionic equilibrium, with close to equal contributions of OA and inorganic ions to anion. However, under alkali stress, OA was the dominant factor in maintaining ionic equilibrium. The contribution of OA to anion was as high as 84.2%, and the contribution of inorganic anions to anion was only 15.8%. We found that the physiological responses of K. sieversiana to salt and alkali stresses were unique, and that mechanisms existed in it that were different from other naturally alkali-resistant gramineous plants, such as Aneurolepidium chinense, Puccinellia tenuiflora. [ABSTRACT FROM AUTHOR]

Oritani Marsh in the Hackensack Meadowlands of urbanized northeastern New Jersey USA was assessed in 2000 for vegetation, soil/sediment chemistry, abundance/diversity of benthic invertebrates, and bird and mammal usage. Vegetatively, both marsh and uplands are dominated by tall, dense Phragmites australis. Small patches (less than 2 hectares total) dominated by Spartina spp. were found at the lowest elevations. Soil/sediment cores were sliced into 5 intervals and analyzed for metals, pesticides and volatile/semivolatile organic compounds. Thirteen locations had at least one chemical above Long et al.’s [ Environmental Management, 19, 1995, 81--97] “Effects Range-Median” (ERM). Seven metals and nine organics exceeded ERM in at least one sample, with mercury showing the most exceedances. The surface 15 cm interval was generally more contaminated with metals than the 15 to 30 cm interval; the reverse was true for semivolatile organic compounds. Twenty taxa of benthic macroinvertebrates were collected, with each location producing from 1 to 9 taxa. Abundance ranged from 11 to 3,889 individuals/m2. Number of taxa was moderately ( r 2 between 0.40 and 0.70) negatively correlated with zinc, beryllium, nickel and arsenic concentrations; no other chemical’s r 2 was above 0.25. Diversity was moderately negatively correlated with arsenic and beryllium. These correlations were unexpected: zinc, beryllium, nickel and arsenic were not the chemicals found at the highest concentrations relative to benchmarks. Number of taxa, abundance and diversity were moderately (negatively) correlated with elevation; organic carbon was moderately (positively) correlated with abundance. All other correlations were weak ( r 2 < 0.35). Live traps captured only one mammal species, the meadow jumping mouse. Bird observations revealed 39 species, dominated by a few common species. [ABSTRACT FROM AUTHOR]

As part of the development of rapid assays to measure ecological processes, rates of decomposition of eelgrass, Zostera capricornii, were measured using litter bags placed at different distances from the sea in a coastal lake system. Average loss of dry mass over 28 d in bags with coarse mesh, which excluded animals > 1.5 mm, varied from 364 to 448 mg in late winter to between 644 and 868 mg in autumn, depending on locality. Rates of loss were significantly greater in bags with small mesh (0.063 nun), from which all macrofauna were excluded, varying from 420 to 532 mg and from 868 to 924 mg in winter and autumn, respectively. There were consistent negative correlations between loss of litter and numbers of macrofauna and meiofauna in the bags. Rates of decrease in the organic fraction of the litter were positively correlated with numbers of animals. The results imply that the fauna inhibited decomposition, possibly by reducing microbial populations through grazing. [ABSTRACT FROM AUTHOR]

Abstract: Cynara cardunculus L. is a robust thistle widespread in arid and semi-arid regions where high salinity is frequently present, but information about salt stress tolerance in this plant is almost null. This study examines the effect of salts (NaCl and KCl) on the growth, ion and other solutes accumulation and distribution through the plant. Moreover, Na+ and Rb+ (K+) uptake and translocation in the presence of specific water stress were determined. Moderately high concentrations of salt decreased the weight of the plant. However, a differential effect between NaCl and KCl was found. High concentrations of K+ produced higher deleterious effects than the same amounts of Na+. KCl was more toxic for the plant, probably because of the high accumulation of K+ ions in the plant. Osmotic adjustment was mainly due to inorganic ions and not to other organic solutes. Water stress promoted Na+ but not Rb+ (K+) uptake and translocation to the shoot. It is proposed that strategies present in halophytic plants to cope with high salt can be found in C. cardunculus although this plant cannot be considered as a typical halophyte. [Copyright &y& Elsevier]

Ecologists have long speculated that species with wider environmental ranges would have broader ranges in phenotype; however, most tests of this hypothesis have involved small numbers of species and/or closely related taxa. We related phenotypic variation in twelve salt marsh plant species from six families to variation in four environmental variables using multiple regression. Within species, plant phenotype was predictably related to environmental variation. Salinity was the most common predictor of plant traits, followed by organic content, water content and elevation. Across species, regressions of single plant trait CVs on range (2 × SD) of single environmental variables were not significant and did not support the hypothesis that species occupying broad environmental ranges would have broad ranges in phenotypes. However, regression of a composite phenotypic PCA1 on a composite environmental PCA1 showed a marginally significant ( P = 0.054). linear relationship for 10 species. Considering the different patterns of response across species, the lack of a relationship between variation in single phenotypic traits and single environmental variables is likely because the distantly-related taxa employed fundamentally different morphological and physiological strategies to respond to environmental stress gradients. The significant relationship between composite environmental and phenotypic variables reflects the complex nature of species phenotypic response to multivariate environmental gradients. Specifically, in this system, species increase variation in the number of leaves, but decrease variation in leaf size in response to an increase in range of salinity and decrease in range of water and organic content. [ABSTRACT FROM AUTHOR]

The effects of salinity on growth, maturation and photosynthesis were examined in the filamentous algaRhizocloniumsp. (Cladophoraceae, Chlorophyta) growing in a brackish water habitat in a canal draining into Tokyo Bay, Japan. In this habitatRhizocloniumsp. was exposed to a wide salinity range, both daily, 5−23‰ during November 1996, and hourly, 6−24‰ during the spring tide day. From the results of culture experiments, growth and maturation ofRhizocloniumsp. occurred in the wide salinity range of 10−40‰ at 20 µmol photons m−2s−1 at 20°C, but did not occur at salinity of 0‰. Light saturation on the photosynthesis-irradiance curve at 20°C at 20‰ was reached at 100 µmol photons m−2s−1, which is characteristic for shade-adapted algae. On the photosynthesis-salinity curve at 20°C at saturated irradiance (160 µmol photons m−2s−1), the net photosynthetic rate increased with increasing salinity up to 30‰ but decreased at 40‰. On the photosynthesis-salinity curve at 20°C at 20 µmol photons m−2s−1 (at nearin situirradiance), the photosynthetic rates were almost the same in the salinity range from 0 to 40‰. Therefore, this species is able to grow, reproduce and photosynthesize with a relative efficiency in a wide salinity range, which shows that it is well adapted to a brackish water environment. [ABSTRACT FROM AUTHOR]

Horizontal-tube falling film condensers are used in many fields: chemical industries, refrigeration, desalination, cooling, etc. However, their performances cannot be predicted precisely due to the complexity of the phenomena. In this paper, heat and mass transfer in a horizontal-tube falling-film condenser used in an innovative desalination plant was studied theoretically. The polypropylene exchanger was designed to work at relatively high temperatures (25–35°C). In fact, the desalination unit was designed to function in remote areas where the ambient temperature frequently exceeds 30°C [1]. The model developed uses basic aerodynamic, hydrodynamic and heat/mass transfer information to predict the performance of the exchanger. The predicted transfer characteristics obtained from the simulations were compared to experimental data [2]. From this comparison, it was seen that the model is well able to predict the trends of heat and mass characteristics of the condenser. The influence of the different thermal, hydrodynamic and geometric parameters on the condenser performances was investigated. The variations of the distilled water amount inside the exchanger were analysed. The results were used to determine the optimum operational conditions. Finally, the model was also used to optimise the different exchanger components. [Copyright &y& Elsevier]

In this paper, we compare the classification effectiveness of two relatively new techniques on data consisting of leaf-level reflectance from five species of salt marsh and two species of crop plants (in four experiments) that have been exposed to varying levels of different heavy metal or petroleum toxicity, with a control treatment for each experiment. If these methodologies work well on leaf-level data, then there is hope that they will also work well on data from air- and spaceborne platforms. The classification methods compared were support vector classification (SVC) of exposed and nonexposed plants based on the spectral reflectance data, and partial least squares compression of the spectral reflectance data followed by classification using logistic discrimination (PLSILD). The statistic we used to compare the effectiveness of the methodologies was the leave-one-out cross-validation estimate of the prediction error. Our results suggest that both techniques perform reasonably well, but that SVC was superior to PLS/LD for use on hyperspectral data and it is worth exploring as a technique for classifying heavy-metal or petroleum exposed plants for the more complicated data from air- and spaceborne sensors. [ABSTRACT FROM AUTHOR]

A comparison of the vegetation of two pans (playas) inside Soetdoring Nature Reserve, a freshwater and a brackish pan, is presented. These ephemeral pan communities are also compared to the vegetation of the hot spring and two permanently inundated earth dams inside the brackish pan's basin. The vegetation of the freshwater communities differs significantly from that of the brackish pan itself. The freshwater pan was classified as a Mixed Grass Pan and the brackish pan as an Open Diplachne Pan. The Mixed Grass Pan is characterised by a Cynodon transvaalensis-Gnaphalium declinatum community, associated with the following subcommunities: Selago dinteri-Cynodon transvaalensis, Panicum schinzii-Cynodon transvaalensis and Portulaca oleracea-Cynodon dactylon subcommunity. Cynodon transvaalensis is the dominant species in this pan. The Open Diplachne Pan is characterised by a Diplachne fusca-Eragrostis bicolor community with a Diplachne fusca subcommunity and an Eragrostis bicolor-Diplachne fusca subcommunity associated with it. Diplachne fusca is dominant in the pan basin. A TWINSPAN classification, refined by Braun-Blanquet procedures, revealed five distinct plant communities for the pan basins and freshwater areas inside the basin collectively. This information is important since very few published analyses are available for pans in the Free State Province, as well as in South Africa as a whole. [ABSTRACT FROM AUTHOR]

From the ice plant, Mesembryanthemum crystallinum, McHKT1 was isolated encoding a protein 41–61% identical to other plant HKT1-like sequences previously described as potassium or sodium/potassium transporters. McHKT1 acts as a potassium transporter in yeast with specificity similar to that of wheat HKT1. In Xenopus oocytes it transports cations with a specificity Rb+ > Cs+ > [K+ = Na+ = Li+]. McHKT1 is exclusively localized to the plasma membrane. The isoform isolated is most highly expressed in leaves and is present in stems, flowers and seed pods but absent from the root where, according to immunological data, a second isoform exists which does not cross-hybridize with the leaf form in RNA blots at high stringency. McHKT1 transcript amounts increase during the first 6–10 h of stress and then decline to pre-stress levels with kinetics reminiscent of the initial influx of sodium into this halophyte. Immunocytological localization showed strong signals in the leaf vasculature and surrounding mesophyll cells but low-intensity signals are also detected in other cell types. In roots, McHKT is mainly confined to endodermis and stele. Possible functions of McHKT1 in ion homeostasis in the halophytic ice plant are discussed. [ABSTRACT FROM AUTHOR]

Sub-fossils of Cladocera and Foraminifera were used to reconstruct changes since 1870 in the trophic dynamics of two brackish lakes, Glombak and Han Vejle, located in the Vejlerne nature reserve, Denmark, a site of international conservation importance. After creation of the lakes in the mid-1870s following land reclamation, the two lakes have developed quite differently; today Glombak is turbid, while Han Vejle is clear. In both lakes, stratigraphic changes in the assemblages of foraminifers and cladocerans indicate an abrupt shift from marine to brackish conditions at the end of the 19th century, coinciding with land reclamation. However, the composition of the fossil invertebrate assemblages in the 20th century implies differences in the exposure to salinity, in fish predation and in habitat diversity. In Glombak, the cladoceran record suggests relatively saline conditions in the first quarter of the last century and high macrophyte abundance followed by lower salinities and subsequently a major decrease in macrophyte abundance and an increase in fish predation during the past ca. 40 years. By contrast, in Han Vejle low salinity, high abundance of macrophytes and only minor changes in fish predation seem to have prevailed throughout most of the 20th century. The results are consistent with recent contemporary data, the few historical records, as well as with trends in the records of diatoms and macrofossils. This study highlights the potential of using crustacean remains as indicators of long-term changes in the trophic dynamics of brackish lakes. [ABSTRACT FROM AUTHOR]

Because of the potentially detrimental effects of seed production on adult survivorship and growth, moderate flower harvesting may have little negative impact on population growth of long-lived perennial plants such as Limonium carolinianum (Walter) Britton. We examined this by collecting data on survivorship, growth, and fecundity of an unharvested population over a period of 5 years and conducted a controlled experiment to examine the effect of harvesting on adult survivorship and growth over a 3-year period. Data were summarized in the form of a stage-structured matrix population model with a stochastic element that incorporated year-to-year variation in transition probabilities. Contrary to our original hypothesis, we found that preventing seed set through removal of flowers did not increase adult survivorship or growth. By determining the harvest level that reduced population growth rate to 1.0, we estimated the maximum sustainable harvest level to be 16%, a value that is approximately half that of reported harvest levels on accessible marshes in the study area. In spite of this, the reported harvest levels are unlikely to drive local populations to extinction in the foreseeable future. Providing the adult population size is >100 and harvest levels are <90%, time to local extinction will exceed 100 years. This is a function of the very high survivorship of adults in this species and the fact that harvesting has no negative impact on adult survivorship or growth. However, because of the long preadult phase in this species (8–9 years) and the fact that fecundity of young adults is low, recovery from overharvesting is extremely slow. Adult population size can be reduced to 25% of its original value in 7 years at high harvest levels, but it will take 34 years on average to recover once harvesting is terminated.Key words: cost of reproduction, stage–structures matrix population model, sustainable harvest, conservation of biodiversity.Considérant les effets négatifs potentiels de la production de semences sur la survie et la croissance des plantes adultes, une récolte modérée des fleurs pourrait n'avoir que de faibles effets négatifs sur la croissance des populations de plantes pérennes longivives telles que le Limonium carolinianum. Les auteurs ont examiné cette hypothèse en récoltant des données sur la survie, la croissance et la fécondité d'une population non-récoltée au cours de cinq années, et ont conduit une récolte expérimentale pour en examiner l'effet sur la survie et la croissance des plantes adultes, au cours d'une période de trois ans. Ils ont résumé les résultats sous forme d'un modèle de population matriciel structuré par étapes, incluant un élément stochastique qui incorpore la variation d'année en année dans les probabilités de transition. Contrairement à l'hypothèse originale, les auteurs ont constaté que l'absence de mise à fruit par ablation des fleurs n'augmente ni la survie, ni la croissance des plantes adultes. En déterminant le niveau de récolte qui réduit le taux de croissance de la population à 1.0, les auteurs estiment que le taux de récolte maximale durable est de 16 %, soit une valeur qui est environ la moitié des taux de récolte rapportés pour les marais accessibles de la région étudiée. En dépit de cette situation, il est peu probable que les taux de récolte signalés conduisent à l'extinction des populations dans un avenir prévisible. Pourvue que la dimension de la population soit >100 et que les taux de récolte soient <90 %, le temps nécessaire à l'extinction dépasse 100 ans. Ceci tient compte du taux très élevé de survie des adultes chez cette espèce et du fait que la récolte est sans effet sur la survie ou la croissance des adultes. Cependant, à cause de la longue phase pré-adulte chez cette espèce (8–9 ans), et du fait que la fécondité des jeunes adultes est faible, le rétablissement après la récolte est extrêmement faible. Sous une récolte intensive, la dimension d'une population peut être réduite à 25 % de sa valeur originale en 7 ans, mais il faudra en moyenne 34 ans de récupération, une fois la récolte arrêtée.Mots clés : coût de la reproduction, modèle de population par matrice d'étapes structurales, récolte durable, conservation de la biodiversité.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

In this review I will describe the importance of seed banks and the population dynamics of seeds on the distribution of species in saline habitats. The main questions being examined in this review include: 1. Does the seed bank represent the flora of the entire salinity gradient or is it restricted to the species in each zonal community? 2. Is the size and species composition of the persistent seed bank regulated by the degree of salt stress in habitats along an environmental gradient? 3. Does the population dynamics of seeds influence the temporal and spatial distribution of plant species in saline habitats? Seed banks may be transient or persistent depending upon the physiological responses of species and the soil environment in which the seeds are found. The formation of zonal communities in salt marsh environments is affected by changes in soil salinity and flooding along an elevational gradient. Population dynamics of seeds have been found to determine the spatial and temporal distribution of species along salinity gradients. The flora and relative density of species of zonal communities are significantly dependent upon the stress tolerance of species at different stages of development and the presence of transient or persistent seed banks. The occurrence of a seed bank is related to the salinity tolerance of species at the germination stage of development, a seeds ability to tolerate hypersaline conditions and flooding, and whether or not species are able to maintain a persistent seed bank until hypersaline conditions are alleviated. [ABSTRACT FROM AUTHOR]

We have investigated conditions leading to the degradation of glycinebetaine in Aphanothece halophytica and have shown the activity of betaine-homocysteine methyltransferase (BHMT). The intracellular glycinebetaine level was decreased approximately 50% after 36 h salt downshock from 2.0 m NaCl medium to 0.5 m NaCl medium. A slight additional decrease of glycinebetaine occurred when salt downshock was combined with dark treatment. The omission of carbon and nitrogen sources in the growth medium further decreased intracellular glycinebetaine. The activity of BHMT increased from 0 to 460 nmol h-1mg-1 after 3 h salt downshock. Higher strength of salt downshock resulted in higher activity of the enzyme. Small increase of the enzyme activity was also observed when A. halophytica was deprived of carbon and nitrogen sources in the growth medium. [ABSTRACT FROM AUTHOR]

The effect of Mg2+, Na+, K+ ouabain and pH on ATPase activity of purified membrane fractions enriched in plasmalemma fragments from Hordeum vulgare L. (glycophyte) and Halocnemum strobilaceum L. (halophyte) was studied. Membrane ATPases from both plants were synergistically activated by K+ and Na+ in the presence of Mg2+. The maximum activity of the enzymes were observed at the ratio Na/K = 2-3. Ouabain (10-4 M) almost completely eliminated the (Na+ + K+)-stimulated component of the ATPase activity. The Na, K, Mg-ATPase of Hordeum had a single pH optimum (pH 8), but that of the Halocnemum had two optima(pH 6 and 8). It appears that similar enzymes operate in the cells of both plants studied. The higher Na, K, Mg-ATPase activity of the halophyte compared to that of the glycophyte suggests the involvement of the enzyme in the extrusion of Na+ from the cytoplasm of cells of both plants. [ABSTRACT FROM AUTHOR]

The occurrence of glutamine synthetase, glutamate synthase and glutamate dehydrogenase in a range of halophytic higher plants has been investigated. Ferredoxin-dependent glutamate synthase was found in shoot tissue of all the species examined. Root tissue glutamate synthase was active with both reduced pyridine nucleotides and reduced ferredoxin. The levels of enzymes present in the majority of species are consistent with the view that ammonia assimilation occurs via the combined action of glutamine synthetase and glutamate synthase. An increase in external salinity lowers the levels of glutamine synthetase and glutamate dehydrogenase of root tissue but increases the level of shoot glutamine synthetase. [ABSTRACT FROM AUTHOR]

Pyruvate kinase enzymes were partially purified from leaves of halophytes, Atriplex gmelini C. A. Mey., Chenopodium acuminatum Wild, and Spergularia salina J. et C. Presl., grown hydroponically in the presence of 250 mM NaCl in a greenhouse, to determine their Km values for potassium. The values were all ca 10−3M, as also reported for the glycophyte enzymes. However, the Km values were reduced by 60 to 70% by the addition of betaine to a concentration of 1 M. [ABSTRACT FROM AUTHOR]

The present paper reports a study into the activity of nitrate reductase in plants of Suaeda maritima. The growth of S. maritima in the upper salt-marsh appears nitrogen limited, going from the upper to lower marsh there is a three-fold increase in total nitrogen of the plants. Nitrogen status and the activity of nitrate reductase are related. Plants from the lower marsh contain a fifty times higher level of enzyme than those from the upper marsh. By feeding nitrate to plants at different sites in the marsh it was possible to induce high nitrate reductase activity in plants that previously contained low levels of the enzyme. At all sites there is an equal potential to induce nitrate reductase. The induction experiments with plants in situ suggest that in this marsh nitrate availability is the main factor limiting the growth of S. maritima in the upper marsh. [ABSTRACT FROM AUTHOR]

The article offers information about Aster Tripolium, a plant found in the British Isles. Its stem measures from one to two feet, is erect, glabrous, leafy, and branched. Aster Tripolium is a common salt-marsh plant of the seashore, occurring also on cliffs and rocks near the sea, and in inland saline areas. It generally thrives in salt marshes with frequent tidal inundations, and confined naturally to saline habitats, but can be grown in non-saline soils and shows optimal development in slightly brackish conditions.