High Salinity Areas Research Articles

A study on the effects of salinity and pH on PSII function in mulberry seedling leaves under saline–alkali mixed stress

To clarify the photosynthetic physiological response of mulberry seedlings under mixed saline–alkali stress, different saline–alkali combinations were prepared to study its effect on leaf water content, chlorophyll content, and changes of chlorophyll fluorescence parameters of mulberry seedlings leaves. Different saline–alkali combinations were composed of three salt concentrations (50, 100, and 200 mmol L−1) and four pH gradients (7.0, 8.0, 9.0, and 10.0) in different proportions, of which salt concentrations were prepared with two neutral salts (NaCl and Na2SO4) and two alkaline salts (Na2CO3 and NaHCO3) in different proportions. The results showed that different pH levels had relatively limited influence on chlorophyll fluorescence parameters of mulberry seedling leaves when the salt concentration was 50 mmol L−1 and 100 mmol L−1, but the photochemical activity decreased slightly with the increase of the pH value in the 100 mmol L−1 treatment. When salt concentrations increased to 200 mmol L−1, the photochemical efficiency of PSII in mulberry seedling leaves decreased significantly. With the increase of the pH value, the reduction of the PSII reaction center activity in mulberry seedling leaves was accelerated. Mixed saline–alkali stress also resulted in a significant decline in the electron transport rate (ETR) of mulberry seedling leaves, which was mainly due to the decrease in activity of the oxygen-evolving complex (OEC) on the PSII donor side and the blockage of electron transfer from QA to QB on the PSII acceptor side. This electron transfer on the PSII acceptor side was the main target point of saline–alkali stress. At a salt concentration of 100 mmol L−1, mulberry seedlings dissipated excess light energy by increasing non-photochemical quenching (NPQ). However, at the 200 mmol L−1 salt concentration, the protective ability of NPQ decreased, and the reduction was more significant at a high pH value, which led to the accumulation of excess excitation energy (1 − qP)/NPQ and the aggravation of photoinhibition. Saline–alkali mixed stress also significantly changed the energy distribution parameters of the PSII reaction center. A higher salt concentration and pH value led to inactivation or degradation of the PSII reaction center and reduced the ability of antenna pigment to capture light energy. Under the interaction of high salt concentration and high pH value, mulberry seedlings dissipated excess excitation energy mainly in the form of heat energy with the decrease of NPQ. In conclusion, the effects of salt and pH value on the PSII function in mulberry seedlings leaves were minimal under low salt concentrations, and there was no significant interaction between them. However, salt and pH showed significant interactions under the high salt concentration, and the higher pH value affected photoinhibition in PSII under saline–alkali stress. Therefore, the influence of total alkalinity and alkalinity should be considered when planting mulberry in high salinity areas.

English

Avocado (Persia americana) a very important crop worldwide nutritionally and economically. In Kenya avocado does not thrive well in soils with high salinity, flooded or waterlogged areas. Survey was conducted around Lake Victoria Basin in Kenya to establish socioeconomic factors and flooding that affects its production. A sample of 400 households was interviewed using structured questionnaire, focus group discussions and key informants. Data were collected and analysed using Statistical Package for Social Scientists. Objectives were to find how flood, human capital and other socioeconomic factors such as gender, age, farmer education affects avocado production in areas with saline soils and floods among other factors namely Busia, Muhoroni, Nyando and Rachuonyo counties in Kenya. Results indicated that the major impediments were water logging (76.2%), flooding (73.0%), soil fertility (62.5%) and soil salinity (42.9%), to agricultural development and affect the crop production. Farmers had limited access to information on avocado production and marketing 31.3%, and sourced information from fellow farmers. Majority of farmers owned indigenous or non-certified avocado trees; low fruits market prices also discouraged its production. Therefore, farmers should be sensitized on the impacts of climate change on agriculture, encourage majority of them to take samples of their plots for soil analysis. 65.5% expressed soil fertility problems in their farms yet 95.5% of them had not taken their plots for soil analysis. Increasing of human capital, farmer education, and extension services may contribute to farmer’s abilities to adopt new technologies for increased avocado production in these areas and may positively contribute to improved livelihood through nutrition, income generation of the stakeholders. Farmers should be encouraged to plant certified avocado seedlings tolerant to water logging and salinity. Key words: Avocado, climate change, Lake Victoria, Kenya, strategies.

COMPOSITION AND DISTRIBUTION OF FISH LARVAE SURROUNDING THE UPWELLING ZONE IN THE WATERS OF NORTHEASTERN TAIWAN IN SUMMER

We investigated the species composition and distribution of fish larvae surrounding the upwelling zone in the waters of northeastern Taiwan in July 2011. The surface water had higher temperatures (25.7°C-28.3°C) and lower salinity (33.67-34.05 psu) than did lower water columns. A divergent trend was observed between temperature and salinity in the waters above 80 m. Moreover, we identified a cold-core eddy at the upwelling of the Kuroshio subsurface at waters approximately 60 m beneath the surface. In total, 1834 fish larvae were collected from eight stations; 85 taxa contributing to 60 families were identified. The abundance of fish larvae varied among stations. The five predominant larval taxa, which constituted 50% of the total fish larvae, were Auxis spp. (30.14%), Sciaenidae spp. (6.73%), Decapterus spp. (6.29%), Champsodon spp. (5.52%), and Gobiidae spp. (4.83%). Higher diversity and lower evenness index values were recorded in areas of high temperature and low salinity. Two larval fish assemblages, Mixed Coastal Group and Upwelling Group, were identified from a cluster analysis. Mixed Coastal Group exhibited higher density, higher temperature, and lower salinity than Upwelling Group did. Thus, in general, the density, spatial distribution, composition, and diversity of fish larvae differed, and the salinity at the 20-m layer exerted a more substantial effect on larval distribution in this study.

Adaptation of mangrove trees to different salinity areas in the Ayeyarwaddy Delta Coastal Zone, Myanmar

Mangroves in the Ayeyarwaddy Coastal Delta Zone (ADCZ) of Myanmar are well known for their rich biodiversity and their enormous ecosystem services. However, as recently evident from the adverse impacts of Cyclone Nargis in 2008, they are increasingly threatened by the impacts of climate change and variability. This study was aimed to understand mangrove species composition and their characteristics driven by climate-related variables such as salinity. Transect survey method to investigate the species composition and mangrove quality including tree density, canopy height, and diameter at breast height and species distribution were used. The study was conducted during 2015–2017 in Laputta and Bogalay Townships of ADCZ. Individual transects of 500 m which included six sample plots of 15 m × 15 m along each transect line were investigated. Salinity was significantly higher in Laputta (14.4 ± 3.0 PSU in November - 28.8 ± 0.5 PSU in May) than in Bogalay (0.5 ± 0.2 PSU in November - 14.4 ± 3.0 PSU in May). Six species were confirmed to grown only in the high salinity area at Laputta. Nine species showed a preference for low salinity area at Bogalay. Among the thirty species, fifteen species were documented as the highest salt tolerant species as observed in both low and high salinity areas.

Synechococcus bloom in the Pearl River Estuary and adjacent coastal area-With special focus on flooding during wet seasons.

Based on the field surveys aimed at understanding the variations of Synechococcus (Syn) abundance in the Pearl River Estuary during different seasons. We found that heavy terrestrial precipitation result in significant riverine runoffs and promote Syn growth, extension and blooms during warm and wet seasons. To understand the ecological role of Syn play in this estuary during wet seasons, we combined flow cytometry and high throughput sequencing (HTS) of 16S rDNA to investigate the phytoplankton distribution patterns and the potential shaping mechanisms during a typical wet season. During the cruise, picophytoplankton, especially Syn, and Nano-eukaryotes contributed importantly to the total phytoplankton biomass of the estuary. Syn can be further divided into phycoerythrin (PE)-rich Syn and phycocyanin (PC)-rich Syn, with PC-rich Syn about 1.5 times higher than PE-rich Syn in abundance. Both PE-rich Syn (60.75 × 103 cells ml-1) and PC-rich Syn (604.05 × 103 cells ml-1) reach the highest abundance at the lower part of the estuary. Moreover, PE-rich Syn can be divided into two subgroups which showed different salinity preference, with PE1 distributed in the high salinity area (with salinity >25) while PE2 in the middle salinity area (with salinity 7-20). Our results from the 16S rDNA sequencing also indicated abundant diversity and different niche adaptation of Syn with the operational taxonomic units (OTUs) along the estuary. Besides, analysis also indicated a tight correlation between estuarine Syn and active heterotrophic bacteria, especially groups of Rhodobacteria and Actionobacteria.

Soil salinity mapping in Everglades National Park using remote sensing techniques and vegetation salt tolerance

Everglades National Park (ENP) is a hydro-ecologically enriched wetland with varying salinity contents, which is a concern for terrestrial ecosystem balance and its nearby urban sustainability. In this study, spatio-temporal soil salinity maps are created using remote sensing techniques, coupled with literature review to understand vegetation salt tolerance properties, and field assessments entailing insitu electric conductivity (EC) measurements. The mapping first entailed the execution of a supervised machine learning technique—the maximum likelihood classification algorithm—to delineate seven vegetation-based land cover classes for the area, namely, mangrove forest, mangrove scrub, low-density forest, sawgrass, prairies and marshes, barren lands with woodland hammock and water, for the years 1996, 2000, 2006, 2010 and 2015. The classifications for 1996–2010 yielded accuracies of 82%–94%, and the 2015 classification was supported through ground truthing. Afterwards, EC tolerance thresholds for each vegetation class were established, which yielded soil salinity maps comprising four soil salinity classes—i.e., the non- (EC = 0–2 dS/m), low- (EC = 2–4 dS/m) and high-saline (EC ≥4 dS/m) areas. The soil salinity maps visualized the spatial distribution of soil salinity with no significant temporal changes. Furthermore, insitu EC measurements carried out at 23 sampling sites covering all land cover classes mostly validated (91% samples were tested within range) the estimated soil salinity ranges for the latest distribution. The approach of using land cover classes to sense salinity ranges in an urban-proximal ecosystem is pragmatic and application oriented, attributing to novel and useful study upshots considering the diversifying ecological context.

Origin and hydrogeological setting of saline groundwater discharges to the Athabasca River: Geochemical and isotopic characterization of the hyporheic zone

Identifying impacts of oil sands development on aquatic ecosystems requires understanding of the natural background water quality. In the Athabasca Oil Sands Region of Alberta this is challenging because the Athabasca River is incised directly into bitumen saturated sands of the McMurray Formation, and other saline Cretaceous and Devonian formations. This study compares the geochemical and isotopic composition of porewater sampled from the alluvial sediment beneath the Athabasca River with regional groundwater data to identify the geological origin of these saline groundwaters, and improve characterization of natural background sources of solutes entering the Athabasca River. Terrain conductivity surveys conducted along the Athabasca River were used to identify areas with evidence of saline groundwater discharge. Porewater samples were obtained from the alluvial sediment using drive point piezometers installed between 1 and 3 m below the water-sediment interface and were analyzed for δ18O, δ2H, δ34SSO4, δ18OSO4, 87Sr/86Sr, δ13C-DIC, δ13C-DOC, 3H, and 14C. The porewater in the alluvial sediment showed variable degrees of mixing with the overlying Athabasca River water, but the geochemical and isotopic composition in zones 1, 3 and 5 are consistent with discharge of saline groundwater from Cretaceous or Devonian units. The low percentages of modern carbon, and δ18O, δ2H, δ34SSO4, δ18OSO4, and 87Sr/86Sr signatures in the deepest porewater samples from Zones 1, 3 and 5 indicate glaciogenic water with high total dissolved solids originating from Devonian sourced solutes. Theses saline groundwater discharge zones occur where higher horizontal hydraulic gradients coincide with areas of higher salinity in the adjacent Cretaceous and Devonian aquifers, and areas with vertical connectivity with underlying Devonian aquifers. The results of this study demonstrate the influence of groundwater-surface water interactions and saline bedrock formation water discharge to water quality along some reaches of the Athabasca River which need to be considered in monitoring and water management strategies.

English

Soil salinization is one of the major constraints in achieving food security and environmental degradation in Ethiopia. Restoration of salt-affected lands into productive lands and protection of newly developed areas from the spread of salinity is therefore of paramount importance. In high salinity areas where technical solutions to soil rehabilitation are expensive and time consuming and growth of normal field crops is restricted, use of bioremediation methods including planting halophytic forages could bring these soils back into production. This paper identifies different causes of salinity and characterizes soils based on severity of salinity levels. The paper suggests that biosaline agriculture is an economical and effective approach to use unproductive lands for growing different food and fodder crops in Ethiopia. This approach, if prudently adapted, can help in improving livelihood of rural and pastoral communities of the salt-affected areas by enhancing feed and fodder production. The paper has recommended many unexplored and unexploited genetic variation that can be harnessed to improve the salt tolerance of field crop species. Productivity of marginal lands can be maximized for field crops and fodder species and varieties that can tolerate soil salinization and poor irrigation water quality. Key words: Soil salinity, halophytes, biosaline agriculture, food security, salt-tolerance, marginal lands.

Statistical analysis of the hydro-geochemical evolution of groundwater in the aquifers of the Yarmouk basin, North Jordan

The aim of this study is to determine the main factors affecting the quality of groundwater and its changes through hydro-geochemical analysis and statistical studies. Therefore, hydro-geochemical properties of groundwater are analyzed as Ca2+, Mg2+, Na+, K+, HCO3−, Cl−, NO3−, SO42−, and F− as well as their statistical data. Correlation, cluster, and factor analyses were applied on 1322 groundwater samples collected from 148 wells distributed through Yarmouk basin region, North Jordan. Clusters analysis shows two groups of ionic concentrations. Cluster 1 includes 37% of the total samples and classified as brackish and unsuitable water, while 63% follows cluster 2 and is classified as moderately soft and suitable water. Factor analysis tends to increase concentration and spread of Ca2+, Mg2+, Na+, K+, Cl−, and SO42− in the groundwater through factor 1 which reflects the high salinity as a result of over-pumping, weathering processes, and salts leaching from the top soil. Cluster 2 shows high concentrations of NO3− in groundwater as a result of the pollution due to agricultural and industrial human activities. Factor scores suggest the main hydro-geochemical zones in the study area, which are distributed in the northern, eastern, and south-eastern parts, which recorded an increase of Cl− (high salinity areas). The western region appears to increase in nitrate and chlorine concentrations (high level of salinity), while hardness factor spreads across the northern and southern parts of the study area.

Microfossils in surface sediments of brackish waters on the west coast of South Africa and their palaeoecological implications

A faunistic survey covering 25 sites in estuaries, coastal lakes and ponds along the west coast of South Africa between the Cape of Good Hope in the south and the Olifants River in the north was carried out in May 2014. The study aimed to establish a dataset with ecological and distribution data of ostracods and foraminifers for later palaeoenvironmental reconstructions. Canonical correspondence analysis showed that the distribution of the 19 foraminifer and 32 ostracod taxa was controlled mainly by habitat structure, but that specific conductivity (salinity) was best and solely described by the second axis, highlighting the usefulness of the two microfossil groups for salinity reconstructions. Habitat structure was demonstrated by the foraminifer species Trochamminita irregularis’ preference for stillwater areas of lakes. Sarscypridopsis aculeata and Sarscypridopsis glabrata were the dominant ostracod species in coastal ponds and lakes. However, their living distributions excluded each other, with S. aculeata preferring areas of lower salinity and S. glabrata dominating areas of higher salinity up to hyperhaline conditions in small, closed water bodies.

Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

This study presents a comprehensive analytical framework to design efficient single-stage membrane distillation (MD) systems for the desalination of feed streams up to high salinity. MD performance is quantified in terms of energy efficiency (represented as a gained output ratio, or GOR) and vapor flux, both of which together affect the specific cost of pure water production. Irrespective of the feed salinity, permeate or conductive gap MD (P/CGMD) perform better than direct contact MD (DCMD) when the heat transfer resistance of the gap (in P/CGMD) is lower than that of the external heat exchanger in DCMD. Air gap MD’s (AGMD) better performance relative to the other configurations at high salinity and large system area can be explained in terms of its thicker ‘effective membrane’, which includes the air-gap region. CGMD and DCMD employing a thick membrane are also resilient to high salinity, similar to AGMD, while not being susceptible to the gap flooding that can harm AGMD’s performance. A method is described to simultaneously determine the cost-optimal membrane thickness and system size as a function of the ratio of specific costs of heat energy and module area. At low salinity and small system size, GOR rises and flux declines with an increase in membrane area. For salty feed solutions, there exists a critical system size beyond which GOR also begins to decline. Since both GOR and flux are lower, no economic rationale favors operation above this critical size, irrespective of the costs of thermal energy and system area. A closed-form analytical expression for this critical system area is derived as a function of the feed salinity and two dimensionless ratios of heat transfer resistances within the MD module.

Transcriptome analysis of Crossostephium chinensis provides insight into the molecular basis of salinity stress responses.

Soil salinization is becoming a limitation to the utilization of ornamental plants worldwide. Crossostephium chinensis (Linnaeus) Makino is often cultivated along the southeast coast of China for its desirable ornamental qualities and high salt tolerance. However, little is known about the genomic background of the salt tolerance mechanism in C. chinensis. In the present study, we used Illumina paired-end sequencing to systematically investigate leaf transcriptomes derived from C. chinensis seedlings grown under normal conditions and under salt stress. A total of 105,473,004 bp of reads were assembled into 163,046 unigenes, of which 65,839 (40.38% of the total) and 54,342 (33.32% of the total) were aligned in Swiss-Prot and Nr protein, respectively. A total of 11,331 (6.95%) differentially expressed genes (DEGs) were identified among three comparisons, including 2,239 in ‘ST3 vs ST0’, 5,880 in ‘ST9 vs ST3’ and 9,718 in ‘ST9 vs ST0’, and they were generally classified into 26 Gene Ontology terms and 58 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway terms. Many genes encoding important transcription factors (e.g., WRKY, MYB, and AP2/EREBP) and proteins involved in starch and sucrose metabolism, arginine and proline metabolism, plant hormone signal transduction, amino acid biosynthesis, plant-pathogen interactions and carbohydrate metabolism, among others, were substantially up-regulated under salt stress. These genes represent important candidates for studying the salt-response mechanism and molecular biology of C. chinensis and its relatives. Our findings provide a genomic sequence resource for functional genetic assignments in C. chinensis. These transcriptome datasets will help elucidate the molecular mechanisms responsible for salt-stress tolerance in C. chinensis and facilitate the breeding of new stress-tolerant cultivars for high-saline areas using this valuable genetic resource.

A Framework for Incorporating the Impact of Water Quality on Water Supply Stress: An Example from Louisiana, USA

AbstractWater of poor quality can directly impact the budget of water available for key user groups. Despite this importance, methods for quantifying the impact of water quality on water availability remain elusive. Here, we develop a new framework for incorporating the impact of water quality on water supply by modifying the Water Supply Stress Index (WaSSI). We demonstrate the usefulness of the framework by investigating the impact of high salinity waters on the availability of irrigation water for agriculture in Louisiana. The WaSSI was deconstructed into sectoral components such that the total available water supply could be reduced for a particular demand sector (agricultural irrigation in this example) based on available water quality information. The results for Louisiana highlight substantial impacts on water supply stress for farmers attributable to the landward encroachment of saline surface water and groundwater near the coast. Areas of high salinity near the coast also increased the competition for freshwater resources among the industrial, municipal, and agricultural demand sectors in the vicinities of the municipal areas of Lake Charles, Lafayette, and Baton Rouge, Louisiana. The framework developed here is easily adaptable for other water quality concerns and for other demand sectors, and as such can serve as a useful tool for water managers.

Producción de hojarasca y atributos estructurales del manglar en la Laguna Mecoacán, Golfo de México.

Abstract: Mangroves are tropical species established along topographic gradients in coastal areas, where variations in salinity and flooding periods influence the composition and characteristics of primary productivity. In this paper the structural attributes and litter production of mangroves of the Mecoacan lagoon, Gulf of Mexico were evaluated. In six monitoring sites the floristic composition, diameter at breast height (DBH), height, density mature mangrove trees, juveniles, recruits and seedlings, extraction and mortality were determined. Besides, basal area, importance value index (IVI), coverage and Holdridge complexity index, were calculated. Productivity litter of different mangrove species was quantified by trapping capture, while the physico-chemical parameters in surface, interstitial and groundwater were determined by installing piezometers. The study sites in Mecoacan lagoon were classified into two physiographic types: fringe (Boca, Aspoquero, Arrastradero and Pajaral) and basin (Cerros and Mojarrero). 2 854 mature mangrove trees were measured, where 93% belonged to living trees, 4.4% of extracted trees, and 2.6% dead trees standing. The average density was 2 870 mature mangrove trees ha-1. The highest basal area was found in Pajaral (41.7 m-2 h-1). Avicennia germinans (L.) Stearn presented IVI values higher everywhere, for its high relative density. An average cover of 17.5 m2 was registered. The highest rate in complexity was registered in Cerros (27.5). The species showed zonation with salinity levels of interstitial water; A. germinans located in areas of high salinity (hypersalines) while Laguncularia racemosa (L.) Gaertn and Rhizophora mangle L. in areas of lower salinity. Litter production was 5.15 t ha-1 yr-1, it showed a positive correlation with rainfall and high negative correlation with salinity levels and ORP interstitial and groundwater. Results indicate that variability in the composition and structure of mangrove the Mecoacan, is locally determined by the ability to adapt to environmental conditions (salinity, redox potential) and interspecific relationships of the species present.

Invasions in Marine Communities: Contrasting Species Richness and Community Composition Across Habitats and Salinity

While many studies of non-native species have examined either soft-bottom or hard-bottom marine communities, including artificial structures at docks and marinas, formal comparisons across these habitat types are rare. The number of non-indigenous species (NIS) may differ among habitats, due to differences in species delivery (trade history) and susceptibility to invasions. In this study, we quantitatively compared NIS to native species richness and distribution and examined community similarity across hard-bottom and soft-sediment habitats in San Francisco Bay, California (USA). Benthic invertebrates were sampled using settlement panels (hard-bottom habitats) and sediment grabs (soft-bottom habitats) in 13 paired sites, including eight in higher salinity areas and five in lower salinity areas during 2 years. Mean NIS richness was greatest in hard-bottom habitat at high salinity, being significantly higher than each (a) native species at high salinity and (b) NIS richness at low salinity. In contrast, mean NIS richness in soft-bottom communities was not significantly different from native species richness in either high- or low-salinity waters, nor was there a difference in NIS richness between salinities. For hard-bottom communities, NIS represented an average of 79% of total species richness per sample at high salinity and 78% at low salinity, whereas the comparable values for soft bottom were 46 and 60%, respectively. On average, NIS occurred at a significantly higher frequency (percent of samples) than native species for hard-bottom habitats at both salinities, but this was not the case for soft-bottom habitats. Finally, NIS contributed significantly to the existing community structure (dissimilarity) across habitat types and salinities. Our results show that NIS richness and occurrence frequency is highest in hard-bottom and high-salinity habitat for this Bay but also that NIS contribute strongly to species richness and community structure across each habitat evaluated.

The role of connectivity and physicochemical conditions in effective habitat of two exploited penaeid species

The value of estuarine habitats is often measured by their contribution to the adult component of the population, but a broader suite of attributes can also contribute to nursery function. Identifying and quantifying these elements allows habitat repair to be effectively targeted toward improving ecosystem function for desirable species. We present a study that incorporates stable isotopes and quantitative sampling to investigate the relative importance of different estuarine areas for juveniles of exploited prawn species within the context of habitat rehabilitation, and the potential drivers of these relationships. Eastern King Prawn (Penaeus [Melicertus] plebejus) and School Prawn (Metapenaeus macleayi) were studied for two years in the lower Hunter River estuary, on the temperate east coast of Australia. The higher salinity areas near the lower end of the estuary were most important for Eastern King Prawn, and marsh systems in the lower estuary were only important for the species where there was good connectivity with oceanic water. Areas along the estuary were important for juvenile School Prawn, especially marsh habitats, and relative abundance tended to increase with increasing distance along the estuary. Designation of effective juvenile habitat for School Prawn may have been affected by high fishing mortality in fished areas, but this requires further investigation. Salinity, depth, turbidity and distance along the estuary were all important indicators of prawn distribution. The implications of these patterns for current and future habitat rehabilitation in temperate Australia are discussed.

Biodiversity Assessment of Foxtail Millet (Setaria italica L.) Genotypes Based on RAPD Marker

Foxtail millet (Setaria italica L.) is an important crop in areas where harsh environmental conditions limit crop productivity, including in high salinity and drought prone areas. In Indonesia millet is cultivated in certain areas; however, superior varieties are less developed in the country. The objective of this study was to analyze the genetic diversity among foxtail genotypes using RAPD markers. Genomic DNA of ten foxtail millet genotypes was amplified using 26 random primers through RAPD analysis. Of these primers, 22 produced reproducible amplicons and were polymorphic among the 10 foxtail millet genotypes. The number of polymorphic markers for each primer varied from 1 (primer E15) to 14 (primer M17). The amplified product size ranged from 120 to 2500 base pairs (bp). A dendrogram constructed based on the UPGMA clustering method put all genotypes in 5 distinct groups at 0.64 coefficient level. Diverse genotypes identified in this study can be used as potential parents in an efficient crop improvement program.

不同生长时期碱蓬在Pb<sup>2+</sup>、Cd<sup>2+</sup>单一及复合胁迫下的生理生化响应

由于人类活动及工业化的迅速发展，沿海滩涂湿地正在遭受前所未有的污染和破坏，其中铅、镉污染是主要的污染之一，而碱蓬有较强的重金属耐受性和耐盐性，在修复污染的同时也具有较高的经济价值。为研究不同生长时期碱蓬在Pb2+、Cd2+胁迫下的生理生化响应，采用蛭石室外培养，对碱蓬进行Pb2+、Cd2+单一及复合污染处理，结果表明：Pb2+、Cd2+单一及复合胁迫下，碱蓬幼苗期与花期的株高、超氧化物歧化酶(SOD)活性、脯氨酸(Pro)含量、丙二醛(MDA)含量均呈显著差异(P<0.05)。碱蓬在抵御外界Pb2+、Cd2+胁迫时，以SOD活性的快速响应为先，Pro的渗透调节抵御为后，MDA的无序变化实时表征植物的受损状况。总之，碱蓬对Pb2+、Cd2+的胁迫有较强的自我调节能力，具有修复Pb2+、Cd2+污染的潜力，这为进一步利用盐生植物碱蓬修复滨海滩涂等高盐碱土壤，以及抵御Pb2+、Cd2+等重金属复合污染的损伤机制研究提供了理论依据。 Due to the rapid development of human activities and industrialization, tidal wetlands are suffering from unprecedented pollution and destruction b which lead and cadmium pollution is one of the heavy metal pollution. While Suaeda salsa has strong heavy metal tolerance, in the removal of pollution at the same time also has high economic value. In order to study the growth and physiological and biochemical responses of Suaeda salsa under different Pb2+ and Cd2+ concentration, the plant was cultured by vermiculite outdoors, single and combined pollution of Pb2+ and Cd2+ was carried out. The results showed that the plant height and contents of SOD, Pro and MDA in seedling stage and flowering stage of Suaeda salsa were significantly different. When the Suaeda salsas were responded to the Pb2+, Cd2+ single and combined stress, SOD activities responded quickly at first, Pro’s osmotic adjustment would be activated after SOD, the disorderly MDA contents real-time indicated the damaged conditions of cell membrane. In conclusion, Suaeda salsa had strong self-adjustable mechanism when under the Pb2+, Cd2+ stress treatment and which have potential for restore the Pb2+, Cd2+ pollution, which provide a theoretical basis for injury mechanism in which halophytes Suaeda salsa restore high saline areas, such as coastal wetlands and resist the heavy metals contamination.

Population Structure of Adult Blue Crabs, Callinectes sapidus, in Relation to Physical Characteristics in Barnegat Bay, New Jersey

Blue crabs (Callinectes sapidus) are an important species in coastal or lagoonal estuaries where adult population characteristics may differ as compared to drowned-river estuaries. Barnegat Bay, in southern New Jersey, is composed of two large embayments: one without and one with a salinity gradient. We tested the influence of physical characteristics on the abundance, sex ratio, and size of adult blue crabs and examined variation in measures of reproductive potential (e.g., sperm stores) in both sexes in Barnegat Bay from June to September, 2008–2009. Population structure was distinct between the embayments due to sex-specific responses to salinity: male abundance was negatively correlated with salinity whereas adult females were more abundant in high salinity because of proximity to Barnegat Inlet. This produced high sex ratios in low salinity areas and low sex ratios in high salinity areas. Summer was a growing season for adult males while in late summer-early fall, juvenile males recruited to the adult size class. The spawning season lasted from May to August and ovigerous females were concentrated near the inlets. Information on female sperm stores and ovarian development identified two cohorts of adult females: females that will spawn in the current summer and females that will not spawn until the following summer. Thus, not all adult females near the spawning grounds were members of the current spawning stock. This suggests that annual estimates of spawning stock size which overlook the proximity of females to spawning are overestimating the current spawning stock in Barnegat Bay and other estuaries.

Assessment of soil and source water characteristics of disused shrimp ponds in selected coastal states of India and their suitability for resuming aquaculture

The key objective of this study was to assess the suitability of soil and source water quality of abandoned shrimp farms in selected coastal states of India, for resuming aquaculture activities. Soil samples along with associated source water were collected from 60 disused shrimp ponds in different districts of Andhra Pradesh, Tamil Nadu, Odisha and Kerala and analysed for basic physico-chemical parameters. Results of the analysis indicated that the reason for disuse might be reduction in price/repeated occurrences of diseases and that the sampled farms are suitable for aquaculture use. Most of the soil in Andhra Pradesh and Tamil Nadu are suitable for aquaculture without any remediation. Few ponds in Jagatsingpur and Puri districts of Odisha and Kerala needs simple remediation measures like application of lime to increase the soil pH. Source water in Tamil Nadu, Andhra Pradesh and Odisha (Harishpur Creek, Budhabalanga Creek and the coastal canal) fall under high saline areas and are suitable for culture of tiger shrimp Penaeus monodon, white shrimp Litopenaeus vannamei and finfishes like Asian seabass Lates calcarifer and mullets whereas, Kerala and northern parts of Chilka Lake of Odisha fall under low saline areas and are suitable for culture of white shrimp L. vannamei and pearlspot Etroplus suratensis.