Saline systems最新文献

{"title":"A biometric and ecologic comparison between Artemia from Mexico and Chile.","authors":"Thalía B Castro,&nbsp;Gonzalo Gajardo,&nbsp;Jorge M Castro,&nbsp;Germán M Castro","doi":"10.1186/1746-1448-2-13","DOIUrl":"https://doi.org/10.1186/1746-1448-2-13","url":null,"abstract":"<p><strong>Background: </strong>A preliminary biometric and ecologic database for the brine shrimp Artemia from Mexico and Chile is presented. The area abounds in small and seasonal ponds and large inland lakes, the latter mainly located in Mexico, although relatively large and isolated lakes are found in complex hydrological settings in pre-high plateau areas of Chile. This paper summarizes research efforts aimed at the localization, characterization, and evaluation of the aquaculture potential of Artemia populations in Mexico and Chile, which exhibit great habitat diversity (ponds, salterns, coastal lagoons, sea arms, coastal and inland lakes), contrasting weather conditions and different levels of isolation and human intervention.</p><p><strong>Results: </strong>This study covered locations between 29 degrees north latitude (Baja California, Mexico) to 50 degrees south latitude (Puerto Natales, Chile). Biological characteristics considered are species name, reproductive mode, cyst diameter, chorion thickness, and nauplius length, whereas ecological data include pond size, pH, salinity, temperature, and water ionic composition. Artemia franciscana is the only species found in Mexico, it exists together with A. persimilis in Chile, though separated geographically. Ecological differences in habitat exist between both regions but also within countries, a pattern particularly clear with regard to water composition. Surprisingly, a Mexican (Cuatro Ciénegas, A. franciscana) and a Chilean location (Torres del Paine, A. persimilis) share habitat characteristics, at least for the period when data were collected. The discriminant analysis for cyst diameter and nauplius length shows that Artemia from only one location match in cyst diameter with those from San Francisco Bay (SFB) (Point Lobos), and one (Marquez) is far apart from SFB and all the others. The Chilean locations (Pampilla, Cejar, Cahuil, Llamara, Yape) share cyst diameter, but tend to differ from SFB. The remaining Mexican locations (Juchitan, Ohuira, Yavaros) are well separated from all the others. With regard to nauplii length, populations tend to distribute in a relatively random manner, being Marquez the location differing the most in cyst diameter from SFB.</p><p><strong>Conclusion: </strong>This database will contribute to the knowledge of radiation centers and serves as a baseline for further biogeographic studies, population characterization, management, and monitoring of Artemia biodiversity. Likewise, the impact of colonization and translocations for aquaculture purposes can be better assessed with a baseline for reference. Mexico and Chile exemplify the need to increase and further integrate regional information to tackle fundamental problems underlying practical utilization of Artemia.</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1746-1448-2-13","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26405972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Response of biotic communities to salinity changes in a Mediterranean hypersaline stream.","authors":"Josefa Velasco,&nbsp;Andrés Millán,&nbsp;Juan Hernández,&nbsp;Cayetano Gutiérrez,&nbsp;Pedro Abellán,&nbsp;David Sánchez,&nbsp;Mar Ruiz","doi":"10.1186/1746-1448-2-12","DOIUrl":"https://doi.org/10.1186/1746-1448-2-12","url":null,"abstract":"<p><strong>Background: </strong>This study investigates the relationship between salinity and biotic communities (primary producers and macroinvertebrates) in Rambla Salada, a Mediterranean hypersaline stream in SE Spain. Since the 1980's, the mean salinity of the stream has fallen from about 100 g L(-1) to 35.5 g L(-1), due to intensive irrigated agriculture in the watershed. Furthermore, large dilutions occur occasionally when the water irrigation channel suffers cracks.</p><p><strong>Results: </strong>Along the salinity gradient studied (3.5-76.4 g L(-1)) Cladophora glomerata and Ruppia maritima biomass decreased with increasing salinity, while the biomass of epipelic algae increased. Diptera and Coleoptera species dominated the community both in disturbed as in re-established conditions. Most macroinvertebrates species found in Rambla Salada stream are euryhaline species with a broad range of salinity tolerance. Eight of them were recorded in natural hypersaline conditions (approximately 100 g L(-1)) prior to important change in land use of the watershed: Ephydra flavipes, Stratyomis longicornis, Nebrioporus ceresyi, N. baeticus, Berosus hispanicus, Enochrus falcarius, Ochthebius cuprescens and Sigara selecta. However, other species recorded in the past, such as Ochthebius glaber, O. notabilis and Enochrus politus, were restricted to a hypersaline source or absent from Rambla Salada. The dilution of salinity to 3.5-6.8 g L(-1) allowed the colonization of species with low salininty tolerance, such as Melanopsis praemorsa, Anax sp., Simulidae, Ceratopogonidae and Tanypodinae. The abundance of Ephydra flavipes and Ochthebius corrugatus showed a positive significant response to salinity, while Anax sp., Simulidae, S. selecta, N. ceresyi, N. baeticus, and B. hispanicus showed significant negative correlations. The number of total macroinvertebrate taxa, Diptera and Coleoptera species, number of families, Margalef's index and Shannon's diversity index decreased with increasing salinity. However, the rest of community parameters, such as the abundance of individuals, evenness and Simpson's index, showed no significant response to changes in salinity. Classification and ordination analysis revealed major differences in macroinvertebrate community structure between hypersaline conditions (76.4 g L(-1)) and the rest of the communities observed at the lower salinity levels, and revealed that below approximately 75 g L(-1), dissimilarities in the communities were greater between the two habitats studied (runs and pools) than between salinity levels.</p><p><strong>Conclusion: </strong>Salinity was the first factor determining community composition and structure in Rambla Salada stream followed by the type of habitat.</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1746-1448-2-12","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26341909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The uvrA, uvrB and uvrC genes are required for repair of ultraviolet light induced DNA photoproducts in Halobacterium sp. NRC-1.","authors":"David J Crowley,&nbsp;Ivan Boubriak,&nbsp;Brian R Berquist,&nbsp;Monika Clark,&nbsp;Emily Richard,&nbsp;Lynn Sullivan,&nbsp;Shiladitya DasSarma,&nbsp;Shirley McCready","doi":"10.1186/1746-1448-2-11","DOIUrl":"https://doi.org/10.1186/1746-1448-2-11","url":null,"abstract":"<p><strong>Background: </strong>Sequenced archaeal genomes contain a variety of bacterial and eukaryotic DNA repair gene homologs, but relatively little is known about how these microorganisms actually perform DNA repair. At least some archaea, including the extreme halophile Halobacterium sp. NRC-1, are able to repair ultraviolet light (UV) induced DNA damage in the absence of light-dependent photoreactivation but this 'dark' repair capacity remains largely uncharacterized. Halobacterium sp. NRC-1 possesses homologs of the bacterial uvrA, uvrB, and uvrC nucleotide excision repair genes as well as several eukaryotic repair genes and it has been thought that multiple DNA repair pathways may account for the high UV resistance and dark repair capacity of this model halophilic archaeon. We have carried out a functional analysis, measuring repair capability in uvrA, uvrB and uvrC deletion mutants.</p><p><strong>Results: </strong>Deletion mutants lacking functional uvrA, uvrB or uvrC genes, including a uvrA uvrC double mutant, are hypersensitive to UV and are unable to remove cyclobutane pyrimidine dimers or 6-4 photoproducts from their DNA after irradiation with 150 J/m2 of 254 nm UV-C. The UV sensitivity of the uvr mutants is greatly attenuated following incubation under visible light, emphasizing that photoreactivation is highly efficient in this organism. Phylogenetic analysis of the Halobacterium uvr genes indicates a complex ancestry.</p><p><strong>Conclusion: </strong>Our results demonstrate that homologs of the bacterial nucleotide excision repair genes uvrA, uvrB, and uvrC are required for the removal of UV damage in the absence of photoreactivating light in Halobacterium sp. NRC-1. Deletion of these genes renders cells hypersensitive to UV and abolishes their ability to remove cyclobutane pyrimidine dimers and 6-4 photoproducts in the absence of photoreactivating light. In spite of this inability to repair UV damaged DNA, uvrA, uvrB and uvrC deletion mutants are substantially less UV sensitive than excision repair mutants of E. coli or yeast. This may be due to efficient damage tolerance mechanisms such as recombinational lesion bypass, bypass DNA polymerase(s) and the existence of multiple genomes in Halobacterium. Phylogenetic analysis provides no clear evidence for lateral transfer of these genes from bacteria to archaea.</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1746-1448-2-11","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26251502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NhaD type sodium/proton-antiporter of Halomonas elongata: a salt stress response mechanism in marine habitats?","authors":"Matthias Kurz,&nbsp;Anika N S Brünig,&nbsp;Erwin A Galinski","doi":"10.1186/1746-1448-2-10","DOIUrl":"https://doi.org/10.1186/1746-1448-2-10","url":null,"abstract":"<p><strong>Background: </strong>Sodium/proton-antiporters (Nha) are known to play an important role in pH- and Na+-homeostasis. In microorganisms several types with different capacity, affinity and selectivity for Na+ and Li+ exist. The homeostasis system of E. coli, NhaA and NhaB, is well researched, but the function of other types of Na+/H+-antiporters like NhaD is yet to be fully understood. Since several antiporters play an important role at various points in the physiology of higher organisms, one can speculate that the main functions of some of those procaryotic antiporters differ from pH- and Na+-homeostasis.</p><p><strong>Results: </strong>This study investigates the function and regulation of a gene encoding for a NhaD type antiporter which was discovered in the halophilic eubacterium Halomonas elongata. The deduced primary amino acid sequence of the abovementioned gene showed more than 60% identity to known antiporters of the NhaD type from Alkalimonas amylolytica, Shewanella oneidensis and several other marine organisms of the gamma-Proteobacteria. Evidence was found for a dual regulation of H. elongata NhaD expression. The gene was cloned and expressed in E. coli. Antiporter deficient NaCl and LiCl sensitive E. coli mutants EP432 and KNabc were partially complemented by a plasmid carrying the H. elongata nhaD gene. Surprisingly the LiCl sensitivity of E. coli strain DH5alpha having a complete homeostasis system was increased when NhaD was co-expressed.</p><p><strong>Conclusion: </strong>Since NhaD is an antiporter known so far only from halophilic or haloalcaliphilic Proteobacteria one can speculate that this type of antiporter provides a special mechanism for adaptation to marine habitats. As was already speculated--though without supporting data--and substantiated in this study this might be active Na+-import for osmoregulatory purposes.</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1746-1448-2-10","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26170108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrogeochemistry of seasonal variation of Urmia Salt Lake, Iran.","authors":"Samad Alipour","doi":"10.1186/1746-1448-2-9","DOIUrl":"https://doi.org/10.1186/1746-1448-2-9","url":null,"abstract":"<p><p>Urmia Lake has been designated as an international park by the United Nations. The lake occupies a 5700 km2 depression in northwestern Iran. Thirteen permanent rivers flow into the lake. Water level in the lake has been decreased 3.5 m in the last decade due to a shortage of precipitation and progressively dry climate. Geologically the lake basin is considered to be a graben of tectonic origin. Na, K, Ca, Li and Mg are the main cations with Cl, SO4, and HCO3 as the main anions. F & Br are the other main elements in the lake. A causeway crossing the lake is under construction, which may affect the lake's annual geochemistry. The main object of this project is mainly to consider the potential of K-mineral production along with ongoing salt production. Seven hundred and four samples were taken and partially analyzed for the main cations and anions. Surface water (0.5 m. depth) was analyzed for Na, K, Mg, Ca, Br and Li, and averaged 87.118 g/lit, 1.48 g/lit, 4.82 g/lit, 4.54 g/lit, 1.19 ppm and 12.7 ppm respectively for the western half of the lake. Sodium ranged between 84 to 91.2 g/lit, and showed higher concentrations in the south than in the north. This unexpected result may be caused by shallower depth in the south and a higher net evaporation effect. Calcium ranged between 4.2 to 5 g/lit, apparently slightly higher in the north. K is higher in the south, possibly due to rivers entering from south that may carry slightly higher K in solution. In the middle-range samples (0.5-5 m.), K averaged 1.43 g/lit and ranged from 1.40 to 1.46 g/lit. At this intermediate depth the distribution of K is clearly higher to the south of the causeway that is currently under construction. It is not clear whether this increase is the effect of the causeway or the effect of the salty Aji-Chay River to the east, and the Khoy salt domes to the north of the lake. At depth (5 m-10 m), K averaged 1.48 g/lit and ranged from 1.4 to 1.49 g/lit, differing only in the second decimal from the average of the middle and surface samples. Ignoring the small difference between the averages of the three sample depths, the distribution of K is highly homogeneous in the lake water due to the mixing process. Therefore causeway construction has not yet strongly affected K distribution, or it may be at the starting point. Magnesium concentration ranged from 4.6 to 5-g/lit, and was elevated in the south. This differs somewhat compared to calcium. Lithium, with an average of 12-13 ppm, is slightly higher in the south, and has not shown any significant variation in all three seasons. Iodine was below the detection limit in the lake. Urmia Lake, geochemically, is highly uniform both to the south and north of the causeway, in both the surface and deep brines. K and Mg, which average 1.48 and 6.6 g/lit in order, could be elements worth production in addition to the NaCl currently being produced from the lake. Br, F, Li and B in the limit of <50 ppm don't look to be in the economical rang","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1746-1448-2-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26139599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati.","authors":"Casey Saenger,&nbsp;Michael Miller,&nbsp;Rienk H Smittenberg,&nbsp;Julian P Sachs","doi":"10.1186/1746-1448-2-8","DOIUrl":"https://doi.org/10.1186/1746-1448-2-8","url":null,"abstract":"<p><p>The equatorial Pacific Ocean atoll islands of Kiritimati and Teraina encompass great physical, chemical and biological variability within extreme lacustrine environments. Surveys of lake chemistry and sediments revealed both intra- and inter-island variability. A survey of more than 100 lakes on Kiritimati found salinities from nearly fresh to 150 ppt with the highest values occurring within the isolated, inland portions of the island away from the influence of groundwater or extreme tides. Dissolved oxygen (DO) and pH values also showed considerable variability with a less regular spatial pattern, but were both generally inversely related to salinity. Series of lakes, progressively more isolated from marine communication, present a modern analog to the chemical and morphologic evolution of presently isolated basins. Sediments on both islands consist of interbedded red and green silt, possibly degraded bacterial mat, overlying white, mineralogenic silt precipitate. Variability may be indicative of shifts in climatological parameters such as the El Niño Southern Oscillation (ENSO) or the Pacific Intertropical Convergence Zone (ITCZ).</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1746-1448-2-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26126749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of cyanobacterial extracellular products and gibberellic acid on salinity tolerance in Oryza sativa L.","authors":"A A Rodríguez, A M Stella, M M Storni, G Zulpa, M C Zaccaro","doi":"10.1186/1746-1448-2-7","DOIUrl":"10.1186/1746-1448-2-7","url":null,"abstract":"<p><p>Salt stress is one of the most serious factors limiting the productivity of rice, the staple diet in many countries. Gibberellic acid has been reported to reduce NaCl-induced growth inhibition in some plants including rice. Most paddy soils have a natural population of Cyanobacteria, prokaryotic photosynthethic microorganisms, which synthesize and liberate plant growth regulators such as gibberellins that could exert a natural beneficial effect on salt stressed rice plants. The aim of this work was to evaluate the effect of the cyanobacterium Scytonema hofmanni extracellular products on the growth of rice seedlings inhibited by NaCl and to compare it with the effect of the gibberellic acid in the same stress condition. Growth (length and weight of the seedlings) and biochemical parameters (5-aminolevulinate dehydratase activity, total free porphyrin and pigments content) were evaluated. Salt exposure negatively affected all parameters measured, with the exception of chlorophyll. Chlrorophyll concentrations nearly doubled upon exposure to high salt. Gibberellic acid counteracted the effect of salt on the length and dry weight of the shoot, and on carotenoid and chlorophyll b contents. Extracellular products nullified the salt effect on shoot dry weight and carotenoid content; partially counteracted the effect on shoot length (from 54% to 38% decrease), root dry weight (from 59% to 41% decrease) and total free porphyrin (from 31 to 13% decrease); reduced by 35% the salt increase of chlorophyll a; had no effect on root length and chlorophyll b. Gibberellic acid and extracellular products increased 5-aminolevulinate dehydratase activity over the control without salt. When coincident with high salinity, exposure to either EP or GA3, resulted in a reversal of shoot-related responses to salt stress. We propose that Scytonema hofmanni extracellular products may counteract altered hormone homeostasis of rice seedlings under salt stress by producing gibberellin-like plant growth regulators.</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1513582/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26074343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"International Rotifer Symposia: prospects and retrospects from Rotifera XI.","authors":"S S S Sarma","doi":"10.1186/1746-1448-2-6","DOIUrl":"https://doi.org/10.1186/1746-1448-2-6","url":null,"abstract":"<p><p>The XI International Rotifer Symposium was held during 11-18 March, 2006 at the National Autonomous University of Mexico Campus Iztacala located at the North Mexico City (Mexico). These triennial international meetings, first organized in Austria by Late Ruttner-Kolisko in September 1976, are gradually becoming the focal point of discussion and collaboration from rotifer workers across the world. The present XI symposium was attended by 125 participants from 20 nations. During this meeting, different themes of rotifer research from morphology to molecular biology were considered. In addition, there were four invited lectures and four workshops covering different themes of the symposium. During the last 30 years, rotifer research has witnessed gradual shift from the conventional morphological taxonomy to molecular and evolutionary systematics. While the basic rotifer ecological studies continue today, applied areas such as ecotoxicology and aquaculture have taken key roles in the recent meetings. The international rotifer meetings provide ample opportunities not only for exchange of ideas and recent research, but also for material and in establishing inter-personal relationships. Over the last 30 years, the number of participants attending the rotifer meetings has increased.</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1746-1448-2-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"26025672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cyanobacteria toxins in the Salton Sea.","authors":"Wayne W Carmichael,&nbsp;RenHui Li","doi":"10.1186/1746-1448-2-5","DOIUrl":"https://doi.org/10.1186/1746-1448-2-5","url":null,"abstract":"<p><strong>Background: </strong>The Salton Sea (SS) is the largest inland body of water in California: surface area 980 km2, volume 7.3 million acre-feet, 58 km long, 14-22 km wide, maximum depth 15 m. Located in the southeastern Sonoran desert of California, it is 85 m below sea level at its lowest point. It was formed between 1905 and 1907 from heavy river flows of the Colorado River. Since its formation, it has attracted both people and wildlife, including flocks of migratory birds that have made the Salton Sea a critical stopover on the Pacific flyway. Over the past 15 years wintering populations of eared grebe (Podiceps nigricollis) at the Salton Sea, have experienced over 200,000 mortalities. The cause of these large die-offs remains unknown. The unique environmental conditions of the Salton Sea, including salinities from brackish freshwater at river inlets to hypersaline conditions, extreme daily summer temperatures (>38 degrees C), and high nutrient loading from rivers and agricultural drainage favor eutrophic conditions that encourage algal blooms throughout the year. A significant component of these algal blooms are the prokaryotic group - the Cyanophyta or blue-green algae (also called Cyanobacteria). Since many Cyanobacteria produce toxins (the cyanotoxins) it became important to evaluate their presence and to determine if they are a contributing factor in eared-grebe mortalities at the Salton Sea.</p><p><strong>Results: </strong>From November 1999 to April 2001, 247 water and sediment samples were received for phytoplankton identification and cyanotoxin analyses. Immunoassay (ELISA) screening of these samples found that eighty five percent of all water samples contained low but detectable levels of the potent cyclic peptide liver toxin called microcystins. Isolation and identification of cyanobacteria isolates showed that the picoplanktonic Synechococcus and the benthic filamentous Oscillatoria were dominant. Both organisms were found to produce microcystins dominated by microcystin-LR and YR. A laboratory strain of Synechococcus was identified by PCR as being closest to known marine forms of this genus. Analyses of affected grebe livers found microcystins at levels that may account for some of the acute mortalities.</p><p><strong>Conclusion: </strong>The production of microcystins by a marine Synechococcus indicates that microcystins may be a more common occurrence in marine environments - a finding not recognized before this work. Further research should be done to define the distribution of microcystin producing marine cyanobacteria and to determine exposure/response effects of microcystins and possibly other cyanotoxins in the Salton Sea. Future efforts to reduce avian mortalities and remediate the Salton Sea should evaluate vectors by which microcystins enter avian species and ways to control and mitigate toxic cyanobacteria waterblooms at the Salton Sea.</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1746-1448-2-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25980302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Buoyancy studies in natural communities of square gas-vacuolate archaea in saltern crystallizer ponds.","authors":"Aharon Oren, Nuphar Pri-El, Orr Shapiro, Nachshon Siboni","doi":"10.1186/1746-1448-2-4","DOIUrl":"10.1186/1746-1448-2-4","url":null,"abstract":"<p><strong>Background: </strong>Possession of gas vesicles is generally considered to be advantageous to halophilic archaea: the vesicles are assumed to enable the cells to float, and thus reach high oxygen concentrations at the surface of the brine.</p><p><strong>Results: </strong>We studied the possible ecological advantage of gas vesicles in a dense community of flat square extremely halophilic archaea in the saltern crystallizer ponds of Eilat, Israel. We found that in this environment, the cells' content of gas vesicles was insufficient to provide positive buoyancy. Instead, sinking/floating velocities were too low to permit vertical redistribution.</p><p><strong>Conclusion: </strong>The hypothesis that the gas vesicles enable the square archaea to float to the surface of the brines in which they live was not supported by experimental evidence. Presence of the vesicles, which are mainly located close to the cell periphery, may provide an advantage as they may aid the cells to position themselves parallel to the surface, thereby increasing the efficiency of light harvesting by the retinal pigments in the membrane.</p>","PeriodicalId":87359,"journal":{"name":"Saline systems","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2006-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1459177/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"25972447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}