Preliminary characterization of some Argentinean Artemia populations from La Pampa and Buenos Aires provinces

Artemia populations were sampled in four hypersaline ecosystems in continental evaporitic basins from the Argentinean provinces of La Pampa and Buenos Aires. Biometrics of cysts and nauplii were performed. The morphometrics of adult females under standard culture conditions, studied by multivariate discriminant analysis, provided evidence that these populations belonged to the speciesA. persimilis; this was further supported by cross-breeding tests established between one of these populations (Salinas Grandes de Hidalgo, province of La Pampa) and a population ofA. franciscana from San Francisco Bay (California, USA), which showed reproductive isolation and barriers to gene flow between both populations.     

Divergence of Parartemia and Artemia haemoglobin genes

Parartemia is a genus of brine shrimp endemic to Australia which is related to the more widespread and economically importantArtemia sp. The expression of a multimeric haemoglobin molecule inArtemia is well documented but inParartemia only trace levels of a possible haemoglobin have been observed. In this paper we describe the DNA sequence of a domain of a haemoglobin molecule inParartemia. The derived amino acid sequence suggests that the possible date of divergence about 85 million years ago of the two genera predates the divergence of the C and T polymers ofArtemia haemoglobin. This date would correlate with the physical and temporal isolation of Australia in the late Mesozoic.     

Artemia parthenogenetica in Lake Hayward, Western Australia. I. Interrupted recruitment into adult stages in response to seasonal limnology

Lake Hayward, Western Australia, is a pristine, monomictic coastal lake with a residual brine (depth=1.5 m) of 200 gL⁻¹: stratification in winter (May to October) followed the input of ground water and rain. The epilimnion had temperature ranges of 10–30°C, and salinity from 65–110 g L⁻¹. Maximum depth in winter was 2.4 m. The population structure of the brine shrimpArtemia parthenogenetica, the dominant metazoan grazer in Lake Hayward, was studied from September, 1989, to February, 1991. The L. Hayward population ofA. parthenogenetica is predominantly ovoviviparous with little recruitment into the adult population. Cyst production occurs in summer, and there was evidence for recruitment from cyst hatching in the winters of 1989 and 1990. Nauplii were continuously present throughout the study period. Nevertheless, recruitment through to adult stages as defined by the presence of gravid females occurred only twice: in October–December, 1989 and in December, 1990. Based on limited observations of long-term survival of laboratory cultures, we believe that the major mechanism controlling nauplius survival and recruitment ofArtemia in Lake Hayward is food quality and quantity.     

Artemia parthenogenetica in Lake Hayward, Western Australia. II. Feeding biology in a shallow, seasonally stratified, hypersaline lake

Primary production in Lake Hayward, Western Australia, is dominated by benthic microbial communities, with limited planktonic primary production. This study investigated the question of howArtemia, commonly regarded as simple, obligate, non-selective filter feeders, were able to survive in this system. Bacteria (heterotrophic and autotrophic, filamentous and unicellular) were the major components in the diet of theArtemia in Lake Hayward. These bacteria were derived from bacterial aggregates in the water column and also from benthic mat material (both still attached to the substrate and from pieces floating in the water column). Benthic diatoms were a substantial dietary component of animals living in the unstratified shallow regions. Photosynthetic eukaryotic nanoplankton comprised a minor component of the diet of thisArtemia population. Gut contents of a large number of animals and the results of a simple laboratory test indicated that these animals utilise substrate-bound food resources. The results of the present study raises the question of the ecological significance of surface grazing by brine shrimps in other shallow, benthos dominated saline systems.     

Identification of Kalidium species (Chenopodiaceae) by DNA barcoding

DNA barcoding is an increasingly prevalent molecular biological technology which uses a short and conserved DNA fragment to facilitate rapid and accurate species identification. Kalidium species are distributed in saline soil habitat throughout Southeast Europe and Northwest Asia, and used mainly as forage grass in China. The discrimination of Kalidium species was based only on morphology-based identification systems and limited to recognized species. Here, we tested four DNA candidate loci, one nuclear locus (ITS, internal transcribed spacer) and three plastid loci (rbcL, matK and ycf1b), to select potential DNA barcodes for identifying different Kalidium species. Results showed that the best DNA barcode was ITS locus, which displayed the highest species discrimination rate (100%), followed by matK (33.3%), ycf1b (16.7%), and rbcL (16.7%). Meanwhile, four loci clearly identified the variant species, Kalidium cuspidatum (Ung.-Sternb.) Grub.var. sinicum A. J. Li, as a single species in Kalidium.     

Bisexual populations of the brine shrimpArtemia in Sète-Villeroy and Villeneuve Saltworks (Languedoc,France)

So far,Artemia populations in solar saltponds of southern France have been considered as belonging to the Old World parthenogenetic strain. However, two populations sampled monthly in abandoned salinas of Sète-Villeroy and Villeneuve appear to be bisexual throughout their life-cycle. Their sex ratio regularly fluctuates near equilibrium, and mating, present throughout life, is very common in early winter. Morphological characteristics, particularly the male frontal knobs structure, are discussed in relation to the diploid bisexual Mediterranean strain,Artemia tunisiana, which is distributed around the Mediterranean basin. The existence of sexual populations is discussed in regard to variation in environmental conditions in abandoned salinas.     

Characterization of two newArtemia populations from two solar saltworks of Lesbos Island (Greece): biometry,hatching characteristics and fatty acid profile

Cysts of two parthenogeneticArtemia strains from the Kalloni and Polychnitos saltworks on Lesbos Island were evaluated for their potential use in aquaculture. The characterizations performed were: cyst and naupliar biometrics, cyst hatching characteristics, and fatty acid profile of instar-I nauplii. Deactivation of diapause after treatment with H₂O₂ and/or decapsulation were applied in order to improve cyst hatchability. The evaluation revealed that the strains studied exhibit acceptable hatching characteristics for parthenogeneticArtemia and that the fatty acid profile of the Kalloni strain is excellent for use in culturing marine fishes and crustaceans. Statistical analyses on cyst and naupliar biometrics showed that the two populations characterized are almost identical and very similar to other Greek parthenogenetic strains.     

International study onArtemia. LI. New survey ofArtemia resources in the People's Republic of China

We have surveyed 7 inland salt lakes and 14 coastal saltworks in the People's Republic of China (P. R. China) which are natural habitats for the brine shrimpArtemia. We report here on the location of the lakes, the mode of reproduction of theArtemia and the opportunities for achieving self sufficiency in cyst production for use in the local aquaculture industry. Because of frequent misunderstandings regarding the identification of a specific habitat, a new identification system for each population is proposed, using a numerical code which identifies the province, the habitat and the date of collection. Information of newArtemia populations is included as well as data on their reproduction mode.International interdisciplinary study onArtemia populations coordinated by the Laboratory of Aquaculture &Artemia Reference Center, University of Ghent, Belgium.     

International study onArtemia. L. Review of the literature onArtemia from salt lakes in the People's Republic of China

This literature survey covers data on the distribution, genetics and biology ofArtemia from the People's Republic of China (P. R. China) and the use of the brine shrimp in aquaculture and salt production. The vastness of the territory, the unfamiliar geography and the diversity of the habitats, have often lead to ambiguities and contradictions, leaving a gap in our knowledge about the Chinese populations ofArtemia. However, information aboutArtemia from P. R. China has recently become available and this is an attempt to summarize it.International interdisciplinary study onArtemia populations coordinated by the Laboratory of Aquaculture &Artemia Reference Center, University of Ghent, Belgium.     

Amelioration of soil fertility by woody perennials in cropping fields: evaluation of three tree species in the semi-arid zone of Nigeria

Soil was sampled from cropping fields in radial patterns from beneathAcacia albida, Parkia bigloboza(Jacq.) Benth. andEucalyptus camaldulensisDehnh. near Zaria, Nigeria. Results of analysis show a significant coarsening of soil texture and a decrease in organic matter and cation exchange capacity with increasing distance from all three tree species at a depth of 0–15 cm. Concentrations of nitrogen and some exchangeable cations decreased significantly with increasing distance from beneath acacia and parkia, and soil pH decreased with increasing distance from eucalyptus. The implication of the results for land management are discussed in relation to increasing productivity and soil use sustainability.     

Hydrobiology of some solar salt works in India

The hydrobiology of two Indian solar salt works was investigated. A salient feature was variability in physico-chemical and biological characteristics. The filamentous cyanophyceansLyngbya majuscula andOscillatoria salina and the chlorophyceanXenococcus aceervatus were the major primary producers. Significant fauna were protozoans, rotifers and copepods.Artemia was present in only one set of solar salt pans, where it was dominant. The study illustrates the importance ofArtemia in the biological management of solar salt works. This paper is dedicated to Thiru. K. Ayyaru Vandayar, Member, Governing body, A.V.V.M. Sri Pshpam College (Autonomous), Poondi, on his sixtieth birthday     

Salinity-induced growth and some metabolic changes in three Salsola species

Three Salsola species, Salsola dendroides Pall., S. richteri (Moq.) Karel ex Litw. and S. orientalis S.C. Gmel., were compared for their salt tolerance, inorganic ionic accumulation and their biomass production in saline conditions. Seeds were grown on sterilized quartz under five salinity levels in a factorial experimental design, with four replications, in greenhouse conditions.With salinity, Na⁺ accumulation increased while K⁺ accumulation decreased. All three species showed positive shoot growth for low levels of salinity. Root growth showed almost the same trend as shoot growth, with minor exceptions. At low levels of salinity, proline accumulated more in S. dendroides plant tissues than in the tissues of the other two species. These results suggest that the proline accumulation is a good index for salinity tolerance. Soluble sugars also increased as a result of salinity.     

Artemia tibetiana: preliminary characterization of a new Artemia species found in Tibet (People's Republic of China). International Study on Artemia. LIX

In this study, we report on the existence of a new bisexual Artemia species, found in the high plateaus of Tibet (P. R. China). Different disciplines have been used to characterize this new population: biometrics of cysts and nauplii, morphometry of adults, cytogenetics, allozyme and DNA analyses and cross-breeding/fertility tests with known Artemia species. The results obtained justify that there is enough evidence to support the view that Artemia from Tibet is a new species with the proposed name Artemia tibetiana.     

Carbon and nitrogen isotopic composition of different strains ofArtemia sp

Stable carbon and nitrogen isotope ratios have been determined on 41 strains ofArtemia sp. from different geographic regions around the world. The δ¹³C and δ¹⁵N values ranged between −13.7 to−25.0 per mil and −0.7 to 21.2 per mil respectively.Artemia δ¹³C values from coastal environments are consistent with a marine origin for the food sourceArtemia from inland salt lakes have a range of carbon isotope values suggesting C₃, C₄ and CAM based organic matter could form the base of theArtemia food chain. These data indicate thatArtemia having a wide range of carbon and nitrogen isotope values are available for tropho-dynamic research studies that quantify the effect of respired CO₂ on tissue and CaCO₃ shell¹³C/¹²C ratios. Such stable isotope variation also suggests that stable isotope fingerprinting remains a viable technique for identifying specificArtemia collection sites.     

Limnological studies of Amarga Lagoon,Chile: A saline lake in Patagonian South America

Amarga Lagoon, lat. 50°29 S and long. 73°45 S, it is located at the Torres del Paine National Park, Chile. The physical, chemical, and biological features of the lake were studied. According to salinity, the lake is mesosaline. Sodium and chloride were the dominant ions. Nitrogen was potentially limiting for phytoplankton growth. One Cyanophyceae species andArtemia were the predominant species in the plankton.Artemia provided abundant food for flamingoes.     

Seed germination of five mountain steppe species of Central Asia

This paper presents data on the germination traits of five perennials (Allium polyrrhizum, Agropyron cristatum, Arenaria meyeri, Artemisia frigida and Artemisia santolinifolia) widespread in the mountain steppes of southern Mongolia. Germination and seed viability were assessed at three alternate temperatures (8/4 °C, 20/10 °C, 32/20 °C), three levels of osmotic stress (deionized water; −0.5 MPa, −1 MPa Mannitol solution), and under conditions of alternate light/darkness versus complete darkness. The results of a factorial ANOVA with treatments and species as main effects showed that all five species germinated best at higher temperatures, with only Agropyron cristatum showing some seed mortality. Osmotic stress reduced seed viability and total germination in all five species. Darkness had no influence on viability, but positively affected seed germination of Allium polyrrhizum and Agropyron cristatum. We therefore conclude that, in the field, germination of all five species is mainly controlled by ambient temperatures and water availability, both of which drop towards the end of summer when dispersal takes place and effectively delay seedling recruitment until the next vegetation period.     

Water requirements for germination and early seedling establishment in four African savanna woody plant species

The aim of this study was to determine the water requirements for germination and early seedling establishment of four African savanna tree species, namelyAcacia karroo, A. nilotica, A. tortilisandMundulea sericea. The acacias are characteristic of nutrient-rich, andM. sericeaof nutrient-poor savannas. Imbibition times of scarified seeds ofA. karroo(4 h),M. sericea(6 h) andA. tortilis(8 h) were rapid relative toA. nilotica(28 h) and were inversely correlated with seed size. Imbibed water is lost in about 2 h after drying at 25°C for all species exceptA. nilotica(only 70% moisture loss). Seeds ofA. karrooandM. sericeakept at 40°C dried to below their original moisture contents within 2 h. Seeds ofA. niloticaandA. tortilisdried at 40°C lost viability relative to (undried) control seeds, while there was no significant loss of viability forA. karrooandM. sericea. For fully imbibed seeds to germinate in sandy savanna soils, all four species required at least the equivalent of 3 mm rainfall every 2 days under mild greenhouse conditions. However, most ungerminated seeds were still viable despite drying-out from a fully imbibed state. Maintenance of soil at 50% field capacity (FC), or watering to FC every 9th day is the maintenance requirements for 2-week-old seedlings ofA. niloticaandM. sericeato continue growth for a further 5 weeks under greenhouse conditions, althoughA. niloticamostly survived 25% FC with one seedling surviving 12·5% FC. Root penetration was rapid in sandy soils, withA. niloticaandM. sericeaattaining a depth of 40 cm within 15 days. Frequent, but not necessarily high, rainfall appears to be essential for germination and seedling survival over the first 7 weeks.     

Biogeography of the genusArtemia (Crustacea,Branchiopoda, Anostraca) in Spain

This is an updated study on the biogeographic distribution of the populations of the genusArtemia (Branchiopoda, Anostraca) in Spain, with special focus on populations inhabiting salt lagoons and inland salterns. The populations recorded (40) belong to the bisexual speciesA. tunisiana and to the asexual groupA. parthenogenetica (diploid and tetraploid strains). They usually appear in three different hypersaline ecosystems: solar salterns and lagoons filled with sea water, solar salterns and lagoons containing brines of diluted mineral salts, and lagoons filled with athalassic (endorheic) brines. The brines in salinas are chemically characterized by high Cl^– concentrations, especially in inland salinas, whose brine sources are geologically associated with evaporitic formations developed in the Triassic and Lower Liassic of eastern Spain. Brines in athalassic lagoons, geologically associated with Mesozoic and Cenozoic periods, show higher levels of sulfate (up to 40–50%) as well as Mg²⁺. From a geographical point of view, bisexual and diploid asexual populations are mainly found in coastal and inland salinas or lagoons below 40° N, while asexual tetraploid populations are found in inland salinas and athalassic lagoons above that latitude. These populations have been biologically characterized by the morphology of their adults through multivariate analysis.     

Biological and physical events involved in the origin,effects, and control of organic matter in solar saltworks

Aspects of communities and events in the concentrating ponds (S.G. 1.130 to 1.214) and salt crystallizing ponds (S.G. 1.215 to 1.264) of solar saltworks pertinent to salt manufacture are described. Communities that aid salt manufacture enable continuous and efficient production of high quality salt at a saltworks' design capacity, and they provide important controls on levels of organic matter in the brine. Fluctuating salinities, high concentrations of nutrients, and petroleum products are disturbances that causeAphanothece halophytica andDunaliella salina to release excessive quantities of organic matter, and that suppress or cause death to nutrient stripping organisms. Disturbances result in decreased quality and quantity of salt and increased costs for salt harvest, washing, and pond upkeep. Organic matter can be controlled by management techniques that keep nutrient stripping communities at proper levels and maintain a narrow and unchanging range of salinities in each pond, by constructing pond dikes able to withstand wind and water erosion, and by preventing spills of petroleum products in the ponds.