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1.
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.  相似文献   

2.
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.  相似文献   

3.
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.  相似文献   

4.
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.  相似文献   

5.
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  相似文献   

6.
We present electron microscopic observations on fragments of encysted embryos of the crustacean,Artemia sp., recovered from a 27,000 year-old core section taken under the Great Salt Lake (GSL), Utah. The significance of these results comes from a consideration of the geological history of the GSL and the extraordinary properties and abundance ofArtemia cysts at this site. We make the case that this unique system, and probably other salt lakes as well, provides novel opportunities for the study of “ancient DNA” and related matters. The analysis provides the major focus of this paper, which we hope will stimulate interest in this aspect of salt lake research.  相似文献   

7.
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.  相似文献   

8.
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.  相似文献   

9.
Amplified Fragment Length Polymorphism (AFLP) markers were successfully employed to analyze 15Artemia species and strains for genetic diversity. AFLP markers are extremely sensitive to even a small sequence variation. They are stable and more polymorphic than RAPD. Twelve pairs of primer combinations were used to detect AFLP bands, of which 384 were polymorphic, and DNA fingerprintings were obtained by using silver staining. The polymorphism analysis leads us to the following conclusions: 1.Artemia tibetiana seems to differentiate fromA. sinica. 2. The parthenogenetic populations from inland salt lakes could follow an evolutionary path that is different from that of the coastal parthenogenetic populations.  相似文献   

10.
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.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
Diatom resting spores are a widespread, but sometimes misconstrued component of siliceous microfossil assemblages. We illustrate and discuss resting spore morphology found in populations ofAcanthoceras andUrosolenia, two widely distributed freshwater genera. Taxonomic status of these genera and the potential paleolimnologic interpretation of resting spores are discussed.  相似文献   

14.
To evaluate the effects of sulphonamide pollution in marine and brackish systems, and to assess the utility of a recently proposed test protocol, sulphadimethoxine toxicity was measured using naupli and cysts of anArtemia species. Nauplii mortality, evaluated between 24 and 96 h, indicated a relatively high toxicity of sulphadimethoxine toArtemia (96 h LC50= 19.5 mg L−1). In addition, test on cysts demonstrated that a nominal concentration of 300 mg L−1 sulphadimethoxine significantly depressed hatching. Toxicity could depend on the high bioaccumulation rate of sulphadimethoxine measured in the organisms. The role of these tests in assessing the environmental risks of intensive farming and in determining suitable standards to improve water quality criteria is discussed together with the possible utilization of bioaccumulatingArtemia as ‘medicated feed’.  相似文献   

15.
Ecological studies onArtemia are still sparse, particularly in the Mediterranean area. The paper provides information on the main life-history traits of a bisexualArtemia strain in solar saltworks at Sant'Antioco, in the Province of Cagliari (southern Sardinia, Italy). Data on age class composition, reproductive mode and status, fecundity and other features are discussed in relation to environmental conditions and compared with previous studies.  相似文献   

16.
A case of parasitism byFlamingolepis liguloides on anArtemia population from south-western Sardinia is noted and discussed. Larval parasites are most frequently located on the host body in the thorax of juveniles and abdomen of older individuals. By contrast, the number of cysticercoids per anatomical area does not seem to be related to host size. Low prevalence of the parasite within the brine shrimp population recorded for a very limited period is assumed to result from the erratic presence of flamingos in the pond.  相似文献   

17.
Five captive adult female degus (Octodon degus) were offered leaves and twigs to eat from three woody (Adesmia bedwellii,Porlieria chilensisandProustia pungens) and two suffruticose (Baccharis paniculataandChenopodium petiolase) shrubs that provide cover in their natural habitat. The degus discriminated among the plant species, consuming lower amounts ofP. chilensis. Daily body mass losses of degus were significantly higher when they were fed uponP. pungensandP. chilensis. The nutritional value of plants, concomitant with degu nutritional requirements, may explain changes in shrub cover previously found to follow removal of degus from experimental plots.  相似文献   

18.
The structure of the naturally occurringArtemia parthenogenetica population inhabiting the Mahalewaya Saltern in Sri Lanka was studied over an annual cycle, together with accompanying variations in the physico-chemical characteristics of its pond waters.Artemia was found only in the serially connected earthen ponds that serve as condenser pans in the saltern. Over the 12-month period of study, salinities in these ponds ranged from 81.5 to 199.6 ppt, temperatures from 28.2 to 33.6°C, pH from 7.9 to 9.1 and dissolved oxygen from, 1.1 to 9.0 mg L–1. The physico-chemical characters varied along a gradient across the three ponds, with salinity and temperature increasing with proximity of the condenser pans to the crystallizers of the saltern and dissolved, oxygen values showing the opposite trend. The ponds containingArtemia were shallow and had a maximum depth of 37 cm. Gross primary productivity ranged from negative values to 686.4 mg C m–2 day–1. Rainfall was distributed non-uniformly almost throughout the year, most of it being experienced from August to October, with a 254 mm maximum in October and lesser rainfall from December to May. Population numbers ranged from zero to 125 individuals L–1 and declined with increasing salinities and temperatures which related, spatilly, to increasing proximity of ponds to crystallizers and temporally, to the dry weather periods. Recruitment was best at low salinities and temperatures (104 to 114 ppt and 28.2 to 30.5°C) but also took place, although, at reduced intensities, up to 174 ppt salinity and 32.2°C temperature. Populations were mostly dominated by instar I stage nauplii with adult stages predominating only during periods of high salinity and temperature. Water management practices for salt production in the salterns included maintaining shallow depths that lead to high water temperatures and pond irrigation procedures that resulted in abrupt salinity changes. Such practices limited the size of theArtemia population as well as prevented its spread into the numerous ponds of the saltern.  相似文献   

19.
Paleolimnological analyses of Chaoborus mandibles were used to assess the status of fish populations over the previous 150 to 300 years in five lakes from the Adirondack region of New York State. Windfall Pond (pH 6.5) has not acidified and currently has viable fish populations. Big Moose Lake (pH 5.0) has acidified in recent years, and the number of fish populations declined from 14 in the 1930's to seven in the early 1980's. The occurrence of only migratory Chaoborus (subgenus Sayomyia) in the cores indicated the long term presence of fish populations in Windfall Pond and Big Moose Lake. Brooktrout Lake (pH 5.0), Deep Lake (pH 4.7) and Upper Wallface Pond (pH 4.8) have all acidified in recent years, and all three are currently fishless. Chaoborus (Sayomyia) was present throughout the Brooktrout Lake core, but the entirely limnetic species, C. americanus, appeared in the topmost interval in the core. The appearance of C. americanus in the top of the core indicated a recent elimination of fish from Brooktrout Lake, probably during the 1970's. Elimination of fish by the 1940's was inferred for Deep Lake because C. americanus appeared above the 1930 level and replaced C. trivittatus as the dominant. Dominance of C. americanus throughout the Upper Wallface Pond core indicated that planktivorous fish were never present. These results strongly suggest that stratigraphic analyses of Chaoborus mandibles provide a useful assessment of the general status of historical fish populations in Adirondack lakes. The technique should be useful in other regions, as well as for applications other than those concerning lake acidification.This is the eleventh of a series of papers to be published by this journal which is a contribution of the Paleoecological Investigation of Recent Lake Acidification (PIRLA) project. Drs. D.F. Charles and D.R. Whitehead are guest editors for this series.  相似文献   

20.
Domestication of wild plants needs efforts focused particularly on the development of the theoretical basis of plant responses to environmental conditions. The objective of this study was to assess the effect of radiation on seedling growth and physiology of Prosopis alba, P. chilensis, P. flexuosa and P. glandulosa. Seedlings were grown in a greenhouse and randomly assigned to three light environments: full-sun, 52% sun, and 38% sun. No significant differences were found in the rate of leaf appearance and plant height 60 days after the light treatments began. Instantaneous CO2uptake was not affected by the light environment during leaf development and did not differ among species. Variations in radiation availability resulted in significant differences in biomass accumulation, shoot/root ratio, protein and total non-structural carbohydrates contents. The practice of shading seedlings reduces the chances of survival ofProsopis due to an increase of the shoot/root ratio and a reduction of total biomass, stored carbohydrates, and the C:N balance.  相似文献   

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