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The present study reports on population structure analysis of the marbled crabPachygrapsus marmoratus (Fabricius, 1787) from the Tunisian coast, an appropriate location to study biogeographical process... 相似文献
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Well-stratified lacustrine deposits of clay, silt, and marl occur within the rugged mountainous triangle of igneous and metamorphic rocks of Sinai Peninsula, Egypt. These deposits occur only in two sites along Wadi Feiran channel (Feiran and El-Tarfa Oases), where very dense acidic dykes intersect their stream courses. Such dykes played an important role in damming water from torrential rainfall during the humid period to form lakes. The SRTM (90 m) data and high-resolution images (IKONOS) have been utilized to reconstruct the paleolakes in terms of shape, size and water volume. Results show that lake deposits are located where acidic dykes cross narrow channel of high sinuosity. At their former heights, the dykes dammed the surface runoff, thus, three local freshwater paleolakes formed behind them. GIS analysis shows that the largest of these paleolakes was formed in the area of Feiran Oasis. Two other smaller paleolakes were formed at El-Tarfa Oasis due to the presence of two pronounced acidic dykes.These lake deposits were derived mainly from El-Tih Plateau via Wadi El-Akhdar. Another source of these deposits could have been a thin sedimentary cap over the weathered granites northeast of Feiran basin. 相似文献
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Ben Kahla-Nakbi A Besbes A Chaieb K Rouabhia M Bakhrouf A 《Marine environmental research》2007,64(4):469-478
The aim of this study was to evaluate the survival responses of four strains of Vibrio alginolyticus in seawater under starvation conditions. We used microcosms containing sterilised seawater and incubated at ambient temperature (22-25 degrees C). V. alginolyticus maintained its culturability for at least nine months. Long-term-starved cells showed an absence or a decrease in their enzymatic activities. Resuscitation assays of viable but non-culturable (VBNC) cells were conducted and the recovery of these cells was achieved after the addition of nutrients. Amplified 16S ribosomal DNA (rDNA) restriction analysis (ARDRA) was used to confirm that the same strain of V. alginolyticus persisted in all microcosms during a long period of time. Starved cells maintained their infectivity for gilt head sea bream (Sparus aurata) and sea bass (Dicentrachus labrax) as determined by intraperitoneal challenges. 相似文献
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We separated tertiary egg membrane (TGM) from 2- and 25-day-old eggs of cuttlefish Sepiella maindroni de Rochebrune, and revealed its ultrastructure, physical (solubility, barrier property) and biochemical (histology, histochemistry,
nutritional components, bacteriostasis) characteristics. The results show that TGM could not be dissolved with natural seawater,
alcohol, ether or hydrochloric acid (HCl), but it could be dissolved with 2-chloroethanol, diethylamine, and sodium hydroxide
(NaOH). The black TGM was more effective in blocking off mud particulates, microorganisms (Chlorella vulgaris, Vibrio alginolyticus) and lighter than the white TGM. The elasticity of black and white TGMs was 1.8 N and 1.5 N, respectively. There were some
ink particulates and rod-shaped bacteria in the black TGM. The nutritional components were different between black and white
TGMs: Lipid content was lower and protein content was higher in the black TGM. TGM could also inhibit the growth of Vibrio alginolyticus. 相似文献
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The perennial saltgrass nipa (Distichlis palmeri, Poaceae) is endemic to northern Gulf of California tidal marshes flooded with hypersaline (38–42 g L−1) seawater. Nipa was a wild harvest staple of the Cocopah people of the Río Colorado delta. We investigated the physiology, anatomy, chromosome number, and agronomic potential of nipa as a global food crop. Nipa seeds had 60–93% germination on salinities ranging from 0 to 30 g L−1. Relative Growth Rates (RGR) on both flooded and aerobic conditions remained above 4% d−1 up to 30 g L−1, about half the RGR on freshwater. Nipa grain (caryopses) had 7–8% protein, 8% sugar and 79% total digestible carbohydrates (mostly starch) and only 2% ash and 8% fiber, equal to conventional grains in apparent nutritional value. Shoots were low in ash and sodium, and compared favorably to alfalfa forage in protein, digestible carbohydrates and energy contents. Mature female stands in the Colorado River delta produced an estimated 1.25 t ha−1 of grain, but over two years in the greenhouse only partial flowering was observed. Nevertheless, D. palmeri appears to be worth developing as a perennial grain and forage crop, especially for salinized, flooded soils. 相似文献
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Temim Deli Mohamed Hbib Ben Atti Rym Zitari-Chatti Khaled Sai Noureddine Chatti 《海洋学报(英文版)》2017,36(12):52-66
The present investigation focuses on population structure analysis of the purple sea urchin Paracentrotus lividus across the African Mediterranean coast, with the main aim of assessing the influence of the Siculo-Tunisian Strait on gene flow disruption in this highly dispersive echinoid species. For this purpose, patterns of morphological and genetic variation were assessed among its populations from the western and eastern Mediterranean coasts. A total of 302 specimens from seven Tunisian sites were collected and examined for morphometric variability at twelve morphometric traits. Concordant results, inferred from CDA (canonical discriminant analyses), pairwise NPMANOVA (non parametric multivariate analysis of variance) comparisons and MDS (multidimensional scaling) plot, unveiled significant inter-population differences in the measured traits among the studied populations. Furthermore, the combined use of the one way ANOSIM (analysis of similarities) and the Discriminant/Hotelling analysis allowed unravelling two morphologically differentiated groups assigned to both western and eastern Mediterranean basins. The SIMPER (similarity percentages) routine analysis showed that total dry weight, test diameter and spine length were major contributors to the morphometric separation between locations and between groups. Pattern of phenotypic divergence discerned in P. lividus across the Siculo-Tunisian Strait is interestingly in congruence with that inferred from the genetic investigation of the purple sea urchin populations from the same region based on the analysis of the mtDNA COI (cytochrome oxidase I) gene in 314 specimens from nineteen locations covering a wider geographic transect, streching westward to the Algerian coast and eastward to the Libyan littoral. The specific haplotypic composition characterizing each Mediterranean basin, as inferred from the minimum spanning network, confirmed the geographic partioning of genetic variation, as revealed by F-statistics and AMOVA (analysis of molecular variance) analyses, yielding significant genetic differentiation between eastern and western Mediterranean populations. The newly detected phylogeographic patterns, observed for the first time in P. lividus throughout the explored distribution range, suggest the involvement of different biotic and abiotic processes in shaping such variation, and provide evidence that a large and geographically exhaustive dataset is necessary to unveil phylogeographic structure within widespread marine species, previously cathegorized as panmictic in part of their distribution range. 相似文献