Distribution and status of Posidonia oceanica meadows on the North-Western coast of Algeria

Posidonia oceanica is an endemic species of the Mediterranean Sea that in pristine coastal waters forms extensive meadows, which are, actually, exposed to natural and anthropogenic pressures, causing their regression throughout the basin. The aim of our study is to summarise and evaluate current knowledge about the characterisation of Posidonia oceanica along the Western Algerian coast, in order to provide new evidence about the distribution and health status this species. To realize our objectives, we combined extracted data from published articles, theses, results of project reports, in situ observations and laboratory analysis. The results show the presence of the meadows in fifteen coastal zones of Western Algeria, mainly located in shallow surface waters from 0.5 to 18 metres depth.The mean leaf length across all sites ranged from 153 to 667 mm. The mean number of leaves/shoot ranged between 4.7 ± 0.9 and 6.0 ± 0.5 leaves/shoot. Leaf length showed a highly significant difference between the cold and hot season. The data analysis shows that the leaf biometric values and the shoot densities of the P. oceanica are greater than those of Mediterranean samples although these measures tend to decrease deeply. The analyses carried out on structural features of P. oceanica show that the Western Algerian meadows are, globally, in good health status according to standardised scale. The available data on P. oceanica summarised in this article represent an important starting point to build effective plans for understanding levels of environmental threats and for supporting conservation strategies for these important ecosystems. Conversely, the limited information available on this seagrass along the Western Algerian costs only allows the description of some structural features, and permits us to draw overall conclusions on its general health status

Additional new records of Caulerpa cylindracea Sonder 1845 along the West Algerian Coasts

Since considered as invasive species, Caulerpa cylindracea Sonder 1845 has been the subject of numerous prospecting works aiming its localisation and identification along the western Mediterranean Coasts. In this study, we provide new occurrence of the introduced seaweed Caulerpa cylindracea in the West Algerian coasts. C. cylindracea has been reported for the first time in Canastel and Zimba (West Algerian coasts) at different density distribution levels. The colonisation level was estimated to Level (I) for Zimba, Canastel and Marsat El Hadjaj sites, which indicated a beginning of spreading. By contrast, in Cap Carbon a Level (II) was recorded suggesting an advanced colonisation of the invasive taxon. Macroalgae and seagrass assemblage characterisation showed low cover for all species in the invasion zone. Accordingly, Caulerpa cylindracea is more present in Cap Carbon than in Zimba, Canastel and Marsat El Hadjaj. Considering the observed abundance of macroalgae and seagrasses, Caulerpa prolifera seemed to resist the invasion of C. cylindracea in Marsat El Hadjaj

Additional new records of Caulerpa cylindracea Sonder 1845 along the West Algerian Coasts

122-129Since considered as invasive species, Caulerpa cylindracea Sonder 1845 has been the subject of numerous prospecting works aiming its localisation and identification along the western Mediterranean Coasts. In this study, we provide new occurrence of the introduced seaweed Caulerpa cylindracea in the West Algerian coasts. C. cylindracea has been reported for the first time in Canastel and Zimba (West Algerian coasts) at different density distribution levels. The colonisation level was estimated to Level (I) for Zimba, Canastel and Marsat El Hadjaj sites, which indicated a beginning of spreading. By contrast, in Cap Carbon a Level (II) was recorded suggesting an advanced colonisation of the invasive taxon. Macroalgae and seagrass assemblage characterisation showed low cover for all species in the invasion zone. Accordingly, Caulerpa cylindracea is more present in Cap Carbon than in Zimba, Canastel and Marsat El Hadjaj. Considering the observed abundance of macroalgae and seagrasses, Caulerpa prolifera seemed to resist the invasion of C. cylindracea in Marsat El Hadjaj

Bioclimatic analysis in a region of southern Italy (Calabria)

In this study, an analysis of precipitation and temperature data has been performed over 67 series observed in a region of southern Italy (Calabria). At first, to detect possible trends in the time series, an analysis was performed with the Mann–Kendall non-parametric test applied at monthly and seasonal scale. An additional investigation, useful for checking the climate change effects on vegetation, has also been included analysing bioclimatic indicators. In particular, Emberger, Rivas-Martinez and De Martonne indices were calculated by using monthly temperature and precipitation data in the period 1916–2010. The spatial pattern of the indices has been evaluated and, in order to link the vegetation and the indices,different indices maps have been intersected with the land cover data, given by the Corine Land Cover map. Moreover, the temporal evolution of the indices and of the vegetation has been analysed. Results suggest that climate change may be responsible for the forest cover change, but, given also the good relationship between the various types of bioclimate and forest formations, human activities must be considered

Evidence of Life on Mars?

Evidence is reviewed which supports the hypothesis that prokaryotes and eukaryotes may have colonized Mars. One source of Martian life, is Earth. A variety of species remain viable after long term exposure to the radiation intense environment of space, and may survive ejection from Earth following meteor strikes, ejection from the stratosphere and mesosphere via solar winds, and sterilization of Mars-bound spacecraft; whereas simulations studies have shown that prokaryotes, fungi and lichens survive in simulated Martian environments--findings which support the hypothesis life may have been repeatedly transferred from Earth to Mars. Four independent investigators have reported what appears to be fungi and lichens on the Martian surface, whereas a fifth investigator reported what may be cyanobacteria. In another study, a statistically significant majority of 70 experts, after examining Martian specimens photographed by NASA, identified and agreed fungi, basidiomycota (“puffballs”), and lichens may have colonized Mars. Fifteen specimens resembling and identified as "puffballs" were photographed emerging from the ground over a three day period. It is possible these latter specimens are hematite and what appears to be “growth” is due to a strong wind which uncovered these specimens--an explanation which cannot account for before and after photos of what appears to be masses of fungi growing atop and within the Mars rovers. Terrestrial hematite is in part fashioned and cemented together by prokaryotes and fungi, and thus Martian hematite may also be evidence of biology. Three independent research teams have identified sediments on Mars resembling stromatolites and outcroppings having micro meso and macro characteristics typical of terrestrial microbialites constructed by cyanobacteria. Quantitative morphological analysis determined these latter specimens are statistically and physically similar to terrestrial stromatolites. Reports of water, biological residue discovered in Martian meteor ALH84001, the seasonal waning and waxing of atmospheric and ground level Martian methane which on Earth is 90% due to biology and plant growth and decay, and results from the 1976 Mars Viking Labeled Release Experiments indicating biological activity, also support the hypothesis that Mars was, and is, a living planet. Nevertheless, much of the evidence remains circumstantial and unverified, and the possibility of life on Mars remains an open question. (4) (PDF) Evidence of Life on Mars?. Available from: https://www.researchgate.net/publication/331792376_Evidence_of_Life_on_Mars [accessed Jul 05 2020]

Structures/textures of living/fossil microbialites and their implications in biogenicity. An astrobiological point of view

Atacama’s microbialites, able to live in such extreme environment, are possible candidates as models for searching life in other planets or moons. At present, little is known about their microstructure and composition. This study analyzes, mainly, the terrestrial microstructures in a dimensional field longer than 0.1 mm, through an original approach using photographs and macro pictures, appropriately magnified and consequently little defocused, in comparison with analogous images shot by NASA Rovers on Martian outcroppings. A method able to permit comparison of structures and textures of terrestrial microbialites to the microscopic photo images (MI) shot by the cameras mounted on the NASA rovers that since more ten years are present on the Red Planet (Opportunity, Spirit, Curiosity). The study highlights occurrence of widespread structures likes microspherules (or clots), often organized into some higher order settings, such are donuts, polispherules, filaments and, above all, intertwined filaments of microspherules, all showing features of an imperfect geometrical repetitiveness. The structural analysis has been connected with a textural study by a multifractal analysis, that is able to distinguish terrestrial biogenic stromatolites from abiogenic pseudo-stromatolites, and giving us a tool that might be applied for astrobiological purposes