The recent sedimentation history of Aqualate Mere (Central England): assessing the potential for lake restoration.

As part of English Nature's Lakes Flagship Project to address adverse environmental impacts on selected, important lakes, a proposal has been made to dredge Aqualate Mere. The site has experienced rapid, 'recent' sedimentation thought to be derived from a nearby canal. The aim of this study has been to determine the recent sedimentation history of the site in order to assess the possibility of the disposal to land of its sediments and the efficacy of this form of lake restoration. A predominantly clayey silt layer was found across the lake beneath which darker, organic-rich sediments were noted. This transition may represent the input of canal-derived sediments, although it may reflect other environmental changes at this time. The radiometric dating technique employed was unable to date this sediment boundary. A further change in the characteristics of the upper part of the clayey silt layer may represent an additional influence of the canal. Heavy metal levels were modest, whereas nutrient levels were relatively high and some pesticides were detected. Topsoil erosion supplying nutrients and other compounds associated with agriculture have been an important source of the lower layers of the clayey silt sediments in particular. The highest levels of most pollutants were found in the finer sediments in the uppermost (post-1950s) part of the sediment profile. These sediments appear to reflect a change in the characteristics of the sediments of the canal, which was associated with a change in the nature of its water supply. The key geochemical properties of the sediments should not preclude the land-based disposal of dredged materials under current UK regulations for waste management. Accurate estimation of sediment quantities was limited, as the interface between the 'recent' and underlying sediments was not positively identified at all sample points

Crustacea decapoda da praia rochosa da Ilha do Farol, Matinhos, Paraná: II. Distribuição espacial de densidade das populações

<abstract language="eng">Decapod crustaceans from rocky shore at Farol Isle, Matinhos, Paraná, Brazil. II. Spatial distribution of population densities. A study of the spatial distribution of the decapod populations from a rocky shore at Farol Isle, Matinhos, State of Paraná, Brazil (25º51'S, 48º32'W) was canied out. In the supralittoral the rocky surface is covered partially by a layer of litter coming from the terrestrial habitats; in the midlittoral boulders and pebbles cover the rocky basin and in the infralittoral, there is a belt of seaweeds. A total of 8 samples were taken by hand, two from each of the following levels: supralittoral (emersion time 8-12 hours), upper midlittoral (4-8), lower midlittoral (0-4) and limit between midlittoral and infralittoral, monthly, from May/1990 to April/1991. The number of species increased from supralittoral (5) to infralittoral (22) and a clear vertical zonation on density was observed according to the emersion time gradient. The supralittoral is characterized by grapsids Armases angustipes (Dana, (1852), Cyclograpsus integer H. Milne Edwards, 1837 and Metasesarma rubripes (Rathbun, 1897) which have terrestrial habits and aerial respiration as a main way in obtaining the oxygen. In the midlittoral, the decapods show three basic types of adaptation against emersion desiccation and thermal stresses: (1) by digging into wet mud among the stones such as Panopeus americanus Saussure, 1857, Panopeus occidentalis Saussure, 1857 and Eurypanopeus abbreviatus Stimpson, 1860, (2) by resting in shady and wet space between the boulders and pebbles or underside of them, like Pachygrapsus transversus (Gibbes, 1850), Petrolisthes armatus (Gibbes, 1850) and adults of Menippe nodifrons Stimpson, 1859 and (3) by clinging over the soaked filamentous algae layer on the pebbles or bouders surfaces, a strategy observed in small species such as Pilumnus dasypodus Kingsley, 1879, Podochela sp., Petrolisthes galathinus (Bosc, 1801 ), Alpheus bouvieri A. Milne Edwards, 1878 and juveniles of Menippe nodifrons. In the infralittoral, small species which are vulnerable to desiccation stresses share space by diversification of their diet and adaptation strategies such as camouflage, body color change according to the substratum, flattened body for tight adhesion on hard surface and rapid movements. The main species of this zone are Petrolisthes armatus, Petrolisthes galathinus, juveniles of Menippe nodifrons, Epialtus brasiliensis Dana, 1852, P. dasypodus, Synalpheus fritzmuelleri Coutière, 1909, Megalobrachium roseum (Rathbun, 1900) and species of Palaemonidae. The rocky shore at Farol Isle is a complex architectural environment due to the conjunction of diversified habitats such as litter over a hard surface, spaces and crevices among boulders and pebbles, muddy substratum and phytal

Квитанция по принятию объявление в газету "Вечернее Тбилиси"

Русудан Багратион-Мухранская - дочка Нико Бур