BEHAVIOR OF RARE EARTH ELEMENTS IN THE SOIL AND VEGETABLE COVER OF URBAN LANDSCAPES IN SOCHI

The geochemical regional specialization of the behavior of rare earth elements (REE) in the soils of Sochi, manifested in the predominance of REE of the middle group, has been established. The enrichment by the middle group of REE is inherited from the rocks (mainly clayey mudstones) of the territory. At the same time, the features of the distribution of REE, characteristic of natural soils, are not violated for soils formed under the conditions of technogenesis. This indicates that the pollution of urban soils is determined by a natural and technogenic factor. The sources of pollution are man-made sites and talus, which lack a soil-vegetation layer, including those recently formed during the preparation for the 2014 Winter Olympic Games and composed of the same material as the parent rocks, but significantly crushed and, accordingly, subject to active weathering. In mosses of the urban zone, in the eluvial landscape, the predominance of the middle group of REE is not observed. However, as we move down the slope, the REE distribution curve relative to the North American shale standardization becomes similar to the similar graph for soils and rocks. The relationship between the accumulation of elements in mosses, and in soils and underlying rocks is revealed when considering the features of fractionation of REE in mosses of the super-aquatic landscape.

Incorporating lakes within the river discontinuum: longitudinal changes in ecological characteristics in stream–lake networks

Lakes and rivers are intimately connected in an alternating series of lentic and lotic reaches in many regions. The study of lakes and their outlets in hierarchical and branching river networks has not gained the attention of stream ecologists, and little effort has been focused on synthesizing the ecology of lake–stream interactions within a drainage network. Rapid and predictable changes in the ecological characteristics of streams occur at the interface with lakes. The influence that a lake might have on a stream is dependent on its position within the stream, stream type and size, lake size and shape, and the inlet and outlet positions. Little is known about the influences of multiple lakes within stream–lake networks and how these influences are determined by network shape and pattern. Fruitful collaborations and novel insights will come from the combined efforts of limnologists, stream ecologists, and landscape ecologists. Geographic information systems and network analyses will play an important role in summarizing aquatic landscape characteristics and creating a predictive science of aquatic networks. Lakes need to be more explicitly incorporated into ecological concepts in stream ecology, and reciprocally, streams need to be incorporated into ecological concepts involving lakes for the successful management and conservation of our aquatic resources.

The evolution of early vertebrate photoreceptors

Meeting the challenge of sampling an ancient aquatic landscape by the early vertebrates was crucial to their survival and would establish a retinal bauplan to be used by all subsequent vertebrate descendents. Image-forming eyes were under tremendous selection pressure and the ability to identify suitable prey and detect potential predators was thought to be one of the major drivers of speciation in the Early Cambrian. Based on the fossil record, we know that hagfishes, lampreys, holocephalans, elasmobranchs and lungfishes occupy critical stages in vertebrate evolution, having remained relatively unchanged over hundreds of millions of years. Now using extant representatives of these ‘living fossils’, we are able to piece together the evolution of vertebrate photoreception. While photoreception in hagfishes appears to be based on light detection and controlling circadian rhythms, rather than image formation, the photoreceptors of lampreys fall into five distinct classes and represent a critical stage in the dichotomy of rods and cones. At least four types of retinal cones sample the visual environment in lampreys mediating photopic (and potentially colour) vision, a sampling strategy retained by lungfishes, some modern teleosts, reptiles and birds. Trichromacy is retained in cartilaginous fishes (at least in batoids and holocephalans), where it is predicted that true scotopic (dim light) vision evolved in the common ancestor of all living gnathostomes. The capacity to discriminate colour and balance the tradeoff between resolution and sensitivity in the early vertebrates was an important driver of eye evolution, where many of the ocular features evolved were retained as vertebrates progressed on to land.