Home – Home – Jornals – Contemporary Problems of Ecology 2016 number 4

This paper is an introduction to the Special Issue of the Journal. Here, a brief historical delineation of the problem of studying interfaces between adjacent ecosystems (ecotones) was done. The high biodiversity of ecotones and their vulnerability to natural and anthropogenic impacts, including invasions of alien species, were noted. It was supposed that there was no contradiction between the ecotone and river continuum concepts. The important ecological role of amphibiotic animals and plants in interactions and functioning of the adjacent ecosystems was emphasized. The problem of studying the quantitative parameters of fluxes of matter and energy between ecosystems in conjunction with their qualitative parameters (the elemental and biochemical composition) was mentioned.

Routs of aquatic allochthonous inputs (aquatic subsidies) to detrital food webs were studied, as well as the aquatic subsidies influence on the formation of the functional and taxonomic structure of soil invertebrate communities in coastal ecosystems. The study took place in the coastal zone of an oxbow lake of the Pra river in the Oksky Reserve. The obtained results indicated the strong dependence of soil animals in the coastal habitats on aquatic subsidies. The isotopic analysis showed that aquatic resources enter soil food webs not only via predators feeding on flying insects or aquatic prey, but also via saprophages decomposing organic debris of aquatic origin. The contribution of water subsidies to the energy balance of soil invertebrates decreased rapidly with the increasing distance from the lake. The fraction of ‘water carbon’ in the tissues of collembolans and saprophages was already negligible at a few meters from the water edge. The dependence of predatory invertebrates on the water resources could be traced at somewhat greater distance (tens of meters).

The substance flow across the water-air boundary on the floodplain lake Kholodnoye (Saratov Oblast) is generally formed by the Culicomorpha (76.1 %) and accounts for 0.35 g/m² of the lake area per year. The energy flow amounts to 1.87 kcal/m², and its most part accounts for the second half of summer and autumn. Annual removal of biogenic elements: 0.18 g/m² for carbon, 0.04 g/m² for nitrogen, 0.004 g/m² for phosphorus. The greatest contribution to flows of substance and energy is brought by large species of midges, as well as phantom midges and medium-sized midges which produce several generations within a year and reach high abundance at a larval stage. Other floodplain lakes of the Volga river with similar biotopical features and species composition of amphibiotic insects are characterized by a quantitatively similar level of exchange processes with adjacent land ecosystems across the water-air boundary.

In this article, the emergence of insects from a floodplain lake of the small Usman river in the Usman forest (Voronezh Oblast) was analyzed. The abundance and frequency of occurrence of 103 species from 7 orders were estimated. Widespread and dominant species and groups ( Chaoborus flavicans (Mg.) (Diрtera), Cloeon inscriрtum (Bgtss.), C. diрterum (L.) (Ephemeroptera) and Scirtes hemisphaericus (L.) (Coleoptera)) were defined. For the vegetative period, the abundance of emerging insects accounted for 1795.5 ± 174.0 ind/m² of the water surface; their biomass amounted to 6756 ± 607.5 mg/m². The extent of the removal of biomass was measured in weight and energy units. Also, the removal of carbon, nitrogen, phosphorus, and essential fatty acids through the emergence of insects to floodplain terrestrial ecosystems was estimated.

Two methods of estimation of the emergence and transfer of biomass of blood-sucking mosquitoes (Diрtera, Culicidae) were compared. It was found that the phenological and quantitative data obtained by the hydrobiological method (using an aquatic net and a dipper) and by using cone-shaped traps were different. Nevertheless, the general characteristics of the studied processes were similar. The results of the hydrobiological method showed that the total value of the annual transfer of biomass by Culicidae accounted for 3.157 g wet weight/m² per year. According to the data obtained by using cone-shaped traps, the total value amounted to 3.457 g wet weight/m² per year.

The taxonomic composition, seasonal dynamics, and emergence intensity of Chironomidae adults that emerged from mountain oligotrophic lake Oiskoe (the Western Sayan, Southern Siberia) were established. The value of annual emergence of chironomid adults averaged 0.42 g wet weight m² in the lake area and approached the value of potential emergence which was calculated based on the estimation of zoobenthos secondary production. For the first time, fatty acid composition and the contents of essential omega-3 polyunsaturated fatty acids (PUFA) were compared between the larvae and adult stages of chironomids. The PUFA content per wet weight unit in adults was more than 7-fold higher as compared to that in larvae. The PUFA flux per lake area unit resulting from the chironomid emergence accounted for 1.752 mg/m x y, that is more than 10 times lower than the global estimation of axport through the amphibiotic insect emergence. Calculations showed that the PUFA flux brought with the chironomid emergence per land unit of the studied mountain territory was very low as compared to that for other landscapes. However, the calculated flux per land unit within the first 15 m of the shoreline was much higher and similar to that in productive landscapes.

Due to long-term monitoring of the abundance and spatial distribution of 18 widespread species of Odonаta, we estimated their contribution to the export of aquatic resources to the Barabinsk forest-steppe ecosystem. Annual emergence of Odonаta varied from 0.8 to 4.9 g/m² of the land area and from 2.3 to 13.3 g/m² of the water area, which is 4-5 times more as compared to that of Diрtera. The general flux of organic matter from water to terrestrial ecosystems remains relatively stable (6-fold interannual variability) irrespective of large interannual variations in the abundance of separate species (e. g., 42-fold interannual variability of Libellula quadrimaculata ). The metal content in 9 Odonаta species was defined. The export of metals provided by odonates decreases in the row K > Na > Mg > Ca > Fe > Zn > Cu > Mn > Pb > Ni > > Cr > Cd. Thus, odonates appeared to be quantitatively and qualitatively important providers of aquatic resources to the forest-steppe landscape of Western Siberia.

The qualitative composition and quantitative characteristics of the syrton allochthonous fraction in one of the rivers of the Russian Far East were examined. It was assumed that the revealed daily dynamics of the terrestrial invertebrates drift was determined by the specifics of their daily migrations on land. A counterargument to the theory of the zoobenthos night drift strategy as a way to avoid drift-feeding predators was suggested.

Beavers act as important agents which regulate the transfer of matter and energy from land to water and vice versa. Nevertheless, despite many examples of regulation of energy and matter flows by beavers, we cannot extrapolate the obtained results and get an overall picture of the beavers’ role as regulators of ecosystem processes. This can be explained by the strong contextual dependency of the results of beavers’ habitat-forming activity and by changes in the animals’ behavior after re-populating the habitat area. The peculiarities of the beavers’ influence on the habitat were analyzed on the example of small rivers which were recently populated by beavers and small rivers where beavers had already been living for 60-80 years.

Microcosm experiments showed that beavers’ vital activity products (BVAP) promoted the increase of nitrogen (N) and phosphorus (P) concentration, the decrease of the N / P ratio in water, the increase of the number and biomass of bacterial plankton. In these conditions, the number and biomass of small-sized Ceriodaphnia dubia Richard and large-sized Daphnia (Ctenodaphnia) magna Straus, which lived separately in microcosms, raised. The cohabitation of these cladocerans in microcosms under the BVAP influence resulted in a more intensive increase in the number and biomass of Daphnia magnа . The similar cohabitation without the BVAP influence led to the predominance of Ceriodaphnia dubia . Bioassay showed that the fertility of Ceriodaphnia dubia decreased in the water which was heavily populated with Daphnia mаgnа under the BVAP influence. It was suggested that the vital activity products of large-sized Daphnia species inhibit the fertility of small-sized Cladocera species. This fact, along with the high competitiveness of large cladoceran species under conditions of a high level of nutrition, determined the forming of the zooplankton communities in beaver ponds, which were characterized by the high number and biomass and the low uniformity.

Fatty acid (FA) contents and compositions in pectoral muscles of 18 species of birds from Novosibirsk, Volgograd, and Yaroslavl oblasts were studied. Three groups of birds that had significantly different FA compositions were distinguished based on multivariate statistical analysis: Passeriformes, Columbiformes, and a group of waterfowl and waterbird species (Charadriiformes, Anseriformes, Podicipediformes, and Ciconiiformes). The highest content of physiologically important docosahexaenoic fatty acid (22:6 n- 3, DHA), which is considered as a marker of aquatic food, was surprisingly found in the biomass of Passeriformes which are terrestrial feeders, rather than in the biomass of waterfowls and waterbirds. It was suggested that Passeriformes species have an ability to synthesize large quantities of DHA from short-chain -3 fatty acids, which is rare among animals.