Daniel A. Zhulidov

Invasion history, distribution, and relative abundances of Dreissena bugensis in the old world: a synthesis of data

We examined trends in expansion patterns and relative abundances of Dreissenabugensis in reservoirs and major river systems in eastern Europe. Based on our own data and data from the literature, it is apparent that trends were variable across river basins and not easily related to environmental conditions. In some cases these did not conform to the patterns typically found for dreissenids. In the early period of expansion beyond its native range in the Dnieper-Bug delta and estuary, D. bugensis rapidly replaced Dreissena polymorpha in the upper Dnieper River system, but increased only gradually and over time became less abundant relative to D. polymorpha in the Don-Manych River system. Contrary to the Dnieper and Don River systems, in the Volga River system considerable spatial variability in relative abundances was apparent, particularly in northern reservoirs. Moreover, even though D. bugensis usually displaces D. polymorpha as the dominant dreissenid, the latter can remain dominant in certain types of habitats where conditions are less favourable for the former. Suggested factors that may be responsible for differences in invasion patterns in the river systems may include differential responses to temperature, or to some other factor(s) associated with geographical latitude, the level of water mineralization, and selective predation by molluscivorous fish. In particular, the northward expansion of D. bugensis seems to be limited by temperature. The lack of long-term data on appropriate scales precludes linking these differences to specific features within the environment, but our comparisons indicate that the expansion of D. bugensis relative to D. polymorpha is more complex than previously believed.

Measurements of Cd, Cu, Pb and Zn in the lower reaches of major Eurasian arctic rivers using trace metal clean techniques

Concentrations of dissolved and particulate Cd, Cu, Pb and Zn were determined in samples collected in summer 1998 from the lower reaches of six major Eurasian arctic rivers: the Onega, Severnaya Dvina, Mezen, Pechora, Ob and Yenisey. These data comprise some of the earliest measurements of trace metals in Eurasian arctic rivers above the estuaries using recognized clean techniques. Significant (alpha = 0.05) differences were observed among mean concentrations of particulate metals in the individual rivers (F < or = 0.006), with highest levels overall observed in the Severnaya Dvina and Yenisey. No significant differences were observed among mean concentrations of dissolved metals in the individual rivers (F = 0.10-0.84). Contributions from anthropogenic sources are suggested by comparison of trace metal ratios in the samples to crustal abundances. These results establish a baseline for assessing future responses of Eurasian arctic river systems to climate-related environmental changes and shifting patterns of pollutant discharge.

Recent trends in relative abundance of two dreissenid species, Dreissena polymorpha and Dreissena bugensis in the Lower Don River system, Russia

We sampled sites in the lower Don River system, Russia between 1977 and 2004 (5 sites) or between 1999 and 2004 (10 sites) to determine relative trends in two dreissenid species, Dreissena bugensis and Dreissena polymorpha. The sites were located in the main river, in connecting reservoirs, and in a major tributary, the Man- ych River. For sites sampled beginning in 1977, D. bugensis was first found in the lower river in 1980 and then more upstream in 1991. The relative proportion of D. bugensis increased to reach a maximum of 30-50% of the dreissenid population by 1999. After 1999, this species decreased at 14 of the 15 sites. At sites in the Don River, the proportion that D. bugensis comprised of the total dreissenid population after 1999 declined from 25-50% to 10-18%, whereas at sites in the Manych River the propor- tion declined from 65-75 % to 33-43 %. The decline of D. bugensis relative to D. polymorpha is unique; in most other water bodies D. bugensis displaces D. poly- morpha over time because of its superior physiological attributes. Reasons for the rela- tive decline of D. bugensis are unclear, but we speculate that selective predation by fish may be a potential factor.

A review of riverine fluxes of hexachlorocyclohexane and DDT to the Azov and Black seas from the former USSR and Russian Federation

Abstract While the Azov and Black seas are subject to anthropogenic pollution to a much higher extent than any other seas, this has been little studied with only a few critical reviews of contaminant fluxes to these seas. Riverine fluxes of the organochlorine pesticides (OCPs) hexachlorocyclohexane (HCH) and DDT to the Azov and Black seas from the former Soviet Union and Russian Federation were thus reviewed for 1986 to 1996. The review was based on official data and data obtained by independent specialists. The amount of HCH used, and the intensity of usage, in these river catchments decreased during the review period. Concurrently, OCP concentrations in the rivers and their fluxes also decreased according to both official and independent data. A comparison of the official and the independent data sets for 1988 revealed significant differences, reflecting the need for more rigorous sampling and analytical protocols for both data sets. According to the OGSNK/GSN data, the flux rates of the five largest rivers were ranked (from largest to smallest) as follows: Don>Dnestr> Danube>Kuban>Dnepro (α-HCH); Danube>Don>Dnestr>Dnepro> Kuban (γ-HCH); Dnestr>Danube>Don>Dnepro-Kuban (DDT+DDE). For rivers with lower annual riverine discharges, the DDT fluxes were surprisingly high (0.43 to 1.49 tonnes a −1). According to independent data for 1988 the rankings of the rivers was: Danube>Don>Dnepro>Dnestr>Kuban (α-HCH); Danube>Don>Dnestr>Dnepro>Kuban (γ-HCH); Danube> Dnepro>Dnestr>Don>Kuban (DDT); Danube>Dnepro>Don>Kuban> Dnestr (DDE). The DDT flux estimates for small rivers derived from independent data were 19 to 46 times lower than those calculated using OGSNK/GSN data. According to the independent data, the total riverine OCP transport from the Russian Federation into the Azov Sea from 1988 to 1996 was 1.288 tonnes of γ-HCH+α-HCH and 1.693 tonnes of DDT+DDE while for the Black Sea they were 3.830 tonnes and 5.116 tonnes for γ-HCH+α-HCH and DDT+DDE, respectively.

Low and Declining Mercury in Arctic Russian Rivers

Mercury (Hg) dynamics in the Arctic is receiving increasing attention, but further understanding is limited by a lack of studies in Russia, which encompasses the majority of the pan-Arctic watershed. This study reports Hg concentrations and trends in burbot (Lota lota) from the Lena and Mezen Rivers in the Russian Arctic, and assesses the extent to which they differ from those found in burbot in arctic rivers elsewhere. Mercury concentrations in burbot in the Lena and Mezen Rivers were found to be generally lower than in 23 other locations, most of which are in the Mackenzie River Basin (Canada). Mercury concentrations in burbot in the Lena and Mezen Rivers also were found to have been declining at an annual rate of 2.3% while they have been increasing in the Mackenzie River Basin at annual rates between 2.2 and 5.1% during roughly the same time period. These contrasting patterns in Hg in burbot across the pan-Arctic may be explained by geographic heterogeneity in controlling processes, including riverine particulate material loads, historically changing atmospheric inputs, postdepositional processes, and climate change impacts.

Biogeography of the Byrranga Mountains, Taymyr Peninsula, Russian Arctic

The Byrranga Mountains (Gory Byrranga) are the most northern mountainous massif of the Taymyr Peninsula (Poluostrov Taymyr) in the Russian Arctic. Although studies of them began in 1736, they are one of the least studied areas of the Arctic. The region has no population, is remote, and has difficult access. As a result, the mountainous tundra ecosystems are preserved practically in a pristine state. The mountains are composed of siltstones and intrusive rocks of neutral composition; vast areas along all the mountain chain are occupied by exposed limestone. Rivers flow in deep intermontane depressions while lakes are found mainly in faults. The climate is an extremely severe continental type. Microclimatic areas provide some relief and support a rich and diverse flora. There have been 391 species and subspecies of vascular plants recorded, but no reliable data on the number of species of mosses and lichens are available. Relict thickets of tall willows are found in protected valleys of piedmont brooks, whereas relict alder-tree thickets occur on warm slopes. The mountain fauna includes nine mammal and 56 bird species. Intermontane depressions serve as corridors for seasonal migrations of wild reindeer that usually spend summers in the southern piedmont areas. Northern piedmonts and wide intermontane depressions are places where herds of musk-ox, introduced in the 1970s, concentrate. The bird fauna of relict willow thickets is highly specific and the fish fauna is quite diverse (16 species), but some species in Taymyr Lake (Ozero Taymyr) have been overexploited. This paper provides the first detailed biogeographical description of the Byrranga Mountains in English.

Temporal and Longitudinal Mercury Trends in Burbot (Lota lota) in the Russian Arctic

Current understanding of mercury (Hg) dynamics in the Arctic is hampered by a lack of data in the Russian Arctic region, which comprises about half of the entire Arctic watershed. This study quantified temporal and longitudinal trends in total mercury (THg) concentrations in burbot (Lota lota) in eight rivers of the Russian Arctic between 1980 and 2001, encompassing an expanse of 118 degrees of longitude. Burbot THg concentrations declined by an average of 2.6% annually across all eight rivers during the study period, decreasing by 39% from 0.171 μg g-1 wet weight (w.w.) in 1980 to 0.104 μg g-1 w.w. in 2001. THg concentrations in burbot also declined by an average of 1.8% per 10° of longitude from west to east across the study area between 1988 and 2001. These results, in combination with those of previous studies, suggest that Hg trends in Arctic freshwater fishes before 2001 were spatially and temporally heterogeneous, as those in the North American Arctic were mostly increasing while those in the Russian Arctic were mostly decreasing. It is suggested that Hg trends in Arctic animals may be influenced by both depositional and postdepositional processes.