Zoobenthic communities of the Dagestan Region of the Caspian Sea

The results of bottom community studies of the Dagestan Region of the Caspian Sea were presented; key factors affecting their formation were distinguished. Special attention was paid to restoration of the amphipod Pontogammarus maeoticus, which was characteristic in the coastal zone community until it was destroyed after a rise in the sea-level. It was established that biomass of the benthos was much higher in the period of the rise in the sea level than in the years of a low sea level.Original Russian Text Copyright © 2005 by Biologiya Morya, Guseinov.     

Impact of silkmoth outbreak on taiga wildfires

We provide a quantitative analysis of postoutbreak wildfire frequency within the confluence of the Yenisei and Angara rivers affected by the Siberian Silkmoth (Dendrolimus sibiricus Tschetv.). A catastrophic outbreak was observed in 1993–1996. It expanded to about 1 million ha and caused stand mortality on an area of about 460000 ha. For the outbreak area, the fire frequency was about 7 times higher when compared to the reference area; on the burned area, it was 20 times higher. The peak of fire activity within outbreak areas occurs in May–June, while that for undamaged coniferous stands is in July. The number of fires is correlated with the mean monthly air temperature (r = 0.65) of June. The area of fires displays a negative correlation with moisture conditions: precipitation (r =–0.53), drought index (SPEI: r =–0.57), and ground-cover moisture content (r =–0.57). Extensive fires prevail within outbreak areas (S > 1000 ha), while within the control there is a smaller area of fires. Multiple (reoccurring) wildfires are typical for pest outbreak areas. The area of these fires is related to their reoccurrence by logarithmic dependence (17% of the territory twice burned by forests fires, 5% on that burned three times, and 0.5% on that burned four times). Wildfires in the outbreak areas surpress the initial forest recovery by destroying the regeneration of conifers: 20 years after the outbreak, >90% of disturbed areas are occupied by grass–bush and small-leaved cenoses.     

Impact of iceberg scouring on macrobenthic communities in the high-Antarctic Weddell Sea

UW-video guided multibox corer sampling in- and outside iceberg scours provided quantitative macrozoobenthos samples for analyses of effects of grounding icebergs on infaunal benthic communities. These studies were performed on the southeastern Weddell Sea shelf off Kapp Norvegia and Austasen. Based on the UW-video sequences, stations were grouped a priori into two different "disturbance categories" and into undisturbed areas.Average biomass of major taxa in the cores of undisturbed areas was significantly higher (14,716.5 g wet weight m^-2) than in old (405.3 g w. wt. m^-2) or in young scour marks (9.2 g w. wt. m^-2). The habitat taxon richness, too, was highest in undisturbed areas (on average, 11.8 taxonomic units occurred per core), decreased in old scour marks (9.0) and was lowest in young scours (6.8). In undisturbed areas, a higher developed community structure was reflected by a greater variety of taxonomic groups, some of which were principally absent in scours.In young scours, the number of taxa was significantly reduced. Motile forms such as echinoderms and crustaceans, mainly amphipods, and juvenile polychaetes, in particular pioneering species of the family Spionidae, started the recolonization of the devastated areas. Burrowing organisms occurred in older scours where the initially overcompacted sediment had softened. In the course of the re-establishment of macrofaunal communities (after some years/decades), the faunal composition is expected to change towards a "normal" dominance of suspension-feeding organisms, mainly sponges and bryozoans, being typical for wide areas on the southeastern Weddell Sea shelf.A more detailed taxonomical approach, using 167 polychaete species as representatives of the macrozoobenthos, also revealed significant differences between undisturbed and affected areas. The mean abundances (784, 389, and 242 ind. m^-2, respectively), as well as habitat species richness (11.6, 5.5, and 3.1, respectively), decreased from undisturbed areas to old to young iceberg scours. Similarly, a large variety of motile and sessile forms was encountered among the polychaetes at undisturbed sites, whereas in scours, the polychaete fauna was impoverished in terms of species richness, abundance and variety of feeding types and lifestyles.     

Study of petroleum-degrading activity of microflora from the shoreline region of the Caspian Sea

Soil samples from the shore of Baku Bay (Caspian Sea), were studied. The content of oil products in the samples amounted to 2.7-8.0 wt%. The total counts of microorganisms were 1.8 x 10(6) cells per g soil, which is by two orders of magnitude lower compared to soils free from oil pollution. In addition, the diversity of microflora is considerably narrower. The samples were used to isolate pure cultures of microbial degraders capable of assimilating 24 to 32% of the oil introduced into liquid nutrient medium in six days. It was demonstrated that the fraction composition of residual oil changed and both light and heavy oil fractions were degraded.     

High resilience of Mediterranean land snail communities to wildfires

In the Mediterranean region, wildfires have devastating effects on animals with limited mobility. With their poor dispersal abilities, their habitats on vegetation and in litter, and their sensitivity to humidity and shade, we expected land snails to be an interesting model to assess short, medium and long-term impact of fires on fauna biodiversity and their resilience. Stratified sampling was carried out on 12 sampling sites in garrigues and forests of Provence (southeastern France), according to fire regime (number of fires, fire intervals and age of the last fire) over the past 30 years. Data were investigated using diversity indexes, Kruskal–Wallis test, dendrogram of affinities and Correspondence Analysis (CA). We found, however, that Mediterranean land snail communities are particularly resilient to fires. Although abundance is drastically reduced in the short-term, species richness and community diversity are preserved provided that the time lapse between two successive fires is longer than the time required for recovery (i.e. around 5 years). This high community resilience in the short-term may be partly due to ecological and ethological aptitudes of land snails. However, these astonishing results, which have implications for conservation biology, are mainly due to the presence, within burned areas, of cryptic refuges that allow initial land snail survival, malacofauna persistence after successive fires and consistent biogeographical patterns in the long-term.     

History of aquatic invertebrate invasions in the Caspian Sea

Incorporation of the fossil record and molecular markers into studies of biological invasions provides new historical perspectives on the incidence of natural and human-mediated invasions of nonindigenous species (NIS). Palaeontological, phylogeographic, and molecular evidence suggests that the natural, multiple colonizations of the Caspian basin via transient connections with the Black Sea and other basins played an important role in shaping the diversity of Caspian fauna. Geographically isolated, conspecific Ponto-Caspian lineages that currently inhabit fragmented habitats in the Ponto-Caspian region show limited genetic divergence, implying geologically recent episodes of gene flow between populations during the Pliocene to Pleistocene. Several molluscan lineages in the Caspian Sea may have descended from Lake Pannon stock before the Late Miocene isolation of the Caspian depression, about 5.8 million years ago. Anthropogenic activities during the 20th century were responsible for a 1800-fold increase in the rate of establishment of new aquatic species in the Caspian Sea compared to the preceding two million years of natural colonization. The observed success of NIS invasions during the 20th century was due primarily to human-mediated transport mechanisms, which were dominated by shipping activities (44%). Human-mediated species transfer has been strongly asymmetrical, toward the Volga Delta and Caspian Sea from or through Black and Azov Seas. Global and regional trade, particularly that mediated by commercial ships, provides dispersal opportunities for nonindigenous invertebrates, indicating that future invasions in the Caspian Sea are anticipated.     

Phytoplankton distribution in the Caspian Sea during March 2001

Phytoplankton abundance, biomass and species composition of the Caspian Sea were evaluated by using samples collected from the Iranian (southern Caspian Sea) and southern Kazakhstan (eastern Caspian Sea) surface waters in March 2001. A total of 45 taxa were found in the samples (20 diatoms, 17 dinoflagellates and 8 others). Abundance and biomass of diatoms were high at the eastern stations, while dinoflagellates were dominant in terms of both biomass and abundance in the southern region. Average abundance and biomass were 40 000 ± 35 000 cell l⁻¹ and 580 ± 690 μg l⁻¹. The mean biomass value found here for the Middle and southern Caspian Sea in March are difficult to compare with the past due to limited information, but seems higher than previously registered values. Higher chlorophyll values were also apparent from the SeaWIFS images in 2001 compared to those in 1998. This is suggested to be due to decreased grazing of phytoplankton by zooplankton which is voraciously preyed by the recent invasive ctenophore Mnemiopsis leidyi.     

Sturgeon abundance and distribution in the Caspian Sea.

The number of sturgeons and their distribution on feeding grounds in the Caspian Sea were assessed. Data were collected between 1991 and 1996 on environmental factors, species composition, and population sizes in the Northern, Middle and Southern Caspian Sea except for Iranian waters. The results show a drastic decline of the sturgeon populations on the feeding grounds at sea. In order to preserve the Caspian Sea sturgeon populations, efforts of all States surrounding the Caspian Sea must be increased and harmonised to serve a single system of fishery management, stock conservation and enhancement measures based on natural reproduction and artificial propagation.     

Climate-dependent changes in herbaceous vegetation on solonchakous solonetzes of the Northern Caspian Lowland

A steady and significant warming of the autumn-winter period and an increase in moisture supply during the growing season have taken place in the Northern Caspian Lowland, resulting in its general mesophytization. In particular, the dominant species in plant communities on solonchakous solonetzes have changed, with black wormwood (Artemisia pauciflora) being replaced by forage kochia (Kochia prostrata). However, these ecosystems remain in dynamic equilibrium, and their current changes and productivity fluctuations do not exceed natural limits and are reversible.     

Spatial-typological structure of bird communities in coniferous and deciduous forests of the Northern Volga region

Based on materials collected during continuous year-round strip censuses, the spatial heterogeneity of bird communities in coniferous and deciduous forests of the Northern Volga region was analyzed for the first time and the key factors determining it were identified. A spatial-temporal classification of bird communities of the study area was made, and a quantitative estimate of the strength and generality of the relationship between the spatial heterogeneity of bird communities and environmental factors is given. The spatial-temporal structure of bird communities is mainly determined by forest cover, seasonal variation in heat supply, tree species composition, build-up area, and relief.     

Elements of nitrogen cycle in landscapes of the Northern Caspian Lowland

The input of zoogenic nitrogen to desert-type biocenoses is generally lower than the input of nitrogen with plant necromass (1.7 g N/m²), but zoogenic nitrogen is distributed extremely unevenly, and its input at sites near burrow openings, where animal excrements accumulate (about 1% of the total area), reaches 75 g N/m²; i.e., is 17 times higher. Zoogenic nitrogen coming with solid and liquid excreta has little effect on the mineral nitrogen content of soils in ground squirrel colonies during the dry period.     

Formation of Forest Biogeocenoses on Disturbed Lands of the Northern Caspian Region

Biology Bulletin - Abstract—The features, trends, and rates of formation of new forest biogeocenoses on anthropogenically disturbed lands, in particular, on an unused pond created on heavy...     

Ecosystem of Caspian Sea threatened by pet-traded non-indigenous crayfish

Freshwater ecosystems are particularly vulnerable to biological invasions; the aquatic animal pet trade has been recognized as a significant pathway of introductions. Crayfish are considered a model group of traded organisms with a series of highly successful species already established in the wild, having the potential to negatively influence both indigenous crayfish species (ICS) as well as alter occupied ecosystems. Eastern Europe includes the entire native ranges of indigenous Astacus leptodactylus sensu lato and A. pachypus. This region has been largely overlooked and considered relatively safe from the adverse impacts of non-indigenous crayfish species (NICS). In this study, we evaluated the crayfish pet trade in the Lower Volga Region with special emphasis on Astrakhan, the biggest city of Russian Federation in the region located just in the delta of Volga River, thus being a potential gateway of introductions to the Caspian Sea and adjacent freshwaters. The local pet trade involves 12 NICS. Considering their origin, availability, probability of establishment, invasiveness and further aspects, Procambarus fallax f. virginalis, P. clarkii and Cherax destructor are considered potentially the most problematic, including transmission of diseases like crayfish plague caused by Aphanomyces astaci or white spot syndrome virus. Taking this information as a whole, the availability of NICS with a high probability of overlapping the entire range of European ICS means that attention is warranted. Further research is needed to corroborate the abilities of NICS and their associated diseases to withstand specific conditions of the Caspian Sea as well as the adjacent Black and Azov Seas, all possessing different degrees of elevated salinity.     

Spatial structure of soil macrofauna in the Northern Caspian clay semidesert

Long-term soil-zoological studies have been performed in the Northern Caspian clay semidesert, at the Dzhanybek station of the Institute of Forest Science, Russian Academy of Sciences. Their results are summed up, and specific features of the spatial distribution of invertebrates (macrofauna) in soils constituting a three-component solonetz complex are discussed.     

Microbiological studies in the deepwater area of the Southern Caspian Sea

For the first time, microbiological monitoring was performed in the deepwater area of the Southern Caspian Sea. It revealed seasonal and interannual variations in total microbial content and concentrations of saprophytes and other physiological groups of bacteria in water and bottom sediments. The biomass, generation time, and bacterial production were determined. The most profound variations in microbial content, biomass, and production were found to occur in the water column and in bottom sediments at depths to 200–250 m.     

Climate changes and virgin vegetation dynamics in the Northern Caspian lowland

A wavy trend toward increasing vegetation biomass in desert, semidesert, and steppe communities growing on solonetzic soils was discovered in the Northern Caspian region over a 60-year observation period (1952–2013). The trend is caused by warming during winter months (due to redistribution of soil moisture) and the improvement of hydrothermal conditions in spring months (the period of most active plant vegetation).     

Microbiological studies in the deepwater area of the Southern Caspian Sea

For the first time, microbiological monitoring was performed in the deepwater area of the Southern Caspian Sea. It revealed seasonal and interannual variations in total microbial content and concentrations of saprophytes and other physiological groups of bacteria in water and bottom sediments. The biomass, generation time, and bacterial production were determined. The most profound variations in microbial content, biomass, and production were found to occur in the water column and in bottom sediments at depths to 200-250 m.