The first data on the content of pico-sized detrital particles (0.2–2.0 μm) are obtained by epifluorescence microscopy in
the upper Volga reservoirs. The spatial and temporal distributions of density and mass of picodetritus are described. The
quantitative proportions between heterotrophic bacteria, picophytoplankton, and pico-sized detritus were revealed.
Key wordspico-sized detrital particles-autotrophic picoplankton-heterotrophic bacteria-the upper Volga reservoirs
The changes in population of Baikal amphipod Pallasea cancellus (Pallas) from four remote local populations is described by comparing 21 morphological features. The population changes of
individuals of different sexes, which allows the geographical variability of sexual dimorphism to be found, is shown. The
morphological differences between crustaceans inhabiting different parts of Lake Baikal and the Angara River were estimated
more precisely by analyzing the principal components. The junction between northwestern and southeastern population groups
(which may be considered geographical allopatric races) was found.
This experimental study examines the influence that acyclic stepwise temperature regimes with 4.4 and 8.8°C increments in
a range of 14.8 to 25.5°C have on the dynamics of the number of Simocephalus vetulus (O.F. Müller). It is revealed that an increase in the number of this dominant species of littoral zooplankton may be stimulated
by differently directed acyclic stepwise changes in temperature. However, the maximal development of the population is registered
after a decrease in water temperature from 24.3 ± 0.7 to 20.4 ± 0.5°C and from 19.9 ± 0.8 to 15.5 ± 0.4°C. Under the same
temperature conditions, a prolonged stimulating effect is observed. Our results confirm the assumption put forward earlier
that, in order to define the real ecological optimum for a species by a specific environmental factor, it is necessary to
consider not only the limits of the optimal values of the factor, but also the dynamics of their changes and the possibility
of after-effects of the factor (prolonged and delayed effects).
KeywordsCladocera–
Simocephalus vetulus
–dynamics of number–prolonged stimulating effect–delayed effect–stepwise impacts–temperature
Experimental studies on the abundance dynamics and thermal tolerance of cladoceran Ceriodaphnia quadrangula (O.F. Müller, 1785) as they depend on the value and action pattern of a thermal factor, as well as field observations and
mathematical calculations were carried out. Based upon the results of these studies, the values of the temperature zone of
normal vital functions (17.0–25.0°C) and of the zones of temperature “static” optimum (21.4–25.0°C) were determined for C. quadrangula. It was shown using experimental populations of C. quadrangula as an example that it is necessary not only to keep the range of the factor optimal values within the tolerance scale (i.e.,
the static optimum) but also to maintain the optimal parameters of dynamic factor changes (or “dynamic optimum”) in order
to form optimal conditions for their growth and development. For C. quadrangula this dynamic temperature optimum is 24.0 ± 1.1°C, with non-periodical (graded) warming to 24.7–25.3°C over five to eight
days.
More than twenty helminth species have been found for the juvenile starry flounder inhabiting the Ukhtolok River on the coast
of western Kamchatka. Most of the species have been registered for the first time. Pictures and a morphological description
of monogeneans of Gyrodactylus genus (G. flesi, G. cf. robustus and Gyrodactylus sp.) and nematode larvae (Acuariidae gen. sp.), as well as a brief ecological analysis of the parasitic invasion of the studied
fish, are presented.
Key wordsPlatichthys stellatus-Kamchatka-helmintes-
Gyrodactylus
-Acuariidae
Metacercariae of two species of trematodes from the fam. Diplostomidae from the cranial cavity of the African catfish Clarias gariepinus are described. The metacercaria Tylodelphys grandis n. sp. is described for the first time. Data are presented on the infection rate of catfishes in Lake Tana.
Key words
Dolichorchis tregenna
-
Tylodephys grandis
-
Clarias gariepinus
-Trematoda-Diplostomidae-description-Ethiopia
A heavy parasitic load from trematode partenites of Apophallus muehlingi (Jagerskiold, 1898) was observed in the mollusk population of Lithoglyphus naticoides (Pfeiffer) after its natural invasion into the Rybinsk Reservoir. An elevated concentration of glycogen was detected in the
muscles of infected fish, both in the natural populations and under experimental conditions. Interspecific differences were
found for the protein concentrations when elevated concentrations were observed in the muscles of the infected roach, and
no differences were discovered for the goldfish (both infected and parasite-free). The ties between the biochemical parameters
and motor activity are discussed for the infected fish.
Keywordstapeworms–Trematoda–fish–mollusks–glycogen–proteins
The morphology of the reproductive system at different stages of ontogenesis and ultrastructural peculiarities of the copulatory
organs and uterine in Monocercus arionis (Sibold, 1850) Villot, 1982 (Cyclophyllidea) have been studied. The muscle of the outer wall of the cirrus bag has a higher
organizational level than typical smooth-muscle cells in cestodes. The cirrus is armed with typical filamentous and bladelike
microtriches. The uterine epithelium contacts the thin capsule of the developing embryos located closely to the uterus wall,
and the embryos contact each other in the uterine cavity in what can be interpreted as placental interactions. The specificity
of the structure and arming of the copulatory apparatus has been considered, and the ultrastructural peculiarities of the
uterus in the members of different orders of cestodes have been compared and analyzed.
KeywordsCestoda–reproductive system–morphology–ultrastructure
The polychaetes Streblospio benedicti (Webster, 1879) and Manayunkia aestuarina (Bourne, 1883) have been recorded in the Vistula Lagoon of the Baltic Sea since the mid 1990s. The impact that salinity and
the necrozooplankton (dead plankton) concentration in the near-bottom layer have on their distributional patterns was studied.
The spatial distribution of these polychaetes depends on the water salinity; however, no correlation was found between their
abundance and the necrozooplankton concentration. An area of high necrozooplankton concentration was defined for the near-bottom
water layer in the central part of the lagoon; its position is mostly determined by the currents. We assume that the sustainable
presence of S. benedicti and M. aestuarina is supported by their opportunistic species biology patterns and the lagoon hydrology, even in the last decade of unfavorable
water mineralization conditions.
Dynamics of the size-age structure and sexual structure of the population and characteristics of reproduction and life cycle
have been studied in the Baikal invader Gmelinoiudes fasciatus (Stebbing, 1899) in Lake Ladoga. The studied characteristics display both similar features with and differences from populations
of this species in other waterbodies. It is found that the size and age structure of the G. fasciatus population changes in the circannian aspect under the influence of complex of environmental factors. The sexual structure
of the population is dynamic, but a sex ratio of approximately 1: 1 is maintained in the circannian cycle. Six principal periods
of hatching are recognized. The main factor determining the timing of the start and termination of the reproduction period
in G. fasciatus is temperature. The weight of eggs oviposited by the female over the whole life cycle (about 21.5 cal in the energy equivalent)
amounts to about 60% of the female body weight.
KeywordsLake Ladoga–
Gmelinoides fasciatus
–size and age structure–sexual structure–reproduction–life cycle–abundance–biomass
The rotifer Kellicottia bostoniensis (Rousselet, 1908), which is common in North American water-bodies, has been recorded in 13 different lakes of the European
part of Russia. A morphometric analysis has been made of populations from 7 lakes. The assumption has been made that the size
of the spines of K. bostoniensis in small waterbodies depends on the presence of predators. Depth-related changes in density and viscosity in deep lakes with
temperature stratification can also influence this feature.
Keywords
Kellicottia bostoniensis
–new locations–morphological variability–spatial distribution–waterbodies of European Russia
Larva of the water mite Tiphys pistillifer (Koenike) is described for the first time. The morphology of this species is analyzed and male and female of the adult stage
are re-described. Keys to females and males of the subgenus Acercopsis are provided.
Studies of the bottom fauna of the Selenga River have identified a rare species of free-living nematodes Eudorylaimus lotharingiae Altherr, 1963. An illustrated description of females and an unknown male of this species is presented. Morphologically, E. lotharingiae is close to the Baikal species E. spongiophylus Batalova, 1963, but it differs in the lateral annulation of its subcuticular layer, wider lip region, shorter odontostyle,
and longer prerectum.
Keywordsfree-living nematodes-Selenga River-rare species-
Eudorylaimus lotharingiae
The ultrastructure of the marine predatory flagellate Metromonas simplex Larsen et Patterson was studied. The cell is surrounded by a low-contrast fibrous layer composed of thin hairs covered by
a thin bilayer membrane and an outer layer of thin short fibers. The plasmalemma lies under these layers. The predator captures
whole cells of the prey, usually bodonids or chrysomonads. The cytostome as a cell pocket is undetectable. The long flagellum
bears very thin mastigonemes (hairs) with lengths of 0.8–1.0 μm; the short flagellum is naked and reduced in length. The transitional
zone lacks spirals or other additional elements. The transversal plate is elevated on the cell surface. The flagellar root
system is very simple and has one microtubular band which originates near the kinetosomes. The latter are parallel to each
other and interconnected by fibrous bridges. The vesicular nucleus, Golgi apparatus, and endoplasmic reticulum are of typical
structures. The oval mitochondria of 0.6–2.5 μm contain lamellar cristae. The cylindrical extrusomes (trichocysts) found in
the cytoplasm have lengths of 1.0–1.4 μm and diameters of 0.12–0.08 μm. The trichocysts have a wheel-shaped structure with
13 spokes visible in cross-sections. The contractile vacuole is absent. The similarity that M. simplex shares with Metopion fluens Larsen et Patterson, cryothecomonads, and other predatory flagellates is discussed.
Keywords
Metromonas simplex
–ultrastructure–predation–cryomonadids
The ultrathin structure of amoeboid flagellate Thaumatomastix sp. is considered. The cell is surrounded by two-layered triangular scales. They are formed on the surface of mitochondria.
Pseudopodia grabbing bacteria run from ventricular furrow, which is armored with two longitudinal bands of microtubules. Heterodynamic
flagella run from small flagellar pocket. Long back flagellum has thin mastigonemes. Proximal area of short flagellum is covered
with flat oval scales. Transitional flagellant zone has no spiral or other additional elements. Transverse plate is localized
above cell surface. Kinetosomes are parallel to each other. Vesicular nucleus and Golgi apparatus have typical structure.
Oval mitochondria contain tubular cristae. Within cytoplasm, extrusive organelles (kinetocysts) containing amorphous material
and capsule were found. The latter consists of muff and cylinder. Plasmodial and cystic phases of development have not been
discovered. Contractile vacuole is absent. The resemblance between Thaumatomastix sp. and other thaumatomonads has been discussed.
Keywords
Thaumatomastix sp.–ultrastructure–scales–kynetocysts–
Thaumatomonadida
In the years 1994–2005, the values of the integrated index IP’ at some stations of the Neva Bay changed from 38.1 to 81.9%, water quality changed from class 3 to class 5, and the states
of some areas of the ecosystem that were evaluated as “tense” went to “catastrophic.” The integrated mean assessment of water
quality according to the IP’ index over the entire Neva Bay throughout 12 years (1994–2005) remained relatively stable, waters were assessed as “polluted”
(fourth class), and the state of the ecosystem was considered “critical.” The state of the eastern part of the Gulf of Finland
in 1994–2005 was less favorable. The species diversity of zoobenthos in the resort zone of the eastern part of the Gulf of
Finland is considerably lower than in the Neva Bay. Waters of the resort zone of the eastern part of the Gulf of Finland in
1994–2005 were assessed as one class lower than in the Neva Bay, i.e., as “polluted-dirty” (fourth-fifth class), and the state
of the ecosystem was assessed as being in a “crisis.” In the resort zone, there was a decline in species diversity and abundance
and biomass of benthic animals; i.e., all characteristics of the degradation of benthic animal communities were observed.
The structure of the predatory freshwater flagellate Colpodella pseudoedax was studied. The cell was found to contain two heterodynamic flagella, three-membrane pellicle, micropores, subpellicular
microtubules, microtubular open-side conoid, roptries, micronemes, extrusive organelles (trichocysts), and mitochondria with
vesicular and tubular cristae. Upon discharge, trichocysts form cross-striated bands. A thin-walled cylinder lies in the transitional
zone of the flagella. Cells reproduce by means of longitudinal binary fission. This species differs from similar C. edax by their smaller cell size and lack of reproduction cyst. Similarities between C. pseudoedax and other colpodelids, as well as between colpodellids and perkinseids and sporozoans, are discussed.
In 1989–2005 the qualitative composition and seasonal and inter-annual dynamics of the total biomass of phytoplankton, chlorophyll
a content, hydrological, and hydrochemical parameters were studied in the Russian zone of the Vistula Lagoon in the Baltic
Sea. The results of these observations were compared to the data obtained in the 1950s and 1970s. The structural reorganization
of phytoplankton was revealed, testifying to the negative changes in the ecosystem under conditions of anthropogenic pollution
and eutrophication, climate warming, and increasing salinity.
A review of data on the phytoplankton primary production in the Neva Estuary for the period of 1980–2000 is presented. The
dynamics of primary production is affected by a complex estuarine geomorphology, geochemical boundaries, reconstitution and
sedimentation processes, and deep currents. The maximal primary production is usually observed for the areas of the geochemical
boundaries in the central part of the Neva Estuary. A positive correlation was found for the concentration of mineral particulate
matter and concentration of total phosphorus. The increase in the anthropogenic load has a significant impact on the trophic
status of the estuary.
This article reviews the current viewpoints on the definition of an estuary and the state-of-the-art and most important perspectives
of the estuarine and coastal studies that were discussed at the 42nd Estuarine and Coastal Science Association Symposium (ECSA)
“Estuarine Ecosystems: Structure, Function and Management” (16–22 September 2007, Svetlogorsk-Kaliningrad, Russia). This was
the first ECSA symposium held in the Russian Federation. The symposium participants discussed the peculiarities of the hydrological
regime, the ecosystem structure, biodiversity, functions, water quality evaluation, and management of estuaries worldwide.
Important generalizations were made on the possibility of distinguishing the impact of natural and environmental stress in
estuaries, a description of some principal processes within salinity gradients, and the application of basic elements of the
theory of ecosystem functioning to estuarine ecology. The 42nd ECSA symposium illustrated the research priorities of estuarine
studies and settled recommendations for future investigations aimed at applying the holistic approach to evaluate and forecast
estuarine ecosystem alterations and management.
The indices of the cellular and humoral components of natural immunity in bream from parts of the Rybinsk Reservoir with different
extents of contamination are studied. Considerable differences were revealed in a range of parameters between the fish sampled
in the Sheksninskii reach, which receives waste-waters from the Cherepovets industrial center, and the fish from the relatively
unpolluted Molozhskii reach. An analysis of the data shows evidence for the active state of the mechanisms of nonspecific
resistance in the fish from polluted sites.
Key wordsbream-Rybinsk Reservoir-industrial wastes-humoral indices of nonspecific immunity-leucogram
The viability of bream, roach, and blue bream F
1hybrids at early stages of their development is analyzed. Viability is controlled according to parameters of the survival
rate at stages from fertilized eggs to yearlings. During embryogenesis, significant stages (blastula—gastrula and hatching)
are revealed by the amount of losses. The viability of hybrids of the first generation (compared to pure species) from the
hatching stage and in the subsequent development constantly increases. At the stage of fingerlings, the viability of F
1hybrids significantly exceeds that of pure species, which points to the heterozygous effect according to the parameters of
hybrid survival for the first generation, which is absent in embryogenesis.
Key wordshybridization-viability-embryogenesis-postembryonic stage-heterozygous effect
Seven copepod species (potential intermediate hosts of Ligula intestinalis L.) are recorded in the Vistula Lagoon. Megacyclops viridis (Jurine) and Diacyclops bicuspidatus (Claus) are dominant species among the Cyclopoida group and may be the main potential first intermediate host of L. intestinalis. Cytopoidae is unevenly distributed in the lagoon. The parts of the lagoon with high crustacean densities and high levels Seven copepod species (potential intermediate hosts of Ligula intestinalis L.) are recorded in the Vistula Lagoon. Megacyclops viridis (Jurine) and Diacyclops bicuspidatus (Claus) are dominant species among the Cyclopoida group and may be the main potential first intermediate host of L. intestinalis. Cytopoidae is unevenly distributed in the lagoon. The parts of the lagoon with high crustacean densities and high levels
of bream infestation coincide. The peaks of Cyclopoidae abundance and the highest infestation of the bream by L. intestinalis were recorded in 1998–2000. This study shows that bream infestation in the Vistula Lagoon is directly connected with the of bream infestation coincide. The peaks of Cyclopoidae abundance and the highest infestation of the bream by L. intestinalis were recorded in 1998–2000. This study shows that bream infestation in the Vistula Lagoon is directly connected with the
presence of freshwater copepods (the first intermediate hosts of L. intestinalis), its abundance, and its spatial distribution over the lagoon area. presence of freshwater copepods (the first intermediate hosts of L. intestinalis), its abundance, and its spatial distribution over the lagoon area.
Persistent organic pollutants (POPs) were found in bottom sediments and muscles of a freshwater fish, bream (Abramis brama L.), from the Rybinsk Reservoir. The contents of POPs decreased in the following order: PCBs > DDT > HCH > HCB. The POPs
contents vary within the ranges of 0.14–50.8, 1.8–6.8, 0.64–2.6, and 0.06–0.41 \gmg/kg wet weight for fish and 24.8–425.6,
2.3–27.1, and 0.34–0.83 fug/kg dry weight for bottom sediments (except for HCH), respectively. The highest and lowest POPs
levels were found in the Sheksna and the Mologa reaches of the reservoir, respectively. The differences in the spatial distribution
of POPs in the reservoir relate to the ways that contaminants enter and migrate in the waterbody but not to various compositions
of bottom sediments. The waste waters of the city of Cherepovets are the main local source of POPs in the Sheksna reach of
the reservoir; in the Mologa reach, the contaminants enter with surface runoff and through global transboundary and local
atmospheric transports from the Cherepovets industry. The qualitative composition of POPs evidences their continuing income
to the reservoir. Considering the revealed levels of POPs accumulation and their legislative safe environment levels, it should
be concluded that PCBs represent the highest environmental threat to the reservoir’s ecosystem.
Key wordsPOPs-PCBs-OC pesticides-bottom sediments-fish-bream-Rybinsk Reservoir
The heuristic analysis of the relationship between the parameters of equations of linear (L. von Bertalanffy) and allometric
shell growth was carried out on Unio pictorum (Linnaeus, 1758), U. tumidus Retzius, 1778, and U. crassus Retzius 1778 (Unionidae) from European Russia. Growth constants of the shell, k, were studied for length (k
L
), height (k
h
), and convexity (k
C
). It was shown that the ratios of growth constants (k
h
/k
L
, k
C
/k
h
, and k
C/k
L
) and parameter bfrom the allometric equations (h=aL
b
;B=ah
b
; C=aL
b
) are connected by a strong negative correlation. If the b parameter is more than 1 (positive allometry), the growth constant relations are less than one, if b < 1 (negative allometry), the growth constant proportions are more than 1, and, in case when b is close to 1, (isometry), the growth constant proportions are also close to 1. All three types of allometric growth (isometry
and both positive and negative allometry) are observed in the studied mussels.
The effects of hydrological conditions and morphometry of the temporary waterbodies on the structure, abundance, and biomass
of crustacean zooplankton are described. This study was performed in the southeast of the European part of Russia. The existence
duration (hydrological regime) of the temporary waterbodies has the most profound effect on the zooplankton patterns. A significant
effect was observed for the number of dominant species, the zooplankton biomass, the calanoid-cyclopoid ratio, and the Shannon
index. The brackish lagoons were characterized by the highest biodiversity and abundance and the lowest values of these parameters
were found in the steppe puddles and waterbodies of terraces above the flood-plain in the river valleys.
It has been shown that chronic exposure to dietary mercury results in the intensive accumulation of this metal in roach yearlings.
The concentrations of accumulated mercury in their organisms were proportional to the amount of metal added to water of experimental
tanks. Increased Hg content in the organisms (0.05–0.16 mg/kg) of developing juvenile roaches decreases the activity of digestive
carbohydrases and the affinity of enzymes to substrate with subsequent retardation of rates of initial stages of digestion.
The accumulation of mercury in the organism is accompanied by an increase in the body length and weight in the exposed fish
compared to the control. The possible mechanisms responsible for such an increase in fish with high Hg body burdens, and with
a simultaneous decrease in carbohydrate metabolism rate, are discussed in the paper.
The spatial regularities of the accumulation of heavy metals in two ecological morphs of whitefish of the Pasvik River (northern
Fennoscandia) under long-term pollution have been investigated. It was revealed that the accumulation of priority pollutants
(Ni and Cu) in fish declines the further you go from the source of pollution. The concentration of Hg in the tissues of fish
from the Pasvik River was determined for the first time. It was found that metal accumulation depends on the ecological morphs
of the fish, the natural conditions of the waterbodies, and the intensity of pollution. The specific features of heavy-metal
distribution in the “bottom sediment-fish organism” system were determined. These may indicate the heterogeneity of the pollution
processes of the Pasvik system of waterbodies.
Keywordsheavy metals–gradient pollution load–
Coregonus lavaretus
–global pollution
The abundance and taxonomic and trophic structures of the community of planktonic heterotrophic nanoflagellates, as well as
the quantitative distribution of bacteria as their main object of food, have been studied in six lakes of Karelia with differing
pH values, concentrations and compositions of organic substances, and degrees of anthropogenic load. Thirty-eight species
and forms of colorless flagellates from seven orders and groups of uncertain taxonomic statuses have been recorded. Most of
them belong to the trophic group of bacteriodetritophages. The minimal abundance and the lowest diversity of flagellates have
been documented in clear- and brown-water lakes with low pH values, and maximal values have been observed in the polluted
Kondopoga Bay in Lake Onega.
Keywordsheterotrophic nanoflagellates–abundance–diversity–bacteria–acidic and neutral lakes
Early germ cell development in Persian sturgeon appears to be faster in the marine environment than in aquaculture conditions.
Adaptation plasticity differs significantly for gonad formation and sex determination in the sturgeon fry and depends to differing
extents on the temperature. The sturgeon gonads are more sensitive to low temperatures on the early stages of sex determination
than in the period of gonad formation; the differences between sexes are preconditioned by the earlier start of sex determination
in females when compared to males. The rates of the early gonad and germ cell development in sturgeon are conditioned by its
reproduction season. In the population of the late spring race, the delay in both early sex determination and germ cell development
stays even for the ages of 1+, 2+, and 3+ when compared to the population of the early spring race. The biophysiological quality
of parents is transmitted to their offspring.
Keywordsearly ontogenesis–sex differentiation–gonium–germ cell development–growth rate–heterochrony
The influence of sublethal concentrations of Roundup (25 and 50 mg/l of the active compound glyphosate) was studied in the
Daphnia magna Straus of successive generations. The toxic effects were assessed by the parameters of fecundity, quality of progeny, and
linear sizes of daphnia, as well as by the activities of carbohydrases and proteases. The effect of the toxicant may be traced
both in the parent specimens and in the specimens of successive generations. No adaptation to Roundup’s toxic impact was revealed
for four generations of Daphnia magna. However, a considerable decrease in resistance to the herbicide was noted in the fourth generation when compared to the
maternal line.
The total amylolitic activity and sucrase activity in the Amur sleeper intestine are similar to those in typical and facultative
benthophages. The optimal temperature of starch hydrolysis is 50 °C. The sleeper’s carbohydrases are more tolerant to the
increase in water temperature during winter than similar enzymes in cyprinids.
A modern molecular genetic method has been adapted to study microorganisms associated with fish. A procedure for total DNA
isolation from various organs and tissues of fish has been developed. Besides fish freshly caught, frozen and salted specimens
were used. A bacterial PCR product was shown to amplify with highly conservative primers at an annealing temperature of 70–72°C
from fish gills, liver, intestine, and skin.
The combination of molecular-genetic techniques used in the study is applied to investigate microorganisms associated with
macrophytes. The method of enzymatic lysis with phenol-chloroform extraction is optimal for the total bacterial DNA isolation
from both periphyton organisms and enriched cultures. Amplifying the total DNA on conservative primers at the two-step PCR
regime is recommended. An analysis of the taxonomic diversity of the microbial community from biofilm on the reed grass and
in the enriched cultures propagated on various growth media has been carried out. The results have revealed a high diversity
of periphyton microorganisms associated with reed grass, including representatives of such phylogenetic lines as proteobacteria
(α, β, γ, and δ subgroups), Bacteroidetes/Chlorobi, Chlamydiae/Verrucomicrobia, and cyanobacteria. The low diversity of sequences
in enriched cultures is represented by dominating genotypes of Cellvibrio with a high percentage of homology and uncultivated bacilla.
The dimensional specifications and morphology of the resting eggs of ten conchostracan species (Cyzicus tetracerus, Eocyzicus orientalis, Caenestheria davidi, C. perrieri, Leptestheria dahalacensis, Eoleptestheria ticinensis,
Limnadia lenticularis, Imnadia yeyetta, Lynceus brachyurus, and L. dauricus) have been studied. The data are presented on the number of eggs produced by females. Unlike other crustaceans, no correlation
between the eggs size and their quantity was found. Although the number of eggs can vary one to two times, their size is relatively
stable (variation coefficient <5%). The wet (1.5–5.4 μg) and dry (0.41–0.93 μg) weights of eggs and the share of clutch (11.4–21.6%)
in the female’s wet weight were determined for eight species. The polyfunctionality of the external envelope of the egg was
considered under anhydrobiosis conditions.
KeywordsConchostraca–Laevicaudata–resting eggs–morphology–wet and dry weight–adaptive possibilities
Brine shrimp Artemia (Crustacea, Anostraca) diverge in biometry and nutritional quality. These differences in Artemia characteristics are significant not only from strain to strain but also from one harvest to another within same strain. The
main objective of this study was to compare Artemia salina cysts harvested from Sabkhet El Adhibet (southeast Tunisia) on different dates between 2002 and 2007 with special regard
to their use in aquaculture, using cysts and naupliar biometrics, protein, carbohydrate, and lipid content. Fatty acid profiles
as well as hatching characterisation were also evaluated. Hydrated cysts measures ranged between 258.1 and 263.7 μm, while
the freshly hatched nauplii of Artemia measures ranged between 458.1 and 476.1 μm. Lipid contents of the samples ranged from 16.2 to 18.3% of the dry weight. Fatty
acid profiles showed that cysts from Sabkhet El Adhibet contain a high quantity of eicosapentaenoic acid (20: 5n-3) with a
percentage ranging between 7.8 and 14.3% of the dry weight. The highest hatching efficiency was obtained for decapsulated
cysts collected in 2007 (139500 nauplii g−1 of cysts). Cysts treated with hydrogen peroxide had a hatching percentage of 14.49 to 42.99%. The hatching synchronization
time for untreated cysts varied between 23.5 to 27.4 h.
Key wordsSabkhet El Adhibet-
Artemia salina cysts-protein-carbohydrate-lipid contents
The biology, morphology, and ultrastructure of the freshwater rapacious flagellate Colponema aff. loxodes, which attacks bodonids and chrysomonads, are studied. The flagellate is characterized by three-membrane alveolar pellicle,
vesicular nucleus, two heterodynamous flagella, two microtubule bands which armor the longitudinal groove, and mitochondria
with tubular cristae. Toxicysts (thread-organelles) are found in the cytoplasm. The posterior flagellum is characterized by
the proximal fold. Micropores are completely absent. After being caught, the prey is taken into the longitudinal groove. Vegetative
swimming cells are present in the life cycle. No reproduction or latent cysts are found. The taxonomical position of Colponema aff. loxodes is discussed in comparison with other colponemids and protists.
Key wordscolponemids-alveolates-ultrastructure-morphology
On the basis of the data obtained during field observations in the summer low water period of 2001, the patterns of chlorophyll
distribution and its relation to hydrological and hydrochemical factors in two eutrophic reservoirs of the Middle Volga are
studied. The hydrological structure of the Gorky Reservoir, where the Volga water mass dominates, is homogeneous, while in
the Cheboksary Reservoir along with the eutrophic Volga waters, the mesotrophic Oka water masses can be distinguished keeping
their abiotic and biotic features over a long distance. Phytoplankton in the two contiguous reservoirs with different flow
regimens and anthropogenic loads responds differently to the external influence. An autotrophic community in the Gorky Reservoir
is more stable and depends little on abiotic factors which account for ∼63% of the explained chlorophyll variation. In the
Cheboksary Reservoir under maximal for the Volga cascade flow velocity and anthropogenic load, the development and distribution
of phytoplankton are almost completely (R
2 = 0.93) controlled by these factors. The trophic state of the reservoirs has not changed as compared to the beginning of
the 1990s.
The study of samples from various waterbodies (rivers, lakes, reservoirs, and seas) has shown that S. agassizensis manifests a significant morphological variability of qualitative and quantitative characters (the valve diameter and its
relief, the mantle height, and the presence and arrangement valve face fultoportulae) which distinguish this species from
other species with similar a morphology (S. neoastraea, S. heterostylus, S. alpinus, and S. maximus). Original and literature data on the morphology, ecology, and distribution of S. agassizensis has allowed the author to specify its taxonomic position, refer the species to the synonymy of S. neoastraea, and extend the diagnosis of the latter.
Microbial communities in the bottom sediments of the Akademichesky Ridge, Lake Baikal, were studied. The samples were taken
by deep drilling BDP-96 (a 100-m core). Vertical distribution of the prokaryotes with different physiological characteristics
was studied for the core. The phylogenetic analysis of the organotrophic laboratory-reared microorganisms revealed the clusterization
of Baikal strains and species which have not been identified yet.
Key wordssediments-Lake Baikal-prokaryotes-phylogenetic analysis
The results of a study of alderfly larvae (Sialidae, Megaloptera) from over 400 small lakes and ten large lakes and rivers
in Northern Finland, Norway, and Murmansk oblast are presented. The distribution of five species of larvae in relation to
the landscape, size of water bodies, hydrological type of water bodies, type of habitats, pH, water color, etc., is considered.
Possessing a relatively higher plasticity and tolerance to environmental conditions, Sialis larvae were found more often and made the maximum contribution to the biomass of littoral macroinvertebrate communities in
small north taiga and tundra lakes, slow water courses, on soft sediments, in vegetation, in weakly humic waters, and in circumneutral
and weakly alkaline waters. High ecological plasticity, including pollution, is found in the larvae of S. morio Klingstedt and S. lutaria L.
Experiments were conducted on growing mixed cultures of green Ankistrodesmus arcuatus Korsch and diatom Diatoma elongatum (Lyngb.) algae with and without ciliates Cyclidium glaucoma Ehrenberg and Paramecium caudatum Ehrenberg in accumulative and perfusion cultures. Both alga species successfully developed in the presence of ciliates despite
their grazing on both alga species; however, in their absence, Ankistrodesmus arcuatus were suppressed and did not develop. It is supposed that ciliates contribute to the stabilization of the community not only
as predators but also by excreting dissolved reduced nitrogen into the environment as a result of their vital functions.
The species composition of diatom algae in the Polistovo-Lovatskii sphagnum tract (Rdeiskoye bog, Novgorod oblast) \are studied.
The systematic and ecological-geographical analyses of the flora are performed. A total of 256 species and intraspecific taxa
differing in ecological specificities and frequencies of occurrence in samples are revealed. A considerable number of centric
diatoms is found. It is shown that primary and secondary diatom communities are formed in large sphagnum tracts. The horizontal
heterogeneity of diatom communities in sphagnum bog is revealed. The species diversities of diatom algae in different bogs
are compared.
The results of algological studies in water bodies of the Manikuyakha River basin are discussed. A total of 172 taxa of algae
have been identified, including 65 taxa new for the Bol’shezemel’skaya tundra and 130 taxa (three genera, 116 species, and
six varieties) found in water bodies of the Polar Urals for the first time. The current state of these water bodies has been
assessed on the basis of hydrochemical and algological indices.
The electron microscopy study of algae from Lake Elgygytgyn and the water bodies of its basin has revealed 21 taxa of centric
diatoms of specific and intraspecific ranks. Nine new species and varieties have been found, including Aulacoseira distans var. nivaloides, A. distans var. septentrionalis, Discostella guslyakovyi, which are rare for the flora of Russia; an endemic species (?) Pliocaenicus seckinae; and six interesting forms from the genus Aulacoseira identified only to the genus. The list of Centrophyceae of Beringia has been broadened.
Key wordsChukotka-Lake Elgygytgyn-flora-diatom algae-Centrophyceae
The total amylolytic activity and activity of alkaline phosphatase in the intestine mucosa of larvae and fries of roach, blue
bream, and perch change both during the process of individual development and during the day. Maximal intensities of juvenile
feeding was observed primarily in the morning and evening hours. The pattern of diurnal alkaline phosphatase activity correlates
to a greater extent to intensity of juvenile feeding, in comparison to the pattern of total amylolytic activity. In planktivorous
blue bream, such regularity is more pronounced than in benthivorous roach. The total amylolytic activity in fries of roach,
blue bream and perch correlates to fish type of feeding.
An ecobiomorphological profile of the water soldier Stratiotes aloides L. has been established based on materials obtained in the western Siberian part of the species range. This species has been found to be a perennial (vegetatively-oligenial) polycarpic rooted rosulate stolon-turion vegetatively-mobile surface-blossoming mesotrophic conditionally limnetic detritus-pelophilic hydatophyte.
The distribution of preimaginal phases of black flies in the basin of the mountain river Sema (North Altai) is analyzed based
on quantitative data. The studies were carried out at the altitudes of 300–2500 above sea level. The structural elements of
the black fly community in the altitudinal belts were distinguished. The distribution of black flies on the landscape and
ecological profiles is discussed. The sequence of changes in the black fly community along the river is considered. An assessment
of the importance of the environmental factors determining the unevenness of the black fly population in the Sema River basin
is given.
