Dimitri A Pavlov | Moscow State University (original) (raw)

Books by Dimitri A Pavlov

⎯The methods of scanning and transmission electron microscopy are used for the investigation of e... more ⎯The methods of scanning and transmission electron microscopy are used for the investigation of external morphology and ultrastructure of spermatozoa in scorpaenoid fishes Parascorpaena picta, Dendro-chirus zebra (Scorpaenidae), and Synanceia horrida (Synanceiidae). Based on the literature data, a comparison with other species of the genera Scorpaena, Sebastapistes, and Scorpaenopsis (Scorpaenidae) is conducted. In the studied species, the spermatozoon consists of the rounded head (its length is slightly smaller than its width), moderately developed midpiece, and flagellum. P. picta differs from the other species in the presence of the widening of the cytoplasmic channel surrounding the initial part of the flagellum, the largest numbers of mitochondrial sections, and the longest flagellum. S. horrida does not differ significantly from the representatives of the family Scorpaenidae. However, based on the contour of the head and midpiece (elliptic Fou-rier analysis), there is a trend to the separation of S. horrida from P. picta and D. zebra. The data on comparative spermatozoa morphology are discussed in relation to current phylogenetic schemes.

—Two color morphs of freckled goatfish Upeneus tragula with different Vietnamese names and mainly... more —Two color morphs of freckled goatfish Upeneus tragula with different Vietnamese names and mainly black and red body coloration of fresh dead exemplars are found off Hon Thóm (Thom Island), the largest island of An Thoi Archipelago located to the south of Phu Quoc Island, Gulf of Thailand, South China Sea. The presence of the morphs may be connected with the occurrence of two sympatric stocks or with color variation within a single stock. To test these hypotheses, red color content on the body (based on digital analysis of images) and gonadal condition is compared in both morphs. Body coloration does not depend on the sex of the fish. The black morph differs from the red morph in a smaller body size (12.7 vs. 16.4 cm FL on average), and it is represented by mainly immature individuals of both sexes (mean gonadosomatic index of the females 0.5 vs. 2.0%). It is proposed that the change of body coloration is associated with sexual maturation, and it occurs in the ontogeny within a single stock.

The culture of ornamental coral reef fish species conserves natural reef resources by offering al... more The culture of ornamental coral reef fish species conserves natural reef resources by offering alternatives to wild capture and develops a new source of organisms for the aquarium trade. Hormonal stimulation of maturation of sex cells facilitates obtaining large numbers of eggs and larvae available for subsequent rearing and allows researchers to collect valuable knowledge about life histories of the species to improve the management of natural stocks. In the monograph, detailed information on hormonal stimulation of oocyte maturation and ovulation, morphological changes of oocytes during maturation, ultrastructure of gametes, assessment of egg and sperm quality, embryonic and larval development, and transition of the larvae to exogenous feeding is presented for three model species from the families Acanthuridae (scopas tang Zebrasoma scopas) and Pomacentridae (threespot damselfish Dascyllus trimaculatus and scissortail sergeant Abudefduf sexfasciatus), which are used in aquaria trade. In addition, a brief description of the experiments on hormonal stimulation of oocyte maturation and ovulation is given for 16 other ornamental coral reef fish species. The results are discussed based on recent achievements in developmental biology and marine aquaculture. The book is designated for ichthyologists, zoologists, marine aquaculturists, and students of the universities or colleges.

The Atlas is the second edition of the monograph “Freshwater Ichthyoplankton of Russia (Atlas)”, ... more The Atlas is the second edition of the monograph “Freshwater Ichthyoplankton of Russia (Atlas)”, Moscow University, 1998. The illustrations of prelarvae (free embryos), larvae, and juveniles of 175 fish species are included. Brief characteristics of reproductive biology are given for each family and species. The illustrations are accompanied by morphological characteristics. A short review on the reproduction of fishes and development of the young is represented. The book is designated for ichthyologists, zoologists, fish breeders, and students of the universities or colleges, as well as for nature-lovers.

The features of reproductive biology are analyzed in different species and forms of salmonids of ... more The features of reproductive biology are analyzed in different species and forms of salmonids of the genera Salmo and Oncorhynchus. Their embryonic and larval development is illustrated. Theoretical opinions on the early ontogeny of teleost fishes and salmonids are discussed. The variation of early ontogeny under the effect of temperature and salinity is described. The origin of salmonids and evolution of their early ontogeny are discussed.

Papers by Dimitri A Pavlov

Otolith morphology and microstructure of the sagitta are described in freckled goatfish Upeneus t... more Otolith morphology and microstructure of the sagitta are described in freckled goatfish Upeneus
tragula. The first increments (from the second to sixth or eighth) are the most well defined, and subsequent
zones of less contrasting increments are bounded by increments with more contrasting borders. These borders
are less expressed close to the edge of the sagitta. The width of the majority of increments ranges from 1.5 to
2.5 µm. Based on the results of the experiments on in vivo marking of the sagittae, daily periodicity of incre
ment deposition is supported. Age composition of the populations from the coastal zone of Vietnam (Nha
Trang and Ha Long bays) is assessed based on the calculation of daily increments. The growth rate of the
fishes is characterized by a substantial variation. In Nha Trang Bay, the females grow more rapidly than the
males, and the growth rate of the fishes in Nha Trang Bay is lower than that in Ha Long Bay. Maximum age
of the fish in both bays is 3 years 99 days and 2 years 129 days, respectively.

Development of sex cells, sperm motility, and initial stages of embryonic development are descri... more Development of sex cells, sperm motility, and initial stages of embryonic development are
described in a tropical representative of the family Mullidae, freckled goatfish Upeneus tragula, from the
coastal zone of Vietnam. In Nha Trang Bay, the gonads in the majority of sexually mature females are at IV,
IV–V, and VI–IV maturity stages over the entire year , and the type of oogenesis is continuous. Anomalous
structure of oocytes is registered in 15% of investigated females. In Ha Long Bay, the gonads of almost all sex
ually mature females are at maturity stage II in December. In adult males, spermatozoa are the most numer
ous in elongated spermiducts. Based on computerassisted analysis of motility of spermatozoa removed from
a spermiduct and activated in marine water, sperm velocity reaches 53 µm/s in 1 min after activation, and the
duration of progressive movements of spermatozoa does not exceed 5 min.

Features of reproduction are described in the tropical representative of the family Mullidae frec... more Features of reproduction are described in the tropical representative of the family Mullidae freck
led goatfish Upeneus tragula from southern Central Vietnam (Nha Trang Bay) and North Vietnam (Ha Long
Bay). Sex ratios of the fishes (females : males) in Nha Trang and Ha Long bays are 0.93 : 1 and 1.2 : 1, respec
tively. In both bays, the body length–body weight relationship is not substantially different between the
females and males. In Nha Trang Bay, the females reach sexual maturity by 10.2 cm fork length (50% of indi
viduals), and the fishes spawn over the entire year. In a part of the population (on average, 23.5% of fishes),
the interruptions in spawning not associated with a certain season of the year are registered. In Ha Long Bay,
a distinct spawning interruption is observed in all fishes during winter.

Ultrastructure of envelopes of ovulated oocytes and spermatozoon ultrastructure are described in ... more Ultrastructure of envelopes of ovulated oocytes and spermatozoon ultrastructure are described in
two closely related species of the family Mullidae, Upeneus tragula and U. cf. margarethae. Oocyte envelope
is represented by the thin zona radiata and weakly expressed chorion. The spermatozoon is characterized by
the presence of elongated head with a pointed bend in its apical part and nuclear fossa reaching approximately
90% of the head length. The centriolar complex and basal part of the flagellum are located inside of the
nuclear fossa.

We describe anomalies in oocyte structure of manybar goatfish Parupeneus multifasciatus from the ... more We describe anomalies in oocyte structure of manybar goatfish Parupeneus multifasciatus from the
coastal zone of southern Central Vietnam. The anomalies are registered in the majority of cells (>80%) from
ovarian fragments of several individuals. The abnormal cells are at the periods of maturation, vitellogenesis,
and, sometimes, previtellogenesis. Possible effect of pollutants on oocyte morphology is discussed.

Gonadal differentiation and development of sex cells are described in the tropical representative... more Gonadal differentiation and development of sex cells are described in the tropical representative of the family Mullidae, manybar goatfish Parupeneus multifasciatus, using histological methods and observations of oocytes in vivo. Anatomical differentiation of the gonads is registered by approximately 5 cm fork length (FL) and 1.5 g body weight of the fish, and cytological differentiation (in the females) occurs by approximately 6 cm body length and 2.6 g body weight. In the ovaries of sexually mature females before spawning, oocytes of all phases and periods of development can be found. Based on the gonadal structure and
frequency distribution of oocyte diameter, the type of oogenesis is continuous.

The growth of individuals is analyzed in the mass tropical species manybar goatfish Parupeneus mu... more The growth of individuals is analyzed in the mass tropical species manybar goatfish Parupeneus multifasciatus from the Nha Trang Bay of the South China Sea. The relationship between the body weight and body length is determined for the females and males. Among the fishes larger 180 mm fork length (FL), the males prevail. Linear growth of the sagitta is characterized by negative allometry in relation to body length, and sagitta growth in length is faster than in width. Age of fish assessed based on the analysis of daily increments on the sagitta does not exceed three years, and the majority of individuals reach the first sexual maturity by the age of one year. The growth rate of the fish is characterized by a large individual variation.

Among teleost percoid fishes (Percomorpha), the subordes Scorpaenoidei (Scorpaeniformes) and Zoa... more Among teleost percoid fishes (Percomorpha), the subordes Scorpaenoidei (Scorpaeniformes) and
Zoarcoidei (Perciformes) are of particular interest due to the presence of intermediate stages between oviparity and viviparity in several species. We analyze the features of reproductive biology in the fishes of the suborder Scorpaenoidei, including morphology of the urogenital system, gametogenesis, gamete ultrastructure, and embryonic development. The new materials are represented for three tropical coral reef fish species with external insemination from the family Scorpaenidae (Scorpaenopsis possi, Sebastapistes cyanostigma, and Dendrochirus zebra). In particular, a hypertrophied urinary bladder used for storage of mature sperm for insemination of pelagic egg clutch is described in the males. Evolutionary transition to viviparity within the family Sebastidae is discussed. Alternative reproductive strategies are registered in viviparous fishes from the suborders Scorpaenoidei and Zoarcoidei. They are connected with the production of a large number of morphologically weakly developed larvae and a small number of individuals at the juvenile state, respectively.
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In tropical representatives of the family Mullidae, the ultrastructure of oocyte envelopes (Parup... more In tropical representatives of the family Mullidae, the ultrastructure of oocyte envelopes (Parupeneus multifasciatus and Upeneus tragula) and spermatozoa (P. multifasciatus and P. barberinoides) is studied. The egg envelopes include the single-layered zona radiata and weakly expressed chorion. The spermatozoa are characterized by a presence of the oval head flattened on a side and deep nuclear fossa reaching approximately 90% of the head length. The centriolar complex and basal part of the flagellum are located inside of the nuclear fossa.

Otolith morphology and microstructure of the sagitta are described in the mass tropical species m... more Otolith morphology and microstructure of the sagitta are described in the mass tropical species manybar goatfish Parupeneus multifasciatus. The hatch check is absent on the sagitta, and the appearance of the first contrasting increment is connected with the transition of the larva to exogenous feeding. The increments are distributed within several concentric zones, and each zone is separated by the more pronounced dark areas (in transmitted light) of the increments (checks). The number of increments within a zone is variable; and the modal group (with the exception of the first zone from the primordium to the first check) includes from six to ten increments. In the juveniles, the periodicity of increment formation on the sagitta ranges from <1 to >3 in a day, but it is close to one increment per day in the individuals larger than 86 mm FL and 11 g in weight. The number of increments deposited in a day does not depend on the growth rate or feeding frequency of the juveniles.

Features of reproductive biology and the stages of early ontogeny are described in the mass tropi... more Features of reproductive biology and the stages of early ontogeny are described in the mass tropical species manybar goatfish @Parupeneus multifasciatus@. In general, in the catches represented by mainly sexually mature fishes, the females prevail, but the males prevail in the largest size classes. The females reach the first sexual maturity by approximately 110 mm fork length, and they are characterized by continuous oogenesis and egg deposition in batches. The fish spawn over the entire year with the trend to lower values of the gonadosomatic index (GSI) of the females from June to October. The features of early ontogeny are compared in manybar goatfish and red mullet @Mullus barbatus ponticus@ from the Black Sea.