Morphomechanical aspects of the development of the bleak (Alburnus alburnus L.)

Morphomechanical study on the changes taking place in the course of the embryonic development of the bleak (Alburnus alburnus L.) conducted on tlle live fish in vertical and horizontal light beams, revealed that the oocyte (yolk mass) occupies some 30% of the entire egg′s volume, while the remaining 70% is occupied by the perivitelline space. The blastodisc and subsequently the embryo and the larva before the hatching always take up lateral position in the egg. No lipid droplets (structural fat), commonly occurring in the eggs of the other teleost fishes are present in the yolk mass of the bleak eggs. Biological justification of the above extraordinary phenomena as well as their adaptive importance is discussed

The Effect of an Anthropogenic Magnetic Field on the Early Developmental Stages of Fishes—A Review

The number of sources of anthropogenic magnetic and electromagnetic fields generated by various underwater facilities, industrial equipment, and transferring devices in aquatic environment is increasing. These have an effect on an array of fish life processes, but especially the early developmental stages. The magnitude of these effects depends on field strength and time of exposure and is species-specific. We review studies on the effect of magnetic fields on the course of embryogenesis, with special reference to survival, the size of the embryos, embryonic motor function, changes in pigment cells, respiration hatching, and directional reactions. We also describe the effect of magnetic fields on sperm motility and egg activation. Magnetic fields can exert positive effects, as in the case of the considerable extension of sperm capability of activation, or have a negative influence in the form of a disturbance in heart rate or developmental instability in inner ear organs

The Effect of an Anthropogenic Magnetic Field on the Early Developmental Stages of Fishes—A Review

The number of sources of anthropogenic magnetic and electromagnetic fields generated by various underwater facilities, industrial equipment, and transferring devices in aquatic environment is increasing. These have an effect on an array of fish life processes, but especially the early developmental stages. The magnitude of these effects depends on field strength and time of exposure and is species-specific. We review studies on the effect of magnetic fields on the course of embryogenesis, with special reference to survival, the size of the embryos, embryonic motor function, changes in pigment cells, respiration hatching, and directional reactions. We also describe the effect of magnetic fields on sperm motility and egg activation. Magnetic fields can exert positive effects, as in the case of the considerable extension of sperm capability of activation, or have a negative influence in the form of a disturbance in heart rate or developmental instability in inner ear organs

Morphomechanical changes in eggs of the noble crayfish (Astacus astacus L.) during embryogenesis

Stale wzrastające zanieczyszczanie środowiska oraz presja obcych gatunków raków, a przede wszystkim wyniszczenie przez dżumę raczą, spowodowało znaczne ograniczenie występowania stanowisk raka szlachetnego (Astacus astacus L.) w Polsce. Lepsze poznanie biologii rozrodu i embriogenezy tego gatunku raka jest konieczne nie tylko do jego ochrony przed wyginięciem, ale również poprawy warunków chowu i hodowli. Rozwój zarodkowy raka szlachetnego w warunkach średniej temperatury 8 ± 2°C trwał 2100 D°. Podział żółtka przebiegał w bardzo wolnym tempie i kończył się dopiero po upływie 352 D°. Pierwsze półkoliste zawiązki zarodka zaobserwowano w 592 D°. Zamykanie się blastoporu nastąpiło w 928 D°. W 1200 D° zarodek przybrał postać naupliusa. Na tym etapie widoczne były przydatki: anteny I i II pary oraz żuwaczki. Około 1500 D° serce podjęło pracę. Na krótko przed wylęgiem (1800 D°) pojawił się w oczach pigment, zaś na powierzchni zarodka zaobserwowano równomierne rozmieszczenie komórek barwnikowych. Po przeanalizowaniu zmian morfometrycznych jaj raka szlachetnego stwierdzono, że objętość w trakcie embriogenezy zwiększała się z 9,26 ± 0,44 mm³ do 13,5 ± 0,44 mm³ na krótko przed wylęgiem. Pomiary wytrzymałości mechanicznej osłonek jajowych ujawniły, że była ona dość znaczna na początku embriogenezy (ponad 150 ± 20,2 g) i zmniejszała się w trakcie rozwoju embrionalnego do wartości 83,5 ± 7,1 g w chwili wylęgu. Współczynnik S/V na początku rozwoju zarodkowego wynosił 2,291 i w miarę trwania embriogenezy zmniejszał się do 2,017.Constantly increasing pollution of the environment, invasive species, and a great harm caused by the plague (Aphanomyces astaci) contributed to a significant decrease of the noble crayfish (Astacus astacus) in Poland. Expanding the knowledge of the biology, reproduction and embryogenesis of the noble crayfish is necessary not only for its conservation, but also to improve its farming. Our study shows that embryogenesis of the noble crayfish at an average temperature of 8 ± 2°C lasted 2100 D°. The partition of the vitellus showed a rather slow rate and ended after 352 D°. First semicircular germs of the embryo were observed at 592 D°. Blastopore closed off at 928 D°. At 1200 D° embryo assumed the shape of nauplius, and at this stage the antennae of I, II pair and mandibles were visible. At about 1500 D° the heart became active. Shortly prior to hatching (1800 D°) eyes were pigmented, while steady distribution of pigment cell was observed on the surface of the embryo. After the analysis of morpho-mechanical changes in eggs of the noble crayfish, we found that the volume of eggs in the course of embryogenesis increased from 9.26 ± 0.44 mm³ to 13.5 ± 0.44 mm³ just shortly prior to hatching. Mechanical resistance of egg membrane to applied pressure was considerable - 150.0 ± 20.2 g at the beginning of embryogenesis, and dropped at hatching to 83.5 ± 7.1 g. The S/V coefficient at the beginning of embryonic development was 2.291 and decreased during embryogenesis to 2.017

The structure and the embryogenetic role of eggs and egg membranes of Ancistrus dolichopterus (Actinopterygii: Siluriformes: Loricariidae)

Background. Bushymouth catfish, Ancistrus dolichopterus Kner, 1854 has raised interest among ornamental fish keepers. Its natural populations are seriously threatened by fishing pressure. The reproduction of this species is difficult to perform (in captivity) and to observe because it occurs at night in shaded areas—most frequently in hiding spots. This study was intended to describe the eggs and their membranes of bushymouth catfish known to provide a parental care during egg development. A special focus of this study was directed towards the microstructure of membranes protecting life cells, and known to be impacted by the environmental conditions the egg morphometric analysis, as well as embryonic development. Materials and methods. The material for the study consisted of the eggs of 3 pairs of bushymouth catfish obtained as a result of their spawning in an aquarium culture. The fertilised eggs were incubated at a constant temperature of 24 ± 0.2°C in water of hardness 17°n, pH 6.5. The utrastructural details of egg membranes were viewed under scanning electron microscope (SEM). Also egg membrane resistance and egg diameters were determined. Images of eggs and newly hatched larvae were measured and analysed. Results. Average egg diameter was 2.98 mm and surface-to-volume ratio (S/V) was 2.01. Internal and external layers of egg membranes showed various structure peculiarities in the surface microstructure of studied eggs. We found that in comparison to other fish the thickness of egg membrane in the bushymouth catfish was high (26.05 µm). External layer had no pores leading to external radial zone (zona radiata externa), however, some specific honeycomb-like formations were visible. The resistance of the egg membrane was 54 ± 1.7 g and the egg mass was 0.017 ± 0.0001 g. The correlation between the resistance and the thickness of the egg membranes was not high, but the correlation between the mass and the resistance  was significant. Conclusion. The presently reported study constitutes a contribution to the knowledge of the eggs and embryonic development of bushymouth catfish, and its biological sense, emphasizing the morphophysiological differences between this species—living under, specific, diversified ecological conditions. Such knowledge on early developmental stages may be prove helpful in the fish culturist’s practice of this threatened and interesting species

Morphophysiological aspects of the embryonic development of ruffe, Gymnocephalus cernuus (L.) under different thermal conditions

Background. Ruffe, Gymnocephalus cernuus is a small fish inhabiting vast areas of Europe, Asia, and also North America. Its substantial geographical dispersal range in different climatic zones, in waters of different parameters indicates that this is a particularly plastic species. Recent implementation of new fish-processing machinery has increased dramatically the economical importance of ruffe, which is now treated as a gourmet food. In the wake of the increased interest in this fish we decided to study aspects of its developmental biology. Methods. Fertilised eggs and the developing embryos of ruffe were incubated under five different temperature regimes. They were monitored in two planes, horizontal and vertical, using a light microscope fitted with a digital camera and connected to a computer with a monitor and a VCR. The data collected were processed using MultiScan software.Materials and methods.Results. Perivitelline space in ruffe constitutes as much 65% of the egg volume. This facilitates movements of an embryo and enhances processes of gas exchange through mixing of perivitelline fluid. It finally contributes to the distribution of the hatching enzyme on the inner surface of the egg shell. Similarly as in the other percid fish, the lack of integration between the "lipid raft" and the embryonic disc, causes the fall of the disc on the lateral side of the vitelline sphere. This lateral position persists throughout all sequential stages of the embryogenesis. The diversified thermal regimes of the development affect the timing of the embryogenesis, as well as the condition, weight, and the size of newly-hatched ruffe larvae. The highest rate of specimens hatched in good condition-marked by the highest weight and body length-was observed at the optimal temperature range of 16-18oC. Newly-hatched larva is small (5 mm body length, 0.10 mm3 of yolk sac volume), active, and fully prepared for independent life in the water. Under the optimal temperature range, determined in the present study, the duration of embryonic development of ruffe (from fertilisation to hatching) was 2122 dh (accumulated degree-hours).Conclusion. The present study constitutes a contribution to the knowledge of the embryonic development of ruffe and its biological sense, emphasizing the morpho-physiological differences between this species-living under, specific, diversified ecological conditions-and other fish

Effects of the magnetic field on different forms of embryonic locomotor activity of northern pike, Esox lucius L

Background. The magnetic field is known to exert its influence on both adult and juvenile fishes, as well as the embryos. The effects are diversified and pertain to, practically all, life aspects of an individual. Another aspect of this issue can be the existing and still growing magnetic pollution of the natural environment. In view of the above we decided to study the embryonic motorics of fish, exemplified by pike, affected by constant- and alternating magnetic fields. Materials and methods. Eggs of pike (Esox lucius L.) after period of adaptation (control) were subjected to 30-min action of the magnetic field (constant 4 mT and alternating 15 mT). The inflicted changes in the embryonic motorics were observed under a microscope and recorded on videotape. Results. The following aspects of the embryogenesis were affected: Quasi-peristalsis (increased angular velocity and the amplitude of ectoplasmic waves-at the stages of blastula end gastrula). Heart muscle action (in alternating field-short, small acceleration in the heartbeat is followed by a sudden rise of the number of contractions). Somatic motorics (no visible effect of neither constant- nor alternate field). Conclusion. Three different mechanism of the magnetic field are taken into consideration: a) directly on actomyosin structures in the quasi-peristalsis, b) on automatic centres of the developing heart, and c) on developing structures of the central nervous system (no effect presently observed)

The rationale of building spawning grounds for migratory salmonids in the Ina River catchment based on environmental studies. Part 3. Other tributaries of the InaRriver

Wymagania środowiskowe ryb łososiowatych – łososia (Salmo salar L.) i troci (Salmo trutta m. trutta L.) oraz trudności związane z zabudową hydrotechniczną cieków, w istotny sposób ograniczają możliwość bytowania i przystępowania do rozrodu tych cennych gatunków. W pracy przedstawiono wyniki trzeciej – ostatniej części badań nad przydatnością wód zlewni rzeki Ina do budowy tarlisk dla wędrownych ryb łososiowatych. Badaniami objęto dopływy głównego koryta Iny – rzeki: Wardynka, Stobnica, Reczyca, Mała Ina, Małka i Wiśniówka. Jakość wód tych rzek badano w sezonie letnim i jesienno-zimowym w 11 punktach, w których również mierzono przepływy wody i pobierano próbki z podłoża dna, w celu określenia granulacji jego materiału. Na podstawie zebranych wyników stwierdzono, że istnieją uzasadnione przesłanki budowy sztucznych tarlisk, głównie w Reczycy i Wardynce, gdzie panują odpowiednie warunki środowiskowe do bytowania ryb łososiowatych (dobra jakość wody), jednak ze względu na ograniczoną ilość żwirowo-kamienistego podłoża, ryby po dotarciu do górnych dopływów tych cieków nie będą mogły przystąpić do tarła.Environmental requirements of salmonids: the Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta m. trutta L.) combined with the presence of hydraulic structures on water courses significantly reduce the possibility that these valuable fish species will stay and breed in many water courses. The paper presents results of the third and final part of a research into the suitability of waters in the catchment area of the Ina River for building breeding grounds for migratory salmonid fish. The study focused on the following tributaries of the Ina River: the Wardynka, Stobnica, Reczyca, Mała Ina, Małka and Wiśniówka. Water quality in these rivers was studied during summer and the autumn-winter period in 11 sites where flow measurements were conducted, too, and samples of bottom substrate were collected in order to determine its grain size structure. On the basis of obtained results it was concluded that there were justifiable premises for building artificial breeding grounds, mainly in the rivers Reczyca and Wardynka, as they were characterized by suitable environmental conditions for salmonids (good water quality). However, due to limited areas of gravel and rocky bottom, the fish would not be able to breed after arriving at the upper reaches of these water courses