Respiratory movements of trout (Salmo trutta L.) larvae during exposure to magnetic field

The effect of steady magnetic field on movement velocity of pectoral fins in trout (Salmo trutta L.) larvae was determined. Newly hatched trout larvae were exposed to magnetic field (51-70 mT). Steady magnetic field was found to cause an increase in movement velocity of pectoral fins of larvae. The number of movements increased significantly until the 6th min after magnetic field application, whereupon - beginning from the 9th min - it gradually dropped

Activation and motility of spermatozoa of vendace (Coregonus albula L.)

The number of activated spermatozoa of vendace (Coregonus albula L.) and their motility under natural conditions at the fishing ground were determined. The percentage of spermatozoa activated upon contact with water was found to be relatively high, and motility period (turbulent and smooth phase of progressive movement, and oscillatory movement) - fairy long, i.e. exceeding 2 min

A device for transporting fish gametes and fertilised eggs in a magnetic field

A device for transporting and storage of fish gametes, developing eggs, and newly hatched fry in a constant, adjustable (3-9 mT) magnetic field was constructed. The device has a relatively large, thermally insulated, biological material storage compartment, exposed to highly uniform (± 2.5%) magnetic field

Effects of constant magnetic fields on respiration of rainbow trout (Oncorhynchus mykiss Walb.) embryos

Oxygen uptake and carbon dioxide release by rainbow trout (Oncorhynchus mykiss Walb.) embryos exposed to constant magnetic fields of 5 and 10 mT (oxygen uptake and carbon dioxide release) and 50, 150, and 300 mT (oxygen uptake) were measured. The data were compared with those recorded in embryos developing under natural magnetic field (control). The magnetic fields tested were found to stimulate respiratory processes in the rainbow trout embryos as shown by a significantly increased oxygen consumption, particularly during periods of intensified morphogenesis. Exposure to 5 and 10 mT magnetic fields resulted in a slightly higher carbon dioxide release, the oxygen consumption being observed to increase as well. The respiratory quotient of the embryos exposed to magnetic fields was slightly higher than that in the control

Water uptake by trout (Salmo trutta L.) eggs exposed after activation to magnetic field

Study was made of the effect of steady magnetic field (200-250 mT) on water absorption of eggs of trout (Salmo trutta L.). It was found that eggs exposed to magnetic field absorbed water in the initial period of activation (until 30 min) much slower than control eggs. Subsequently water absorption was accelerated to such an extent that after complete formation of the perivitelline space the volumes of the treated and control eggs were the same. The authors interpret the change in water absorption dynamics in terms of a reduction of the permeability of egg membrane, resulting from the effect of magnetic field on liquid crystal making part of its structure

Size of eggs and duration of embryogenesis in fishes

Studies were undertaken on the relationship between egg size and duration of embryogenesis in four freshwater fish species (Salmo trutta L, Esox lucius L., Gasterosteus aculeatus L., Leucaspius delineatus Heck.). Analyses were carried out in a comparative sense (different taxa) as well as with respect to eggs of the same species, or even laid by the same female. In addition to understandable differences of egg size between particular species, considerable differences were observed as regards egg size in fish of the same species, and even originating from the same female. In extreme cases the differences in egg size of the same female reached up to 11 percentage points (linear size) and over 40 (volume)! A strict relationship was found between duration of embryonic development and egg size: the smaller the egg, the shorter its embryogenesis. Biological meaning of this phenomenon has been discussed

Spatial orientation of trout (Salmo trutta L.) and rainbow trout (Oncorhynchus mykiss Walb.) embryos in natural and artificial magnetic fields

Trout (Salmo trutta L.) and rainbow trout (Oncorhynchus mykiss Walb.) embryos developing in eggs incubated in the geomagnetic field are oriented NW-SE. Artificial horizontal magnetic fields of 0.5 and 1.0 mT, i.e., higher than that of the natural one but of the same direction resulted in a changed alignment of the embryos examined. The embryos placed in those artificial fields were aligned N-S and NE-SW. A 90° clockwise rotation of the artificial horizontal magnetic field poles, relative to the geomagnetic one, resulted in embryos′ orientation being changed to N-S and NE-SW

The effect of water salinity on the motility of spermatozoa of the brook trout, Salvelinus fontinalis (Actinopterygii: Salmoniformes: Salmonidae)

Background. Salmonid spermatozoa are characterised by a very short time of activity in the water, therefore sudden water pollution in the form of increased salinity on the spawning grounds may have a negative effect on the sperm motility parameters, thus affecting the subsequent egg fertilisation and, consequently, the number of hatched individuals of the species. The aim of this study was to determine the effect of water salinity on the motility parameters of spermatozoa of brook trout, Salvelinus fontinalis (Mitchill, 1814). Materials and methods. Sperm motility was monitored with a camera (Basler A312fc) coupled with Nikon Eclipse 50i light microscope from the moment of their activation (contact with water) until the cessation of movement. The following water-salinity treatments were tested: 1.0‰, 3.0‰, 5.0‰, and 10.0‰. The motility parameters: VCL, VSL, VAP, ALH, BCF, LIN, STR, WOB, and MOT, were analysed with Computer Assisted Sperm Analysis (CASA). Results. The mean values of the studied motility parameters of the brook trout spermatozoa (obtained within 30 s), whose activation took place in the water of 0.35‰ salinity and in water of 1.0‰ and 3.0‰ salinity, did not differ significantly. The highest mean values of motility parameters were recorded for the water of 5.0‰ salinity.  The 10.0‰ treatment caused a distinct decrease in the values of all the studied parameters. The percentage of MOT was the highest (37.5%) in the sample activated in the water used for fish rearing (0.35‰). In the remaining samples the MOT was lower, and in the water of 10.0‰ salinity it was only 9.1%. No spermatozoa movement of any kind was recorded in the 35th second of the experiment. Conclusion. The values of the motility parameters as well as the percentage of motile spermatozoa (MOT) in the semen decrease with increasing salinity of the water used for activation, and with increasing time of exposure