Piotr Hliwa

Reproductive parameters of common carp (Cyprinus carpio L) spawners during natural season and out-of-season spawning

Common carp spawning characteristics were compared between season and out-of-season periods. There were no differences in the percentage of ovulation, spermatozoa motility and embryo survival to the eyed-egg-stage between the spawning periods. Fish spawned during the season produced oocytes of higher total weight than those spawned out-of-season. On the day exogenous feeding began, larvae obtained in out-of-season spawning were shorter than those obtained during the spawning season. However, the out-of-season larvae started feeding two days earlier than in-season larvae. As a result, seven days after fertilization, larvae obtained during out-of-season had the same length as larvae obtained during season. It appears to be possible to obtain common carp larvae half a year before the natural spawning period without decreasing the quality of gametes and larvae.

Food web manipulation in a small, eutrophic Lake Wirbel, Poland: effect of stocking with juvenile pike on planktivorous fish

In a four year experiment (1988–1991) carried out in a shallow, eutrophic lake, an increase in young-of-the-year pike (Esox lucius) density was used to control planktivorous fish assemblages consisting mainly of small-sized cyprinids: roach (Rutilus rutilus), Leucaspius delineatus, and white bream (Blicca bjoerkna). Stocking with pike fry of ca 30 mm in three successive springs resulted in large-scale mortality among prey of vulnerable sizes. Rotenone treatment at the end of the fourth year showed that roach and white bream populations contained few 0+ to 2+ fish, but very high numbers of 3+ to 6+ fish. By this time, short-lived, slow-growing L. delineatus, with no size refuge from predators, had been driven almost to extinction.

Isolation and characterization of transferrin from common carp (Cyprinus carpio L) seminal plasma.

Transferrin (Tf) in fish is recognized as a component of non-specific humoral defense mechanisms against bacteria. It is a major protein of common carp seminal plasma but its structure and localization in carp testis is unknown. In this study we developed a simple and efficient three-step purification procedure consisting of affinity chromatography (Con A-Sepharose), hydrophobic interaction chromatography (Phenyl Sepharose) and gel filtration (Superdex 200). The molecular mass of Tf has been determined to be 73.6 kDa and isoelectric point 5.1. The peculiar characteristics of carp transferrin were the lack of carbohydrate component and binding of iron ions by only one functional iron-binding site. Western blot analysis revealed a strong similarity of carp seminal plasma Tf to carp blood Tf and Tf from seminal plasma of other cyprinids but a lower similarity to salmonid and percid fishes. Tf was localized to the blood vessels of the carp testis which strongly suggest that most Tf of carp seminal plasma originates from blood. In conclusion, seminal plasma Tf has a unique structure and is similar or identical to blood Tf.

Carp transferrin can protect spermatozoa against toxic effects of cadmium ions.

Cadmium is a widespread heavy metal that enters the aquatic environment and affects many processes involved in fish reproduction such as sperm motility. Fish seminal plasma proteins can protect spermatozoa against toxic effects of heavy metals. The objective of this study was to demonstrate the ability of a major carp seminal plasma protein-transferrin (TF) to bind cadmium ions and to neutralize the toxic effect of cadmium on carp sperm motility. To obtain a high quantity of carp seminal plasma TF necessary for the experiment, immunoaffinity chromatography as a one-step isolation procedure was established. The titration of TF with cadmium ions spectrophotometrically at 247nm revealed that TF binds cadmium ions at only one spectrophotometrically-sensitive binding site, which suggests that TF is capable of neutralizing the cadmium toxic effect. Indeed, the addition of carp TF to carp semen incubated with 50ppm cadmium for 48h led to about a four-times higher percentage of sperm motility (30.3±1.1%) in comparison to samples incubated with only 50ppm cadmium (8.2±5.2%). Similarly, higher values of other parameters of sperm movement measured by a computer-assisted sperm motility analysis system (VSL, VCL and ALH) were observed at the presence of transferrin. In conclusion, our study provides the first evidence that transferrin from carp seminal plasma can protect sperm motility from cadmium toxicity.

Food-web manipulation in a small, eutrophic Lake Wirbel, Poland: long-term changes in fish biomass and basic measures of water quality. A case study

A whole-lake experiment was carried out for seven years(1988–1994) in a shallow, eutrophic lake. In the first phase(1989–1991), repeated introductions of young-of-the-year pike(Esox lucius) were used to control the density ofjuvenilestages of the dominant planktivores (roach Rutilusrutilus,white bream Blicca bjoerkna and Leucaspiusdelineatus).The successive introductions of juvenile pike were accompaniedbyselective removal of large pike, roach, bream Abramisbramaand white bream. No visible improvement in water quality wasregistered in the first three years. Assessments made afterthelake was treated with rotenone, revealed the high efficiencyofjuvenile pike in controlling prey of vulnerable size. Thoughthefirst three age-classes were nearly exterminated, older fish(3+ to6+) remained abundant enough to keep their planktonic prey incheck. Indeed, the non-altered density of dominant cladoceransindicated that they were still heavily preyed upon. Algalbiomassremained high.In October 1991, rotenone was applied to remove all fish.Immigrating fish were gradually recolonizing the lake fromspring1992 onwards. However, the process was kept under control bycontinued stocking with juvenile pike and intensive fishing.Theyears following the rotenone treatment witnessed aconsiderableimprovement in water quality, with water transparency 30%higher,a significant 2.2-fold decrease in seston dry weight and2.8-folddecrease in algal biomass, averaged for the summer months.Theseevents can largely be attributed to substantial changes in theherbivorous zooplankton, above all increased density of LakeWirbels largest cladoceran, Daphniacucullata.

Changes in sperm parameters of sex-reversed female rainbow trout during spawning season in relation to sperm parameters of normal males

The production of all-female populations has important economic benefits in commercial rainbow trout aquaculture. The procedure commonly implemented to produce all-female stocks centers on the sex reversal of rainbow trout females via the administration of androgens in the early developmental stages, followed by the egg fertilization of normal females with semen from sex-reversed females (srf). However, there is no information regarding the quality of semen from srf rainbow trout throughout the spawning season. This information is critical because the quality of srf semen is highly variable. The aim of the study was to determine the changes in the semen parameters of srf rainbow trout throughout the duration of the spawning season. Sperm concentration, sperm motility parameters, and the biochemical parameters of seminal plasma (protein concentration, antitrypsin activity, osmolality, and lactate dehydrogenase activity) from srf were monitored during the spawning season and compared with normal male rainbow trout. The observed values of sperm, protein concentration, antitrypsin activity, osmolality, and lactate dehydrogenase activity of seminal plasma were all higher in comparison with normal males. Semen from srf was therefore characterized by a lower sperm motility during each period of the spawning season, in comparison with normal males, approximately 1.8, 1.5, and 1.7 times, respectively for the beginning, middle, and end of the spawning season. The percentage of sperm motility from srf and normal males were affected by the spawning season in the same way, as the highest values in the middle of the spawning season demonstrate (60% and 91% for srf and normal males, respectively). Spermatozoa of srf are characterized by a lower speed and a more curvilinear trajectory of movement as compared with that of normal males. The patterns of changes during the spawning season in sperm concentration, sperm motility parameters, as well as osmolality, and lactate dehydrogenase activity of the seminal plasma of srf were different in comparison with normal males. Our results could be important for fish breeders in regard to the spawning control of srf rainbow trout, as well as for the development of short- and long-term sperm storage procedures.

Biochemical and physiological characteristics of semen of sex-reversed female rainbow trout (Oncorhynchus mykiss, Walbaum)

This works studies the biochemical (protein concentration, osmolality, antitrypsin activity, lactate dehydrogenase activity) and physiological characteristics (sperm motility characteristics) of semen of sex-reversed female rainbow trout (n=42) obtained with the application of 11β-hydroksyandrostendione for sex reversal. All data were arbitrarily divided into three classes depending on the percentage of sperm motility: I XX<25%; II XX 25-50% and III XX>50%. The average percentage of sperm motility was 18±7% n=12 (group I XX); 42±6% n=15 (group II XX) and 65±12% n=15 for group III XX, respectively) to link the values of semen parameters to the maturation stage of semen. Semen from 12 normal males of the same age was used as a reference group. Sperm concentration as well as protein concentration, osmolality, antitrypsin activity, and lactate dehydrogenase activity in seminal plasma of sex-reversed females were higher compared with the values obtained for normal male rainbow trout. The values of these parameters declined with the increasing percentage of sperm motility toward values established for normal males. The fertilization success of semen (3×10(6) spermatozoa/egg) of sex-reversed females was very high (above 90%) for both the percentage of eyed embryos and hatched larvae and was related to sperm motility classes. Correlations between the quality parameters of sex-reversed females semen corresponded to those established previously for the semen of normal male rainbow trout. Antitrypsin activity, lactate dehydrogenase, protein concentration, and osmolality were found to be characteristic of seminal plasma of sex-reversed females. The maturity of sex-reversed female spermatozoa seems to be associated with the decline in the values of those parameters toward the values characteristic for seminal plasma of normal males.

Quality and quantity of smelt (Osmerus eperlanus L.) sperm in relation to time after hormonal stimulation

The effect of Ovaprim (salmon GnRH analogue and a dopamine antagonist) treatment on the quantity and quality of smelt (Osmerus eperlanus L.) sperm was studied in relation to time after hormonal stimulation. Sperm was obtained at 0, 24, 48 and 72 h after treatment (n=13/each time point). Computer Assisted Sperm Analysis (CASA) was used to evaluate sperm motility parameters and histological analysis was used to examine the testis morphology. Only a small volume of semen (1-5 µl) was collected at the beginning of the experiment (time 0) but it dramatically increased 24 h after hormonal treatment. A further increase in semen volume was recorded 48 h after hormonal stimulation. CASA parameters, such as percentage of motile cells, progressive motility, curvilinear velocity, straightlinear velocity, straightness and amplitude of lateral head displacement of stripped sperm increased 48 h after hormonal treatment, which indicates high quality of sperm. No further increase in sperm quality was recorded at 72 h. Compared to stripped semen, testicular semen was characterized by a slightly lower quality. In addition, histological analysis indicated that 24 h after hormonal treatment, a high number of spermatozoa was released from the testis. Ovaprim-stimulated smelt became clearly darker than the control fish. In conclusion, our results suggest that smelt semen should be collected 48 h after hormonal stimulation to ensure high quality of semen. This time may vary depending on maturation status of testis.

Characterization and cryopreservation of whitefish ( Coregonus lavaretus L.) semen from Lake Łebsko, Poland

Experiments were performed to establish an efficient cryopreservation method for whitefish semen from Lake Lebsko. Semen was collected from native spawners in Lake Lebsko during two consecutive spawning seasons, 2006 and 2007. The semen collected in 2006 was of poor quality. A cryopreservation method was developed for both gonadal and stripped semen using methanol as a cryoprotectant and the French straws method. The results are important for the development of methods to improve the control of whitefish reproduction. Quality control of semen and cryopreservation must be integrated into fish conservation efforts, especially with regard to stocking.

Gyrodactylus proterorhini Ergens, 1967 (Monogenoidea, Gyrodactylidae) in gobiids from the Vistula River—the first record of the parasite in Poland

During a parasitological survey of two non-native fish species—racer goby Neogobius gymnotrachelus and monkey goby Neogobius fluviatilis—in the Włocławek Reservoir on the lower Vistula River, the monogenean Gyrodactylus proterorhini was recorded for the first time in Poland, and for the first time, the racer goby was listed as the parasite host. Specimens of G. proterorhini were detected on body surface, fins, and gills of the fish studied. In 2006, the monkey goby was infected with the prevalence 41%, racer goby with the prevalence of 47%, at maximal intensity of 6 and 9 parasites per fish, (respectively). The infection level in relation to the fish size and sampling season was also discussed. The presented study supports the hypothesis of progressive introduction of the parasite with gobiids to the colonized areas.