Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 50

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Background. The hitherto published records of the parasite fauna of Baltic cod, Gadus morhua callarias cover commercially-caught adult fish. The aim of this study was to determine the composition of the parasite fauna of young Baltic cod, the relevant infection parameters and to relate those data to published records on the diet of cod. Materials and Methods. This survey was carried out on 154 young cod, caught in May and June 2002 in the Gulf of Puck, the Baltic Sea, Poland. The fish were examined using standard methods applied in parasitology. Results. No external parasites were found. In the digestive tracts of 58 cod, 3 species of parasites belonging to 2 higher taxa (Nematoda and Acanthocephala) were found. The dominant parasite was Echinorhynchus gadi Zoega in Müller, 1776. The mean abundance ranged from 0.15 to 2.75. The prevalence ranged from 14.6%, in the smallest fish, to 66.7% in the larger ones. Only two acanthocephalan specimens of Pomphorhynchus laevis (Zoega in Müller, 1776) and five nematode larvae of Hysterothylacium aduncum (Rudolphi, 1802) were found. Conclusion. The parasite fauna of young Baltic cod is significantly sparser than in larger fish examined by other authors. It is suggested that the occurrence of the species found, can be related to the composition of diet available.
The study focused on the eel (length and weight averaging 23.1 cm and 13.7 g, respectively) ascending Pomeranian rivers in summers of 1999-2003. The swim bladder was examined in 322 individuals, the intestine being examined in 272 fish. Anguillicola crassus was present in the swim bladder of 184 fish. Infection prevalence varied between the rivers, the highest prevalence being recorded in the eel caught in the Radew (65.6%) and the lowest in the Wieprza (41.7%). The intensity of infection was generally low, the mean values varying from 2. l in the Rega to 1.3 in the Wieprza. The coefficient of infection was low (0,11 to 0,12). Spinitectus-inermis was present, with low intensity, in the intestine of 18 fish (6.6%). The nematode had not been recorded in the eel in Poland for 70 years. In addition, the intestine of the eel under study was found to house Raphidascaris acus and Paraquimperia tennerima, each present as a single larva. This is the first record of the latter in Poland. The infection of eel from the Radew river that stayed in the fresh water for a longer time was higher than that of the eel found in the Rega and Wieprza.
Background. Monogenean parasites Pseudodactylogyrus anguillae and P.bini were for the first time recorded on eel in 1995. The aim of the present study was to determine their distribution in Poland and to verify their measurements against literature data. Materials and Methods. A total of 201 young eels ascending rivers of Polish Western Pomerania, emptying to the Baltic Sea, were collected and necropsied using commonly used methods. Results. Altogether, 574 monogeneans were found on the gills of the eels studied, of which P. anguillae constituted 82%. Measurements of hard elements of the two species of parasites were similar to those already described from Poland. Conclusion. The present paper constitutes a new record of Pseudodactylogyrus anguillae and P. bini, supported by measurements.
Sinanodonta woodiana (Lea, 1834) is an alien species in the fauna of Poland. It comes from the catchment area of the rivers Amur and Yangtze. In Poland it was found in the early 1980s in the system of heated lakes near Konin (Kujawy Lake District, C-Poland). It appeared there together with the silver carp Hypophthalmichthys molitrix (Valenciennes, 1884) and big-heated carp Aristichthys nobilis (Richardson, 1845) introduced from Hungary. In 2003 it was found in the release channel of cooling water from the Dolna Odra power plant. In the years 2004-2005 an inventory of the Międzyodrze (N-W Poland) channels was made in order to determine the current range of occurrence of S. woodiana in the Western Pomerania Region. The mussels were found at five localities below the release of the cooling water. The channels are partly frozen in winter, which indicated the adaptation abilities of this species to waters typical of temperate zone. In the outer demibranch marsupia of females the presence of glochidia was detected, which pointed to the readiness of the mussels for reproduction.
Background. The pumpkinseed, Lepomis gibbosus (Linnaeus, 1758), known also as pumpkinseed sunfish, is native to eastern and central North America. Its introduction to Europe has resulted in fast spreading of the species over the continent. In Poland, the pumpkinseed has found favourable conditions for living and reproduction in water bodies artificially heated by thermal power plants. The aim of this study was to determine the annual cycle of gonad development of the pumpkinseed population inhabiting the warm-water canal of the Dolna Odra power plant (NW Poland), which has not been studied before at this location. Materials and Methods. The pumpkinseed individuals were caught in the heated-water discharge canal of the Dolna Odra power plant. The average water temperature in the canal was by 6–8ºC higher than that of the river. The analysis of the annual cycle of gonad development was performed in both sexes using histological methods. The fish were aged 3+ to 6+. A standard paraffin technique and Heidenhain’s iron hematoxylin staining were used. Results. In the site surveyed, the spawning season for females lasted from the beginning of May through August, i.e., was longer than in the native range of this fish species. In one female caught in September, the ovaries contained oocytes in the stage of vitellogenesis. The oocytes in the stage of atresia were found rarely in the fish caught from April through June. Mature testes in males were found between late April and September, i.e., throughout the spawning period of the females. Few male anomalies of the sexual cycle were observed, e.g., in October, they were found to engage in another cycle of spermatogenesis and spermatozoa production. Moreover, the presence of large groups of degenerating cells in the seminal tubules was observed throughout the year, but was particularly evident between September and February. Conclusion. The results have confirmed the high colonisation abilities of the pumpkinseed. As a consequence of global warming, the studied canal with post-cooling water may become a starting point of expansion of this species to other bodies of water. Upon a considerable climate warming, this species could threaten the native species.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.