Adam Tański

Early ontogenesis of the angelfish, Pterophyllum scalare Schultze, 1823 (Cichlidae)

This study describes the egg membrane structures of angelfish (Pterophyllum scalare), morpho-physiological changes during angelfish embryogenesis from activation to hatching under optimal conditions (28°C; pH 6.8), the developing larvae and fry, the effect of alkaline pH on the early developmental stages of the species, the relationship between food item size and fry survival. Egg membranes (thin, transparent, 1.67-2.18 µm thick) are covered by a sticky substance. The amber-coloured angelfish eggs were oval in shape, with average diameters of 1.436 and 1.171 mm, i.e., a mean volume of 1.033 ± 0.095 mm3. The survival rate of embryos and larvae kept in water with an elevated, slightly alkaline pH was very low: as few as 2% of the embryos survived, while in the batch kept in optimal water conditions very few eggs died. The first larvae hatched after 1288 h of embryonic development. The newly hatched larvae measured on average 2.60 ± 0.093 mm and had large (0.64 ± 0.077 mm3) yolk sacs. They attached themselves to the substrate with a secretion of thin, viscous threads, which was released from glands situated on the top of the head. The glands vanished on day 5. The 1-day-old larvae showed the first pigment cells on the body and the eyes of the 2-day-olds were already fully pigmented. Between day 4 and 5 of larval life, the larvae began feeding on live food. The 23-day-old fry looked like a miniature versions of the adults. Mortality of the angelfish larvae during their first days after hatching was higher in those fed brine shrimp (Artemia salina) nauplii than those fed protozoans and rotifers.

The effect of magnetic field on permeability of egg shells of salmonid fishes

The embryos of fishes during their development, between the egg activation and their hatching, are exposed to action of various factors of the external environment. Those factors, while acting simultaneously, may exert higher pressure, than when acting individually. Despite the common assumption about alleged stability of the aquatic environment, its biotic and abiotic factors, affecting aquatic organisms, may be highly diversified. An individual organism is not only affected by selected, uniform environmental factors. Usually the maintenance of homeostasis is dependant on a complex system of a number of external and internal stimuli (Haas et al. 1997) The magnetic field, and the associated magnetic phenomena are so ubiquitous that they have hitherto been neglected. They attracted some more attention in recent decades and it become evident that living organisms are not indifferent for the action of the magnetic field (Wiltschko and Wiltschko 1995, Kirschvink 1997). The natural magnetic field of the earth is an integral component of the environment, in the same extent as temperature or gravitation, and it also constitutes the background for life processes on the Earth. The common nature of the magnetic field has prompted many researchers to study in detail its action on living organisms. Wadas (1978) distinguished three basic reasons why magnetic fields affect living organisms: 1) action of non-compensated electron spins, 2) action on liquid crystals, 3) effect on positiveand negative charges, being in motion. To answer the question of the action of the magnetic field on animals, many researchers observed effects of such action. Among the aspects studied was the homing ability of insects (honey bee) (Gould 1980), crustaceans (lobster)(Boles and Lohmann 2003), fishes (salmonids)(Quinn and Brannon 1982), amphibians (newt)(Phillips 1986), reptiles (turtles)(Lohmann et al. 1999), or birds (pidgeon)(Keeton 1971). The behavioral experiments focused mainly on species performing long-distance migrations, such as eels and salmonid fishes, as well as elasmobranch fishes (Mayer et al. 2005, Nishi et al. 2005). ACTA ICHTHYOLOGICA ET PISCATORIA (2007) 37 (2): 129–135 DOI: 10.3750/AIP2007.37.2.10

The effect of effluents from rainbow trout ponds on water quality in the Gowienica River / Wpływ zrzutu wód poprodukcyjnych ze stawów pstrągowych na jakość wody w rzece Gowienicy

Abstract Fish farming and especially rearing and breeding of rainbow trout and carp is one of potential sources of surface water pollution. The study was aimed at assessing the effect of a rainbow trout farm on water quality in the Gowienica River in winter. Temperature, pH, electrolytic conductivity, total suspended solids, dissolved oxygen, BOD5, CODCr, alkalinity, water hardness, calcium, magnesium, ammonium-nitrogen, nitrate-nitrogen (III and V) and total phosphorus were determined according to Polish Norms and APHA [1995] in water samples collected in winter up- and downstream the study object. The increment of pollutant concentrations in rainbow trout farm effluents was referred to the requirements in Rozporządzenie MŚ [2006]. Performed studies and literature review show that effluents from the assessed fish farm did not worsen water quality of the river. Increased concentrations of total suspended solids and CODCr in effluents were noted only in March. According to data from the report on environmental status in zachodniopomorskie province in the years 2008-2011, poor water quality of the Gowienica River is recorded already upstream the rainbow trout farm. Pollution of this stretch of the river may originate from uncontrolled waste water management and from nutrient runoff from fields. STRESZCZENIE Jednym z potencjalnych źródeł zanieczyszczenia wód powierzchniowych jest gospodarka rybacka zajmująca się głównie chowem i hodowlą pstrąga tęczowego i karpia. Celem pracy była ocena wpływu działalności gospodarstwa pstrągowego na jakość wód Gowienicy w sezonie zimowym. W okresie zimowym w pobranych próbkach wody w punktach powyżej i poniżej obiektu oznaczano następujące wskaźniki: temperaturę, pH, przewodność elektrolityczną, zawiesinę ogólną, tlen rozpuszczony w wodzie, BZT5, ChZTCr, zasadowość, twardość, wapń, magnez, azot amonowy, azot azotanowy (III) i (V), fosfor ogólny - zgodnie z wybranymi Polskimi Normami i zaleceniami APHA [1995]. Określano przyrost zanieczyszczeń w wodach poprodukcyjnych z hodowli pstrągów, który odnoszono do wymogów zawartych w Rozporządzeniu MŚ [2006]. Jak wynika z przeprowadzonych badań oraz z przeglądu literatury, wody poprodukcyjne pochodzące z działalności ocenianego gospodarstwa rybackiego nie wpływały na pogorszenie jakości wody badanej rzeki. Uzyskane w pracy wyniki wykazały przyrost stężenia zawiesin ogólnych i ChZTCr, w wodach poprodukcyjnych tylko w marcu. Zgodnie z danymi zawartymi w raportach o stanie środowiska w woj. zachodniopomorskim w latach 2008-2011, niezadowalająca jakość wód Gowienicy jest notowana już na odcinku powyżej gospodarstwa pstrągowego. Źródłem zanieczyszczeń występujących na tym odcinku Gowienicy może być nieuregulowana gospodarka kanalizacyjna w gminie, jak również spływy składników biogennych z pól.

Specifying the relationship between key stages of pike (Esox lucius L.) embryogenesis and coagulants used in lake recultivation

Abstract The study focused on the effect of iron and aluminium coagulants (PIX®113, PAX®18) commonly used for purification of open waters on key stages of embryonic development of pike (Esox lucius L.). Fertilized pike roe was incubated in lake water and in water with the admixture of coagulants, applied in the concentration of 50.0 mg dm-3 at selected stages of embryogenesis: blastopore closure, inoculation, and the hatching of larvae. In the course of the experiment, live embryos were observed and total lengths of the larvae were measured. Simultaneously, selected hydrochemical indicators were gauged. It was discovered that coagulants had the strongest effect at the first stage of embryogenesis (the end of the process of gastrulation). At that stage the survival rate of embryos was the lowest (73.5- 75.0%) and the percentage of deformities in the hatched larvae was the highest (9.7-10.0%).

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

Genus Ancistrus is represented by fish commonly known as bushymouth or bristlenose plecos. They occur in the watershed of upper Amazon including Peruvian Ucayali and less frequently in the lower Amazon watershed (Kornobis 1990). The fish of this genus living in the wild can reach up to 15 cm of length, whereas in the captivity (culture) they do not exceed 13 cm (Riehl and Baensch 1996). Adults show sexual dimorphism, the juveniles look the same despite their sex. The reproduction of bushymouth catfish, Ancistrus dolichopterus Kner, 1854, is difficult to observe because it occurs at night in shaded areas—most frequently in hiding spots. The male prepares so called “pseudo-nest” before female would lay the eggs. He carefully cleans the nest and protects it from invasion of any potential predators e.g., snails. This specific care fulfilled only by the male lasts during the entire embryonic development till the larvae leave the nest, move independently, and are able to feed themselves (Rymkiewicz 1988). ACTA ICHTHYOLOGICA ET PISCATORIA (2011) 41 (3): 223–227 DOI: 10.3750/AIP2011.41.3.10