Search results for "kalat"
showing 10 items of 190 documents
The effects of different combinations of fixed and moving bed bioreactors on rainbow trout (Oncorhynchus mykiss) growth and health, water quality and…
2019
The effect of bioreactor design on nitrification efficiency has been well studied, but less is known about the overall impacts on water quality. Besides nitrification, submerged fixed bed bioreactors (FBBR) trap fine solid particles, whereas moving bed bioreactors (MBBR) grind solids, possibly increasing solids and particle accumulation in the system. In this experiment, the effects of different combinations of fixed bed and moving bed bioreactors on water quality, solids removal, particle size distribution, fish health based on histopathological changes and nitrification efficiency were studied in laboratory scale recirculating aquaculture systems (RAS) with rainbow trout (Oncorhynchus myk…
Ultraviolet B radiation induced alterations in immune function of fish : in relation to habitat preference and disease resistance
2009
Runsas altistuminen auringolle on tunnetusti haitallista ihmisten ja eläinten hyvinvoinnille. Eveliina Markkula tutki väitöskirjatyössään, miten ultravioletti B (UVB) -säteilylle altistuminen vaikuttaa kalojen vastustuskykyyn ja tautialttiuteen.- Ilmakehän otsonikerroksen oheneminen viime vuosikymmenten aikana on johtanut UVB-säteilyn lisääntymiseen maan pinnalla. UVB-säteily tunkeutuu myös kirkkaisiin järvi- ja merivesiin ja voi näin aiheuttaa haittaa kaloille, Markkula kertoo.UVB-säteilyn on jo aiemmin todettu lisäävän kalojen varhaisten elinvaiheiden epämuodostumia ja kuolleisuutta. Kertaluonteinenkin altistuminen lampuilla tuotetulle UVB-säteilylle aiheuttaa muutoksia kalan immuunijärje…
Gill area explains deviations from body size–metabolic rate relationship in teleost fishes
2022
Whether gill area constrains fish metabolism through oxygen limitation is a debated topic. Here, the authors provide insights into this question by analysing mass-specific metabolic rates across 44 teleost fishes extracted from FishBase. They explore whether species deviations from metabolic rates predicted by body mass can be explained by species gill area. They show that the gill area explains c. 26%–28% of species-level deviations from mass-specific metabolic rates. Their findings suggest that gill area might indeed be one of the factors limiting metabolic rate in fishes.
Studies of the life history of a parasite : a basis for effective population management
2005
Kalatäit ovat pintaloisia, jotka imevät kaloista verta. Ne liikkuvat kalan pinnalla ja vaurioittavat ihon pintaa. Ihovauriot ja niistä johtuvat bakteeri- ja sienitaudit heikentävät kalojen arvoa ja voivat johtaa kasvun hidastumiseen ja kalan kuolemaan. Kalatäiden torjunta kalanviljelylaitoksissa on ollut vaikeaa ja tehotonta, koska niiden ekologiaa ja elinvaiheita ei ole tunnettu, kertoo Teija Hakalahti. Hakalahti tutki Argulus coregoni -kalatäin ekologiaa ja käyttäytymistä loisen elinkierron eri vaiheissa, joita ovat munat, munista kuoriutuvat vapaana elävät nuoruusvaiheet ja kalassa aikuistuvat loiset. In this thesis, the life history traits of the ectoparasite Argulus coregoni were exami…
Pulsed flow-through cultivation of Margaritifera margaritifera : effects of water source and food quantity on the survival and growth of juveniles
2020
AbstractConservation of the endangered freshwater pearl mussel (FPM) includes artificially rearing juveniles, but the pulsed flow-through (PFT) method, enabling the continuous renewal of water and food in culture containers, has not been applied to FPM. This study tested the PFT method in culture of FPM juveniles, and the effect of water source (tap vs well water) and food concentration (mixture of commercial phytoplankton products) on the survival and growth of juveniles. Beaker-specific survival rates varied from 0 to 100% (mean: 34%) and from 0 to 58% (mean: 16%) in the 1st (2-week) and 2nd (10-week) experiment, respectively. In the 1st experiment, juveniles attained statistically signif…
Comparison of migratory and resident populations of brown trout reveals candidate genes for migration tendency
2018
Candidate genes associated with migration have been identified in multiple taxa: including salmonids, many of whom perform migrations requiring a series of physiological changes associated with the freshwater–saltwater transition. We screened over 5,500 SNPs for signatures of selection related to migratory behavior of brown trout Salmo trutta by focusing on ten differentially migrating freshwater populations from two watersheds (the Koutajoki and the Oulujoki). We found eight outlier SNPs potentially associated with migratory versus resident life history using multiple (≥3) outlier detection approaches. Comparison of three migratory versus resident population pairs in the Koutajoki watershe…
Assessment of fish migration in rivers by horizontal echo sounding : problems concerning side-aspect target strength
2004
Liljan tutkimus osoittaa, että sivuttaissuuntaisella kaikuluotauksella pystytään hyvin havaitsemaan vastavirtaan uivat kalat. Kalan koon määrittäminen sekä lajien erottaminen toisistaan monilajisessa kalayhteisössä ei ole kuitenkaan mahdollista tarkastelemalla pelkästään heijastunutta kaikua. Liljan mukaan kaikuluotaustutkimuksiin onkin syytä yhdistää koekalastukset aina, kun läsnä on tutkittavan lajin lisäksi muita kalalajeja.Kiinteästi paikalleen asetettuja lohkokeilakaikuluotaimia on käytetty jokeen nousevien emolohien lukumäärän arvioinnissa 1990-luvun vaihteesta lähtien. Menetelmässä kalat läpäisevät kaikuluotaimen lähettämän äänikeilan aktiivisesti uimalla ja tulevat näin rekisteröidy…
Lipid-related thiamine deficiency cause mortality of river lampreys (Lampetra fluviatilis) during pre-spawning fasting
2023
Publisher Copyright: © 2023 The Authors River lampreys (Lampetra fluviatilis) were caught in the fall 2014 on entering the River Perhonjoki for spawning and kept at a hatchery until spawning in late spring 2015 to produce larvae for compensatory stockings. Since the lampreys died massively from early February onwards, they were investigated in March and May to clarify the cause of the deaths. The symptoms in lampreys resembled those of lipid-related thiamine (vitamin B1) deficiency of salmonines, called the M74 syndrome in the Baltic Sea area. Because the lipid content of lampreys was known to be high, thiamine concentrations were analyzed in the liver and ovulated unfertilized eggs, and th…
Toxicity of retene and pyrene on fish at different light conditions
2011
Rearing background and exposure environment together explain higher survival of aquaculture fish during a bacterial outbreak
2019
1.Parasitic diseases represent one of the greatest challenges for aquaculture worldwide and there is an increasing emphasis on ecological solutions to prevent infections. One proposed solution is enriched rearing, where traditional stimulus‐poor rearing tanks are equipped with different types of structures to increase habitat complexity. Such spatial enrichment is known to increase survival of fish during parasite epidemics, but the underlying mechanisms are still unclear. 2.We studied whether enriched rearing affected infection of an important fish pathogen Flavobacterium columnare in young Atlantic salmon (Salmo salar) and sea‐migrating brown trout (Salmo trutta). First, we used natural b…