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Η ΒΥΠ διαθέτει αντίτυπο της διατριβής σε έντυπη μορφή στο βιβλιοστάσιο διδακτορικών διατριβών που βρίσκεται στο ισόγειο του κτιρίου της. / Το σύστημα του συμπληρώματος περιλαμβάνει πάνω από 30 πρωτεΐνες του πλάσματος (διαλυτές και υποδοχείς) και παίζει σημαντικό ρόλο, τόσο στη φυσική όσο και στην προσαρμοστική ανοσία. Το συμπλήρωμα ενεργοποιείται μέσω τριών οδών, της κλασσικής, της εναλλακτικής και της λεκτινικής, καταλήγοντας σε κάθε περίπτωση, μέσω της λυτικής οδού, στη διαμόρφωση ενός τελικού συμπλόκου, που λύει το παθογόνο. Τα συστατικά του συμπληρώματος τα οποία απαρτίζουν το τελικό σύμπλοκο MAC, και συμμετέχουν έτσι στη λυτική οδό, είναι τα C5b, C6, C7, C8α, C8β, C8γ και C9. Προκειμένου να μελετήσουμε την μοριακή εξέλιξη της λυτικής οδού του συμπληρώματος κλωνοποιήσαμε και χαρακτηρίσαμε την α και γ υπομονάδα του όγδοου συστατικού του συμπληρώματος στην ιριδίζουσα πέστροφα. Τα cDNA που προέκυψαν για τα C8α και C8γ ήταν 2.037 και 977 νουκλεοτίδια, αντίστοιχα, ενώ η συναγόμενη αμινοξική αλληλουχία ήταν 615 και 221 αμινοξέα, αντίστοιχα. Τα δύο μόρια παρόλο που αλληλεπιδρούν άμεσα και δευσμεύονται επι του συμπλόκου MAC, ανήκουν σε διαφορετικές πρωτεϊνικές οικογένειες. Η μοριακές τους δομές ομοιάζουν με τις αντίστοιχες των μορίων των θηλαστικών και οι αμινοξικές τους αλληλουχίες παρουσιάζουν σημαντικό βαθμό συντήρησης. Στην πέστροφα, το C8α δείχνει να εκφράζεται κύρια στο ήπαρ και στο νεφρό, ενώ το C8γ εκφράζεται επιπλέον και στον ιστό της καρδιάς και της σπλήνας. Ανάλυση κατά Southern έδειξε πως τα δύο γονίδια συναντώνται ως μοναδικά αντίγραφα στο γονιδίωμα της ιριδίζουσας πέστροφας. Αξίζει, τέλος, να σημειωθεί οτι αυτή είναι η πρώτη αναφορά για την κλωνοποίηση της α και γ υπομονάδας του όγδοου συστατικού του συμπληρώματος στα κατώτερα σπονδυλωτά. / The complement system consists of 30 and more proteins present in blood and cell membranes and plays an important role in host defense by interacting with components of both innate and adaptive immunity. It is activated through three distinct activation pathways: the antibody-dependent classical pathway and the alternative and lectin pathways, which are activated by direct binding of complement components to microbial surfaces. Unlike mammalian and other species, teleost are the only organisms that reveal a completely developed and extended complement system, via gene duplication and functional diversity. Complement activation via the classical, lectin, or alternative pathway leads to the formation of the (pore forming) membrane attack complex (MAC) on the surface of complement-opsonized cells. The assembly of MAC involves the aggregation of the lytic complement components C5b, C6, C7, C8α, C8β, C8γ, and C9. In order to elucidate the phylogeny of the lytic pathway of complement we now report the cloning and characterization of the C8α and C8γ genes in rainbow trout (Oncorhynchus mykiss). The deduced amino acid sequence of the trout C8α gene exhibits 44 and 43% identity with human and frog orthologs, respectively. The domain architecture of the trout C8α resembles that of mammalian orthologs, and the cysteine backbone shows a high degree of conservation. The trout C8α shows a similar expression profile with that of trout C8β and C8γ, pointing to the liver as the main source of the C8α gene expression. Although the presence of a fully developed lytic pathway of complement system is expected in teleost, this is the first report of the C8α gene in an organism other than mammalian. The deduced amino acid sequence of trout C8γ shows significant identity (37%) to the human C8γ homolog and much lower to the other known lipocalins. The lipocalin domain is present and all the cysteine residues are conserved. The trout C8γ gene is probably present as a single copy in the trout genome showing a differential expression pattern among tissues investigated. This is the first report the C8α and C8γ genes in an organism other than mammalian.

Model organisms are often used in ecotoxicological studies and environmental risk assessments; however, species differences in responses to toxicants exist. A meta-analysis identified normal biomarker ranges for rainbow trout (RT) and brook trout (BT), and showed that RT had greater whole-body lipids and plasma T4 levels than BT. Exposure to selenium inhibited cortisol secretion of trout adrenocortical cells; however, RT were more sensitive than BT. To investigate species vulnerability at the individual level, RT and BT were stocked into reference and selenium-contaminated pit lakes. Fish accumulated more Se from selenium-contaminated than reference lakes, and selenium accumulation was similar between species. Chronic selenium exposure had a greater energetic cost for RT than BT, but this was mitigated by food availability. Chronic selenium exposure decreased plasma T3 and T4 levels, but did not alter other endocrine or oxidative stress biomarkers. This project highlights the need for both species- and site-specific risk assessments. / xiv, 171 leaves : ill., maps ; 29 cm

The aquatic environment is severely impacted by xenobiotics that are released due to anthropogenic activities, threatening ecosystem health. Some of these contaminants accumulate in lipophilic fish tissues and are maternally transferred to developing offspring, affecting their growth and performance. However, knowledge about the long-term and generational impacts associated with maternal transfer of contaminants is limited in fish. In this thesis, the hypothesis tested was that maternal transfer of bisphenol A (BPA) leads to disruption in the developmental programing of growth and stress axes functioning in rainbow trout (Oncorhynchus mykiss), and that these changes are passed on to the next generation. This was tested by exposing oocytes to either control (vehicle; <0.01% ethanol) 0.3, 3.0, and 30.0 mg l-1 BPA in ovarian fluid for 3 h, prior to fertilization, to mimic maternal transfer. This led to the accumulation of 0, 0.8, 4.4 and 41.3 ng BPA embryo-1. Oocytes were fertilized with milt from clean males, and offspring growth, development and stress performances were assessed in a clean environment for a year (F1 generation). For F2 generation, oocytes collected from F1 females, raised from the different BPA accumulated eggs, were fertilized with milt from clean males and raised in a clean environment for one year as described for F1 generation. The accumulated BPA in eggs was quickly cleared and it was no longer detected in the F1 embryos at hatch. BPA exposure reduced specific growth rate and increased food conversion ratio in larvae reared from BPA-laden oocytes. Moreover, BPA-exposed fish had an altered cortisol developmental profile and a delay in stress axis maturation. In addition, the mRNA abundance of genes involved in somatotropic [insulin-like growth factor (IGF) -1; IGF-2; IGF receptor b (IGF-1rb)] and stress axes functioning [steroidogenic acute regulatory protein (StAR); cytochrome P450 side chain cleavage (P450scc)] were altered. Also, changes in thyroid signaling [thyroid receptor (TR) mRNA levels] and cortisol signaling [glucocorticoid receptor (GR) protein expression] were disrupted temporally during development. These results demonstrate that BPA accumulation in eggs, mimicking maternal transfer, impacts growth and development, and delays stress axis maturation via non-reproductive endocrine disrupting routes in trout. Some of the BPA changes seen in F1 generation also persisted in the F2 generation. For instance, ancestral exposure to BPA led to reduced growth and whole body glycogen content prior to feeding in the F2 fish. The developmental transcript profile of growth hormone-1and -2, IGF-1 and -2 and IGF-1rb, along with whole body cortisol levels were impacted by ancestral exposure to BPA. Moreover, a delay in cortisol dynamics post-stress was noted in the F2 fish of BPA exposure lineage. Our results show that ancestral exposure to BPA leads to effects on growth and stress performance in rainbow trout, but the mechanism is not known. To further investigate the long-term effect of BPA accumulation in eggs on stress performances, F1 and F2 juvenile fish were subjected to an acute stressor. Also, head kidney tissues from these juvenile fish were subjected to adrenocorticotrophic hormone (ACTH) stimulation in vitro to assess cortisol production capacity. BPA accumulation in eggs led to a reduced acute handling stressor-induced plasma cortisol response in trout from the F1 and F2 (only high BPA group) generations. Also, BPA exposure had a pronounced impact on acute handling stressor-mediated plasma glucose (only F2 generation) and lactate levels, indicative of a metabolic disturbance. BPA exposure (only the 4.4 ng group) did affect unstimulated but not stimulated [ACTH or 8-bromo-cyclic AMP (8-B-cAMP)] cortisol production from head kidney slices of juvenile fish from F1 generation. In the F2 generation, there was an increase in ACTH-stimulated cortisol production only from the high BPA-exposed group. Overall, BPA in eggs disrupts long-term cortisol and metabolic stress performances in rainbow trout. While the impaired plasma cortisol stress performance was dose-related in the F1, the effect was apparent only for high BPA group in the F2 generation, suggesting that the generational effects on cortisol stress axis functioning may be concentration-dependent. A metabolomics approach further confirmed multigenerational effects associated with BPA accumulation in eggs. Analysis of the metabolome profile at hatch and prior to first feed, using gas chromatography-time of flight-mass spectrometry (GC-TOF-MS), revealed a BPA-mediated metabolic disruption, including changes in pathways involved in carbohydrate, lipid and amino sugar metabolism, and amino acid metabolism and synthesis. Pathways involved in citric acid cycle and alanine, aspartate and glutamate metabolism were altered in both generations, suggesting that these pathways have the potential to be markers with predictive value for multigenerational effects of BPA in fish. Altogether, the study provides novel insights on the impact of BPA on rainbow trout metabolome at hatch and first feed. The results suggest that pathways involved in energy metabolism are targets for BPA impact and should be investigated as potential markers for BPA toxicity. Overall, BPA accumulation in oocytes induces long-term delays in growth and stress axis maturation in F1 generations fish, and these effects persist in the F2 generation. The developmental profiles of key genes of the somatotropic and HPI axes were altered by BPA, along with whole body composition, suggesting that BPA exposure leads to a metabolic disturbance in fish, resulting in reduced growth. Additionally, the altered plasma cortisol response to acute stress in F1 and F2 juveniles provides evidence for multigenerational effects of BPA on stress axis functioning. The current study proposes that BPA-induced epigenetic modifications during early development may be playing a key role in the generational effects on growth and stress axes disruption in trout. The finding that the growth and developmental changes to BPA exposure also corresponds with endocrine and metabolome changes in multiple generations in trout is novel, and underscores the necessity to develop new risk assessments tools for chemicals that are maternally transferred in fish.

Cell-cycle checkpoint proteins help maintain genomic integrity by sensing damaged DNA and initiating DNA repair or apoptosis. Checkpoint protein activation to cell-cycle damaging agents can involve post-translational modifications and these alterations provide a means to determine whether DNA in a cell is damaged or not. Steinmoeller et al. (2009) showed that checkpoint proteins are suitable biomarkers for detecting genotoxins in Oncorhynchus mykiss (rainbow trout). In this project, two evolutionarily conserved checkpoint proteins, Rad1 and Hus1, have been cloned from rainbow trout and antibodies against these proteins were developed. This is the first time that either Rad1 or Hus1 has been characterized in rainbow trout. For rtRad1, it was determined that the open-reading frame was 840bp, which encodes 279aa with a predicted protein size of 31kDa. The rtRad1 amino-acid sequence is highly conserved and contains conserved exonuclease and leucine zipper domains. RT-PCR was used to identify alternatively spliced variants of rtRad1 and it appears that these variants encode different sized Rad1 proteins that are tissue and cell-line specific. A Rad1 splice variant that encodes an 18kDa protein appears to be abundant only in heart tissue and in the RTgill-W1 and RTbrain-W1 cell-lines. A genotoxicity study was completed where RTgill-W1 and RTbrain-W1 cells were treated with bleomycin, which induces double-stranded DNA breaks. In RTgill-W1, levels of an 18kDa Rad1 protein increased in a dose-dependent manner while in RTbrain-W1 the Rad1 levels remained the same. It appears that this 18kDa Rad1 protein may be directly involved in maintaining genomic integrity and shows potential to be used as a genotoxicity biomarker. This is the first time that an isoform of Rad1 has shown to be modified in the presence of a damaging agent. Both Rad1 and Hus1 need to be further characterized to determine their usefulness as genotoxicity biomarkers.

Influence of triazine based pesticide (Sencor 70 WG - active substance metribuzine) was assessed via biochemical and hematological blood profile determination of experimental fish. As experimental fish we used common carp (Cyprinus carpio L.) and rainbow trout (Oncorhynchus mykiss ). Before rating the Sencor 70 WG pesticide influence on biochemical and hematological blood profile we accomplished a preliminary test to determine a concentration range and after that a basic acute toxicity test to determine 96hLC50 value. Both fish samples fingerlings were used for performing the tests. After 96hLC50 determination two groups of experimental fish (aged 1-2 years) were under this concentration and one control group without the substance. The test was processed according to the OECD methodology No. 203. Fish dissection was performed after the test. The increased amount of phlegm of water consistency on the body surface was found out. The fish were of dark colour in contrast with the control group. The ventricle was larger and containing transudate. An outstanding vascular profusion of internal organs in the ventricle was found out. Biochemical profile of the rainbow trout (Oncorhynchus mykiss ) experimental group under 96 hour acute operation of pesticide Sencor 70 WG (89,3mg.kg-1) proved significant lowering (p<0,01) of total proteins (TP), triglycerides (TRIG), aspartate aminotransferase (AST), amonnia (NH3), alcaline phosphatase (ALP) and Ca2+ in the blood plasma in contrast with the control group. Hematological profile of the same group proved significant lowering (p<0,05) of the number of erythrocytes (Er), haematocrit (PCV), and significant increase (p<0,05) of erythrocyte haemoglobin (MCH) value in contrast with the control group. Biochemical profile of the common carp (Cyprinus carpio L.) experimental group under 96 hour acute operation of pesticide Sencor 70 WG (250,2 mg.l-1) proved significant lowering (p<0,01) of total proteins (TP), triglycerides (TRIG), lactate dehydrogenase (LDH), Ca2+ and inorganic phosphate (PHOS) and significant increase (p<0,01) of glukose (GLU) and amonnia (NH3) concentration in the blood plasma in contrast with the control group. Hematological profile of the same group proved significant lowering (p<0,01) of the haematocrit (PCV), erytrocyte haemoglobin (MCH), mean erytrocyte volume (MCV) and number of leukocytes (Leuko) in contrast with the control group.

Parmi les œufs de poisson, qui sont une ressource aquatique nutritionnelle intéressante, ceux de la truite arc-en-ciel (Oncorhynchus mykiss) contiennent une quantité élevée de protéines et une huile riche en acides gras polyinsaturés (AGPI), avec une proportion très importante de phospholipides. Cependant, l’œuf de poisson présente une capacité élevée d’auto-protection contre les contraintes extérieures, qui limite la destructuration de son réseau protéique par attaque enzymatique. Ainsi, le degré d’hydrolyse des œufs de la truite l’Alcalase®, la Neutrase® et la Protamex® varie entre 3 et 7 %, ce qui est très faible (20 % dans la majorité des protéines animales). L’extraction des lipides après protéolyse partielle est incomplète, probablement en raison d’interactions fortes avec les protéines faiblement hydrolysées. Ils contiennent une teneur élevée en phospholipides (53 % des lipides totaux) et les acides gras polyinsaturés entrent pour 42 % des acides gras totaux. Les AGPI, notamment le DHA, sont situés préférentiellement en position sn-2 sur la molécule de glycérol ce qui est particulièrement intéressant du point de vue nutritionnel. La stabilité à l’oxydation de l’huile a été étudiée par diverses méthodes, dont la spectrométrie infrarouge à transformée de Fourier. Cette méthode s’est avérée extrêmement intéressante pour une analyse structurale de la dégradation de l’huile en cours d’oxydation. Il peut être conclu que les lipides tirés des œufs de la truite arc-en-ciel ou de poisson en général, ont un réel avenir en matière de complément alimentaire ou nutraceutique, à condition de lever l’obstacle de l’hydrolyse enzymatique des protéines du chorion et du vitellus / Fish eggs, especially those of the rainbow trout (Oncorhynchus mykiss) in the present study, are an interesting nutritional aquatic source. They contain proteins of high value, as well as an oil rich in polyunsaturated fatty acids (PUFA) with a large percentage of phospholipids. However, they exhibit a high auto-protection capacity against environmental constraints and thus, the degree of hydrolysis of rainbow trout eggs by Alcalase®, Neutrase® and Protamex® proteases varied solely within 3-7 %. This value was low compared with the 20 % obtained in most animal proteins. The phospholipid content was high (53 % of total lipids) and PUFA accounted for 42 % of total fatty acids. Among PUFA, DHA was found preferably at the sn-2 position of the glycerol backbone, which is of special interest about nutritional properties. The oil release by enzymatic hydrolysis was found limited compared with chemical methods, probably because of the strong interactions engaged with the incomplete destructured protein network. The oxidative stability of the oil was studied through several methods in which the infrared Fourier transform appeared as the best tool for structural analysis along the oxidation process. As a conclusion, lipids from fish eggs, especially from rainbow trout, could be a nutritional breakthrough, as far the enzymatic hydrolysis of the vitellus and of the chorion proteins is achieved

Approximately 24 alien fish species, equivalent to 9 percent of all South African freshwater fish species, were introduced and established into South African waters during the 19th and 20th Centuries (Skelton, 2001). Of the 24 species introduced, the Rainbow trout and the Brown trout have over time become South Africa's most widely spread and used freshwater fish species (Bainbridge, Alletson, Davies, Lax and Mills, 2005). The National Environmental Management: Biodiversity Act, no.10 of 2004 has, however, cast considerable doubt on the future of trout as a food source and a recreational fishing resource in South Africa. More specifically, Section 64 of the Act has the following aims: “(a) to prevent the unauthorized introduction and spread of alien species and invasive species to ecosystems and habitats where they do not naturally occur; (b) to manage and control alien species and invasive species to prevent or minimize harm to the environment and to biodiversity in particular; and (c) to eradicate alien species and invasive species from ecosystems and habitats where they may harm such ecosystems or habitats.” The uncertainty surrounding the future of trout in South Africa is mainly underpinned by aim (c) of Section 64 of the Act. Regarding the eradication of trout and in keeping with aim (c) of Section 64 of the Act, three remarks can be made. First, there exists a paucity of published studies which offer validated proof of the impacts which may be ascribed entirely to the introduction of alien trout in South Africa, since no pre-stocking assessments were conducted (Bainbridge et al., 2005). Second, the elimination of trout is feasible in a few limited closed ecosystems, such as small dams, but is highly impractical and untenable from an environmental and cost perspective where open and established river systems are concerned (Bainbridge et al., x 2005). More specifically, there are no efficient or adequate eradication measures which may be used in wide-ranging open ecosystems, which selectively target alien fish species. Moreover, most, if not all, measures have the potential to cause considerable adverse impacts on indigenous aquafaunal species. Finally, the elimination of trout could undermine the tourism appeal of many upper catchment areas in South Africa. The trout fishing industry is well established and is a source of local and foreign income, as well as a job creator in the South African economy (Bainbridge et al., 2005; Hlatswako, 2000; Rogerson, 2002). In particular, the industry provides a two-tier service: first, in food production at the subsistence as well as commercial levels, and second, as an angling resource. Recreational angling, including fly-fishing for trout, is one of the fastest growing tourism attractions in South Africa. Furthermore, the trout fishing industry is sustained and underpinned by a considerable infrastructure consisting of tackle manufacturers and retailers, tourist operators, professional guides, hotels, lodges and B&Bs. The economic case for the trout fishing industry in South Africa has, however, not been convincingly made. The economic benefit provided by trout and trout fly-fishing is priced directly in the market place by expenditures made by fly-fishers, and indirectly in property values, which provide access to fly-fishing opportunities. The benefit of trout and trout fly-fishing can also be valued through non-market valuation techniques. Non-market valuation is used to calculate values for items that are not traded in markets, such as environmental services. There are several non-market valuation methods available to the researcher, namely those based on revealed preference and those based on stated preference. The former includes the hedonic pricing method and the travel cost method, while the latter includes the contingent valuation method and the choice modelling method. Of the available non-market valuation techniques, the travel cost method is the most suitable method for determining the value of trout and the trout fishing industry because travel cost is often the main expenditure incurred. xi The aim of this study is threefold: first, to value the economic contribution of trout and trout fly-fishing to the Rhodes region, North Eastern Cape; second, to determine the willingness-to-pay for a project that entails the rehabilitation and maintenance of trout streams and rivers in and around Rhodes village so as to increase their trout carrying capacity by 10 percent; third, to determine the willingness-to-pay for a project aimed at eradicating trout from streams and rivers in and around Rhodes village so as to prevent trout from harming the indigenous yellowfish habitat. The first aim was achieved by applying the travel cost method, whereas the second and third aims were achieved by applying the contingent valuation method. The study aimed to provide policy makers with information regarding the value of trout fishing in the Rhodes region, so as to create an awareness of the economic trade-offs associated with alien fish eradication. Through the application of the travel cost method, the consumer surplus per trout fly-fishermen was estimated to be R19 677.69, while the total consumer surplus was estimated to be R13 774 384.40. The median willingness-to-pay for a project to rehabilitate trout habitat was estimated to be R248.95, while the total willingness-to-pay amounted to R199 462.20. The median willingness-to-pay for a project to eradicate alien trout from the Rhodes region rivers and streams was estimated to be R41.18, while the total willingness-to-pay amounted to R28 829.36. This study concludes that trout and trout fly-fishing make a valuable economic contribution to the Rhodes region. The extent of the economic benefit provided by trout and trout fly-fishing services in the Rhodes region should be carefully considered in any stream management project.

Recovery from exhaustive exercise in the white muscle of rainbow trout (Oncorhynchus mykiss) was used to examine the role of the adenylates in the control of energy metabolism and to assess the validity of equilibrium models of the behaviour of the high energy phosphates. The difficulty of obtaining muscle samples from fish makes detailed analysis of the behaviour of the labile high energy phosphates complex. The use of a new sampling procedure, the infusion of a lethal dose of anaesthetic via an indwelling cannula, minimized this problem. At exhaustion [ATP] and [PCr] were depressed by 75 and 80% respectively relative to the resting values. [ATP] depletion was mirrored by a stoichiometric increase in [IMP]. During recovery [PCr] returned to the resting level within 2 hours, but [ATP] recovery was slow and not complete until 24 hours post exercise. In contrast, energy charge and RATP(the proportion of the free adenylate pool phosphorylated to ATP) were, if anything, higher than the resting values by 2 hours post exercise. Therefore, [ATP] and energy status can be dissociated in tissues like fish white muscle because of the action of the purine nucleotide cycle. At 2 hours post exercise the calculated free ADP concentration dropped to less than one tenth the value at rest. As a result the [ATP] / [ADP] free ratio increased by nearly 6 fold. This condition may be required for glycogen resynthesis from lactate in muscle. Several similar equilibrium models of the behaviour of the adenylates and PCr were applied to the fish white muscle system. In general, the models well describe the relationship between the high energy phosphates. However, the definition of the high energy phosphate pool introduces some complications since this includes the total [ATP]. Because of the action of AMP deaminase the [ATP] concentration can change without measurable changes in the energy status, which is not considered in any of the models. As long as the extent of IMP formation is known the models can be applied, but since the formation of IMP may vary from fish to fish or with exercise regime the models lose much of their predictive power. / Science, Faculty of / Zoology, Department of / Graduate

The effect of transferring fish from water at pH 7.0 to either more acid or more alkaline conditions was to reduce the maximum critical velocity of the fish. In water of pH 4.0, 5.0, and 10.0, the maximum critical velocity was only 54.5%, 66.5%, and 61% respectively of that recorded for fish in the water of pH 7.0. Thus, both acid and alkaline conditions in the water reduce the aerobic swimming capacity of trout. Exposure to acid conditions increased mucus secretion and this was associated with an increase in coughing and breathing frequency in resting fish. Coughing rate increased from 41/hr to 592/hr; and respiration frequency increased from 81/min to 104/min when fish were transferred from water at pH 7.0 to water at pH 4.0. In comparing fish exposed to acid and alkaline waters, the results indicates that fish have a greater capacity to regulate blood pH in acid than in alkaline conditions. The gill potential was strongly dependent on water pH, being negative in neutral water, but positive in acid water and more negative in alkaline solution. Catecholamine levels increased significantly during acid exposure, but were not altered during alkaline exposure. The increasing catecholamine levels appeared at different time periods in different fish during acid exposure and seemed to be associated with the death of the fish. Na⁺ and C1⁻ ion concentrations in plasma decreased significantly after 24hrs of acid exposure, but did not change significantly in alkaline water. This may indicate that ionoregulatory disturbance in plasma is one of the reasons for the decrease in the maximum critical velocity in acid water, but not in alkaline water. / Science, Faculty of / Zoology, Department of / Graduate