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One-year-old whitefish, Coregonus lavaretus, were exposed to three types of iron-rich water, two dilutions for each, in a subchronic (30-day) experiment. In natural iron-rich humic water, both the bioaccumulation and physiological effects of iron exposure were negligible. Inhumic-free water with high amount of additional inorganic iron (nominally 8 mg Fe/L), Fe accumulated in gills, liver, and gut. This accumulation was accompanied by decreased glycogen phosphorylase activities and microsomal EROD activity in the liver as well as decreased plasma sodium and potassium concentrations. The third group of whitefish were exposed by adding inorganic iron (nominally 2 and 8 mg Fe/L) to natural iron-rich humic water. Fish exposed to the higher concentration of waterborne iron exhibited a physiological stress response as indicated by increased blood lactate and plasma cortisol concentrations. Additionally, plasma 17beta-estradiol concentration was increased in fish kept in both water conditions with high amounts of additional iron. The observed dissimilarities in bioaccumulation and in physiological responses were not connected with the measured amounts of totalor disolved iron in water, but to the amount of additional iron in tanks and to the different water conditions with or without organic matter. The dissimilarity of physiological responses, which was also shown by statistical classification through multivariate discriminant analysis, points to the necessity of variable and complementary physiological endpoints in describing the effects of similar kind of exposures. [ABSTRACT FROM AUTHOR]

To corroborate the responses in whitefish (Coregonus lavaretus L.) exposed to elemental chlorine free (ECF) bleached-kraft pulp mill effluent (BKME) in situ. a 30-d laboratory exposure was carried out at concentrations simulating the field conditions. The flow-through exposures were conducted at four secondary (activated sludge) treated effluent (STE) concentrations: 1.3, 2.3, 3.5, and 7%. To evaluate the roleof the secondary treatment, fish were also exposed to one concentration (3.5%) of pretreated effluent (PTE) from the mill. Compared to the control, whitefish liver 7 -ethoxyresorufin-O-deethylase (EROD) activity was twofold in fish exposed to 3.5% STE, which was similar to monooxygenase induction in the field at the same effluent dilution. The exposure to 3.5% PTE caused a 12-fold relative induction in whitefish. The activity of pentoxyresorufin dealkylase showed a high correlation with EROD activity (r2 = 0.85, p < 0.01). The plasma concentration of 17Beta--estradiol was reduced by 37% (p < 0.05) in fish exposed to 3.5% STE, whereas testosterone was reduced by about 40% (p < 0.05) in fish in both 3.5% STE and PTE groups. The accumulation of chlorophenolics (CPs) and resin acids (RAs) in the bile of the fish was negligible at the three lowest STE concentrations, reflectingthe nearly nondetectable levels of CPs and RAs in secondary treated whole effluent. The measured blood parameters plasma immunoglobulin M, glucose, hemoglobin, and hernatocrit were not affected by effluent exposure. The responses obtained from the laboratory simulation well accorded with the exposures in the field, although signs of reproductive impairment could be detected in the laboratory. Overall, however,it is evident that the improvements to mill processes and wastewatertreatment have substantially reduced the load of harmful constituents in bleached-kraft mill effluent and biological impacts in the receiving environment. [ABSTRACT FROM AUTHOR]

Two-year-old whitefish (Coregonus lavaretus) were exposed for 30 days to episodic iron overload in iron-rich humic water (5%) supplemented with inorganic iron (5 mg FeL(-1)). Two parallel laboratory exposures were performed, one under conditions simulating winter and the other under conditions simulating spring. After exposure, some of the fish were subjected to acute handling stress in the form of a short air challenge to reveal possible modification of the primary and secondary stress responses. In whitefish sampled without additional handling, iron accumulated in the liver (under spring conditions) and gills (under winter and spring conditions); plasma catecholamine and beta-estradiol (both winter and spring groups) as well as blood hematocrit (winter group only) levels were depressed; blood glucose (winter group only) and red blood cell (RBC) Na+ levels (spring group only) were increased. In handled whitefish, liver glycogen phosphorylase (GPase), RBC, and blood glucose stress responses were impaired by the applied exposure conditions, which reflected natural iron-rich humic water. Exposure also removed some physiological effects of the applied ambient conditions: plasma catecholamines and beta-estradiol, gill Na+/K+ -ATPase, and RBC K+ concentration were not different in two iron-exposed fish groups, whereas there was a difference in reference fish. Thus, the physiological effects of this type of subchronic exposure, together with alterations in the acute stress response, can lead to incorrect conclusions being drawn from the results, if the effects of time-dependent stress response are ignored. In conclusion, waterborne iron overload may impair the optimal capacity of whitefish to carry out their normal physiological functions such as responding to external threats.

Exposure to biologically treated bleached kraft mill effluent (BKME) is demonstrated to greatly modify the acute physiological stress response in fish and, accordingly, to lead to inconsistencies in data interpretation due to dissimilar effects of handling procedures on reference and exposed fish. To consider this phenomenon, juvenile whitefish (Coregonus lavaretus) were caged for 30 days in four reference sites and in three areas influenced by different BKME discharges. After exposure, fish were subjected to the impacts of low-level handling by raising the cages to the water surface, serially handnetting the fish, and transferring ( approximately 10 min) the submerged cages to the research vessel. The data on physiological variables were pooled within each area to three groups according to the periods (<4 min, 10-20 min, 21-40 min) from the onset of handling to the sampling of individual fish. BKME-exposed whitefish sampled during the first period exhibited lower plasma cortisol and blood lactate levels and higher red blood cell Na+ concentrations than reference fish sampled during the same period. In reference whitefish, along with increased plasma cortisol and blood lactate levels, gill ATPase activity as well as liver glycogen and blood glucose levels were markedly affected by the handling procedure, while the latter three responses were strongly attenuated in exposed whitefish. Red blood cell Na+ and K+ and blood hemoglobin responses vanished in only one mill area. These findings, in accordance with similar results of earlier studies dealing with the same species, point to the need for this kind of time-dependent approach to achieve reliable and comparable outcomes in field experiments and encourage work on determining the importance of functional deviations noted in fish exposed to anthropogenically modified water qualities.

Exposure to impaired water quality, as in bleached kraft mill effluents (BKMEs), has recently been demonstrated to impair the ability of fish to elicit an acute stress response. Acute stress caused by catching is, in most field studies, an unavoidable incident that may markedly affect physiological functions. Consistently, dissimilar stress responses to catching procedures in exposed and reference animals may lead to altered results. In this study, juvenile whitefish (Coregonus levaretus) were caged for 30 days in two reference areas and three areas affected by different BKMEs, and the immediate effects of low-level handling on physiological functions in four periods within an hour of the start of the disturbance were clarified. Both primary and secondary stress responses were evident and consistent in fish caged in the two reference areas. Instead, despite the strong cortisol response in fish caged in polluted areas, the secondary stress response was weak or altered with respect to all other measured parameters excluding blood glucose in two of the three polluted areas. Thus, exposed fish may, when compared with reference fish, give different results depending on the exact period from the onset of the catching disturbance to sampling, and therefore, the results may be masked or totally inverted. Because the impacts of acute stress on physiological parameters are immediate and, in exposed areas after low-level handling, dissimilar in nature, this study points to the necessity for time-dependent standardization in field studies whenever sampling is delayed., (Copyright 1999 Academic Press.)

The characteristics of the uptake of 3-O-methyl-d-glucose (3-OMG) by carp (Cyprinus carpio) erythrocytes were studied in vitro with tracer methods. There is large individual variation in the permeability of the carp erythrocyte membrane to 3-OMG. Although transport is inhibited by cytochalasin B and phloretin, the lack of saturation kinetics for transport in a physiologically relevant concentration range suggests either that a glucose transporter does not exist or that its affinity for glucose is extremely low. The marked increase in transport after osmotic swelling and the inhibition of swelling-induced glucose transport by cytochalasin B suggest that the glucose transport pathway in carp erythrocytes (both in isotonic and hypotonic conditions) may be similar to the volume-activated channel described for flounder erythrocytes. 3-OMG transport across the carp erythrocyte membrane is increased by catecholamines by a mechanism independent of the catecholamine-induced cell swelling.