Photoinduced toxicity of retene to Daphnia magna under enhanced UV-B radiation.

The effects of UV radiation on the acute toxicity of retene (7-isopropyl-1-methylphenanthrene) to Daphnia magna Straus were studied. Dehydroabietic acid (DHAA) from which retene is formed in the vicinity of pulp and paper industry was also studied. Pyrene, anthracene, and phenanthrene were used as model PAH compounds. The time taken for immobilization (ET50) was monitored under biologically effective UV-B dose rates of 240, 365, 565, and 650 mW m(-2) (UV-A and visible light also present). Median effective concentrations (EC50) were determined after a 15-min UV exposure (565 mW m(-2)) followed by 24 h in the dark. Retene (10-320 microg l(-1)) was not acutely toxic in the dark. The induction of phototoxicity was in agreement with the absorption properties of the compounds (absorption peak of retene at around 300 nm). Photoinduced toxicity followed an order pyrene > anthracene > retene. Phenanthrene and DHAA were not acutely phototoxic. Accumulation of the compound in Daphnia before UV exposure was essential. Some changes in the absorption spectra of the compounds were seen after a 5-h UV irradiation (565 mW m(-2)), but none of the irradiated compounds were acutely toxic without further UV exposure. Therefore, the enhanced acute toxicity was primarily due to internal photosensitization reactions rather than photomodification. The dissolved fraction of 25% pulp and paper mill effluent reduced phototoxicity by attenuating UV radiation. The phototoxicity of retene was a function of both the exposure concentration and the UV-B dose rate, but relatively high UV-B dose rates and concentrations were needed for the acute photoinduced toxicity.

Impact of UV radiation on the early development of the giant kelp (Macrocystis pyrifera) gametophytes.

The mechanisms and dose-response of UV action on the early development of Macrocystis pyrifera (L.) C. Agardh gametophytes were investigated. Post-release, zoospores undergo germination, germ tube elongation, DNA synthesis, nuclear division and translocation, which were followed for 41 h under laboratory conditions. The spores were exposed to UV radiation before germination (3 h post-release) or before nuclear division (20 h post-release). Biologically effective UV-B doses (BEDDNA300 nm) higher than those used in the experiments are needed for a 50% inhibition in germination (BED50 > 1600 J m-2). Nuclear division/translocation was more sensitive to UV radiation. When the spores were cultured in the dark, UV exposure at both 3 and 20 h post-release resulted in a dose-responsive inhibition of nuclear division/translocation (BED50 64 and 86 J m-2). Culturing in the light indicated recovery in the spores that were irradiated at 3 h post-release (BED50 356 J m-2), whereas no light-dependent recovery occurred within 41 h of culture when irradiated at 20 h post-release (BED50 80 J m-2). The results present a possible mechanism of UV inhibition in early life stages of the giant kelp, suggesting that environmentally relevant UV-B levels can perturb or delay the development and recruitment of the gametophytes by inhibiting nuclear events.

Biomarker responses in whitefish (Coregonus lavaretus L. s.l.) experimentally exposed in a large lake receiving effluents from pulp and paper industry.

Physiological and biochemical biomarker responses were studied in juvenile whitefish (Coregonus lavaretus L. s.l.) exposed experimentally to effluent from the forest industry. The large study area (609 km2), Southern Lake Saimaa, in Southeast Finland, receives 330,000 m3 d-1 of biologically and 55,000 m3 d-1 of chemically treated effluents, discharged from two integrated elementary chlorine free (ECF) bleached kraft pulp and paper mills, from one ECF pulp mill, and from one mill producing unbleached pulp and cardboard. The assessment of exposure to effluent discharged from the mills was based on lake water chlorophenolics (CPs) and resin acids (RAs) measured in samples collected from the 22 experimental sites along the area. Despite the low levels of effluent constituents in the lake, they were still accumulated in detectable levels in fish bile, indicating an exposure to the bioactive compounds of effluents. In comparison to the reference area, a two- to four-fold increase in ethoxyresorufin O-deethylase (EROD) activity was observed in whitefish exposed in the vicinity (1-6 km) of all the mills. However, cytochrome P450 1A1 (CYP1A1) gene expression was increased in only one of the receiving areas, indicating higher sensitivity of the EROD activity in the present study. There were no statistically significant correlations between EROD activity and the ambient water concentrations of the CPs, the RAs, or effluent dilution expressed by water sodium concentration. Neither bile chlorophenolics nor bile resin acids showed a significant correlation with EROD. No significant changes in circulating reproductive steroids, 17beta-estradiol and testosterone, in juvenile whitefish were observed. The vitellogenin gene was expressed in the vicinity of the pulp mill discharging the most wood-derived compounds, i.e. resin acids and wood-sterols, including beta-sitosterol. No differences were observed in plasma immunoglobulin M, glucose, or lactate concentrations between the effluent sources.

Pentachlorophenol accumulation in the freshwater mussels Anodonta anatina and Pseudanodonta complanata, and some physiological consequences of laboratory maintenance.

Freshwater mussels Anodanta anatina and Pseudanodonta complanata were exposed to (14C)-pentachlorophenol. The wet weight based bioconcentration factor (BCF = activity in animal per activity in water) at steady state varied from 80 to 120 for A. anatina and from 61 to 85 for P. complanata. The species did not differ significantly in their wet weight or lipid based BCFs but dry weight based values were significantly higher (40-50%) for A. anatina. The soft tissue dry weight and dry weight based condition index of A. anatina (Cl4 = soft tissue dry weight per shell length) differed significantly between natural mussel populations. In animals kept from 4 to 8 months in laboratory conditions, the soft tissue dry weight and glycogen content decreased more rapidly when mussels were maintained at 15 than at 5 degrees C. However, glycogen content in the digestive gland or adductor muscle did not differ in mussels maintained in the laboratory (5 degrees C) when compared to the natural population. The adductor muscle protein content differed between laboratory maintained animals and the natural population in Lake Höytiänen but there was no difference in the soft tissue lipid content. Trace metal concentrations and calcium in the soft tissue were in general higher in laboratory maintained mussels. In addition, laboratory maintenance affected the reproductive cycle of A. anatina.

Accumulation and depuration of chlorinated phenolics in the freshwater mussel (Anodonta anatina L.).

Uptake from ambient water and the depuration of five chlorinated phenolics, two chloroguaiacols (3,4,5-tri- and tetrachloroguaiacol), and three chlorophenols (2,4,6-tri-, 2,3,4,6-tetra-, and pentachlorophenol) were studied in the duck mussel (Anodonta anatina). Groups of animals were exposed at four acclimiation temperatures (3, 8, 13, 18 degrees C) to four chlorophenolic concentrations (total 6-56 micrograms/liter). The depuration was monitored for 72 hr. For the analysis of individual chlorophenolics by the GC/ECD technique, the soft tissue of mussels was homogenized, spiked with internal standard, acetylated, and extracted with n-hexane. The bioconcentration factors (BCF) (concn. in animal wet wt./concn. in water) were determined for mussel soft tissue. The highest BCF was found for pentachlorophenol (81-461) and the lowest for trichlorophenol (14-125). Neither water temperature nor exposure concentration affected the BCFs. The compounds studied were depurated rapidly and their depuration half-lives (T1/2) in soft tissue were generally less than 24 hr.

Uptake and body distribution of chlorinated phenolics in the freshwater mussel, Anodonta anatina L.

Freshwater mussels (Anodonta anatina L.) were exposed to [14C]pentachlorophenol (PCP) and [14C]3,4,5-trichloroguaiacol (CG-3) under laboratory conditions. Uptake and body distribution in mussels as well as total water-soluble metabolites of chlorophenolics in hemolymph and digestive gland were measured. The time course of chlorophenolic accumulation in the mussel soft tissue was followed by analyzing the decrease in the radioactivity in exposure water. The bioconcentration factors (BCFs, activity in animal per activity in water) were measured at steady state for the soft tissue homogenate and separate organs. Both chlorinated phenolics reached a steady-state concentration during the first 24 hr. BCFs in soft tissue ranged from 145 to 342 for PCP and 34 to 125 for CG-3. Accumulations by the digestive gland (hepatopancreas) and kidneys were 2 and 1.3 times greater, respectively, than the average accumulation by the whole soft tissue. The water-soluble fraction of PCP (1-8%) and CG-3 (0.4-2.9%) in separate organs implied only a minor metabolism of chlorophenolics in this animal.

Determination and characterization of chloroguaiacol conjugates in fish bile by HPLC.

In this study a small-scale technique for direct analysis of metabolic conjugates of 4,5,6-trichloro- (CG-3) and tetrachloroguaiacols (CG-4) in fish bile by RP-HPLC is presented. Only one metabolite, glucuronic acid conjugate, was demonstrated in two Lake Baikal fishes (Leuciscus leuciscus baikalensis and Cottus kessleri) exposed to CG-3 or CG-4 at 6 degrees C for 1-2 days. In Leuciscus the ratio between free CG-4 in the ambient water and conjugated CG-4 in the bile averaged 264,000. Intraperitoneal injections of tetrachloroveratrol (CV-4) into Thymallus arcticus baikalensis did not reveal any traces of free CV-4 or CG-4 glucuronide in the bile in 2 days at 5 degrees C. We therefore suggest that CV-4 was not demethylated and subsequently conjugated with glucuronic acid in the liver of this fish species.

Subacute physiological effects of bleached kraft mill effluent (BKME) on the liver of trout, Salmo gairdneri.

Rainbow trout (Salmo gairdneri) were exposed for 10 and 30 days to microbiologically treated effluent of a bleached kraft pulp and paper mill (BKME). Throughout the experiments, the quality of dilution water, taken from an upstream location close to the mill, was allowed to vary both diurnally and seasonally (September-October) in a natural manner. The test concentrations averaged 0 (control), 0.6, 1.2, 2.0, and 5.1% (v/v) of BKME. Conjugates of all major resin acids and chlorinated phenolics of BKME, except chlorocatechols, were detected in trout bile. They comprised 93.1-99.9% of the total amounts in the bile. The level of conjugated resin acids increased linearly with the content of BKME in test water. On the other hand, no increase in concentration of conjugated phenolics was seen above 2.0% BKME. In the blood plasma no conjugates were analyzable. Concentrations of free resin acids in the blood plasma, but not in the bile, significantly increased at high test concentrations of BKME. No active excretion of free resin acids from plasma to bile can be inferred, but some of the phenolics--particularly 3,4,5,6-tetrachloroguaiacol--seem to be concentrated in the bile as a free compound. Changes in several biochemical parameters did not display any simple relationship with the external concentrations of BKME. In intermediate exposure concentrations, however, liver RNA and protein concentrations were decreased after 10 days but increased after 30 days. Condition of fish, relative size of the liver, and concentrations of liver glycogen and water were unresponsive to BKME at the dilutions investigated.

Renal excretion of magnesium in a freshwater teleost, Salmo gairdneri.

Infusion of magnesium salts into the body cavity of freshwater-adapted rainbow trout led to elevated plasma magnesium concentrations and to stimulation of renal tubular secretion of magnesium. The majority of the infused load was excreted renally, no net branchial excretion being detected. Magnesium sulphate infusion led to increased tubular secretion of sulphate. Magnesium chloride infusion led to reduced tubular reabsorption of chloride. Magnesium could either be reabsorbed or secreted in control freshwater-adapted trout, apparently as a function of nutritional status. Fish could switch from reabsorption to secretion in response to magnesium loading. It is suggested that freshwater fish eliminate excess dietary magnesium renally.

Physiological changes in trout (Salmo gairdneri) during a short-term exposure to resin acids and during recovery.

Six rainbow trouts were exposed to a 2 mg/l concentration of resin acids for 24 h. The toxicants influenced respiration by causing a decrease in arterial P02, red cell volume and pH, and an increase in ATP/Hb ratio. These responses were reversible on recovery. A disturbance in hydromineral balance was shown by a decrease in plasma chloride concentration, which was reversible in all but one fish. This fish had additional metabolic difficulties as shown by increases in plasma lactate concentration and enzyme activity. An indication of liver dysfunction was the increase in plasma bilirubin concentration, continuing throughout recovery.