Significance of concentrations of lead,cadmium, and iron in the plumage of the feral pigeon

Lead, cadmium, and iron contamination was examined in the plumage of feral pigeons. Metal contamination in pigeons from different regions in Bratislava or in different seasons did not differ significantly; seasonal type of food did not significantly influence the concentrations. The blood of birds was examined for the presence of complement fixing antibodies toChlamydia psittaci. Birds with antibodies did not contain significantly higher metal concentrations in the plumage than birds without antibodies. Juveniles contained significantly lower lead burdens than adults. Plumage lead concentrations increased with age of nestlings. Females and males did not differ significantly. Melanic juveniles possessed significantly lower levels of cadmium than wild types. Adults with body weight, head length or wing length above the average exhibited higher plumage cadmium concentrations than the birds with undersized body weight, head length or wing length.     

Cadmium accumulation and metallothionein-like proteins in the sea starAsterias rubens

Sea stars were exposed for four months to cadmium at 50 g Cd/L. The cadmium content of stomachs, pyloric caeca, gonads and body wall was determined after 2, 4, 6, 8, and 16 weeks of exposure. The highest accumulation rates were found for body wall and pyloric caeca. The lowest accumulation rate was found for the gonads. In all tissues cadmium accumulation showed saturation kinetics. The body wall contained the largest part of the accumulated cadmium.Sephadex G-75 gel filtration experiments demonstrated the presence of metal-binding, metallothionein (MT)-like proteins with a molecular weight of 10.8 kD in cytosolic fractions of pyloric caeca from unexposed sea stars. The MT-like proteins contained mainly zinc and a small amount of copper. During exposure, the MT-like proteins accumulated cadmium at a relatively high rate, but a steady state was reached after 8 weeks, indicating thatin vivo, the Cd-binding capacity of these proteins was limited. When pyloric caeca cytosol from unexposed sea stars was incubated with cadmiumin vitro, the MT-like proteins could bind larger amounts of cadmium thanin vivo during the Cd exposure. After 16 weeks of Cd exposure, thein vitro Cd-binding capacity had hardly increased.Low-molecular-weight metal-binding proteins were absent in cytosolic fractions of the testes, ovaries and oocytes from Cd-exposed sea stars, even after four months of exposure. The cadmium accumulated in the gonads was bound exclusively to high-molecular-weight proteins, which accumulated cadmium at a relatively low rate, compared to the MT-like proteins in the pyloric caeca. The absence of MT-like proteins in the gonads may explain the low cadmium accumulation rates found for these organs, but as a consequence, the accumulated cadmium is not detoxified.     

Effects of cadmium on metal composition and adenylate energy charge in the sea starAsterias rubens L

Sea stars,Asterias rubens, were exposed to 200 g Cd/L or fed with mussels which contained about 70 g Cd/g dry wt. After 5 weeks, cadmium in the pyloric caeca of directly and indirectly exposed sea stars had reached levels of 12 and 9 g Cd/g dry wt, respectively. For both types of exposure, a reduction of 30% of the zinc levels in the pyloric caeca was found, which was correlated with a comparable displacement of zinc from the metallothionein-like proteins. Copper levels were increased in the pyloric caeca of directly exposed sea stars.In gonads, stomachs, and body wall of directly exposed sea stars, cadmium concentrations were 4 to 9 times higher than those in animals fed with Cd-contaminated mussels. Cadmium exposure also affected metal composition in these tissues. The ovaries contained relatively large amounts of zinc. Gel filtration chromatography revealed that this zinc and the accumulated cadmium were distributed over a large range of high-molecular-weight proteins.Both direct and indirect cadmium exposure resulted in a small, but significant decrease of the adenylate energy charge (AEC) in the pyloric caeca. In the gonads, no effect of the cadmium exposure could be demonstrated on the AEC, but in the ovaries a reduction of the adenylate pool was found.In semi-field experiments, stars were exposed to 25 g Cd/L or fed with mussels collected from the heavily polluted Dutch Western Scheldt. After 6 months of direct or indirect exposure, cadmium in the pyloric caeca had reached comparable levels of 8 and 7 g/g dry wt, respectively. In the gonads of sea stars that had been fed with Western Scheldt mussels, cadmium levels were lower than those in directly exposed sea stars, but still about a factor 10 higher than those in unexposed animals. Exposure of sea stars to 25 g Cd/L for three months, had no effects on the levels of zinc, copper and magnesium or on the AEC in the pyloric caeca.     

Bioaccumulation of cadmium,lead, copper,and zinc in successive developmental stages of Lymantria dispar L. (Lymantriidae,Lepid)—a life cycle study

The forest pest insect Lymantria dispar L. (gypsy moth) was reared on an artificial diet contaminated independently with four metals at two different concentrations (2 and 10 g/g Cd, 4 and 20 g/g Pb, 10 and 50 g/g Cu, 100 and 500 gg Zn). Whole body metal concentrations were determined in each larval stage, pupae, imagoes, and F1 generation first instars and also of the corresponding exuviae, headcapsules, and faeces. The pattern of metal accumulation in successive developmental stages was metal and concentration (Cu, Zn) specific. Pb was barely assimilated by the larvae (concentration factor <0.4), whereas the concentration factors for the other metals were generally above 1 (the highest concentration factors determined for instars were: 3.5 (Zn), 4 (Cd), 5 (Cu)). All metals were eliminated via the meconium to a certain extent. In all groups, metal content was positively correlated with L. dispar larval weight. These relationships were also concentration dependent. F1-generation first instar larvae showed significantly higher metal contamination than controls, reflecting the metal burdens of the parental generation.     

The effects of In Vivo exposure to cadmium, copper and zinc on the activities of gill ATPases in the Norway lobster, Nephrops norvegicus

Norway lobsters, Nephrops norvegicus were exposed for 18 days to combinations of cadmium, copper and zinc at three sublethal concentrations (1, 5, 25 g/L for Cd and Cu, and 8, 40 and 200 g/L for Zn). Male animals were exposed to all three concentrations, while female animals were studied only in one (highest) concentration of the metals. Activities of Na,K-ATPase and both oligomycin-sensitive and insensitive Mg-ATPase were investigated in relation to metal exposure. A group of male Nephrops of different size groups from a single location in the Clyde Sea was also sampled to investigate the relationship between size and ATPase activity.Cadmium concentrations increased significantly with increases in exposure concentrations in both male and female animals, whereas copper and zinc increased significantly only in the highest treatment in males. There was no significant difference in concentrations of the metals in control male and female animals, whereas males accumulated significantly higher levels of copper and zinc in the highest concentrations of the metals. Control males showed higher activity of Na,K-ATPase than control females. Na,K-ATPase activity was significantly inhibited in male animals exposed to metals whereas in female animals there was only a significant inhibition in total Mg-ATPase activity. Na,K-ATPase activity had a negative relationship with copper in males, while in treated females this ATPase had positive relationship with zinc and copper. There were negative relationships between the activities of Na,K-ATPase and oligomycin sensitive Mg-ATPase with carapace length of the animals.     

The effects of host metal stress on a parasitoid in an insect/insect relationship (Lymantria dispar L., Lymantriidae lepid.—Glyptapanteles liparidis Bouchè, Braconidae hym.)

A host-endoparasitoid relationship was investigated under metal stress.Lymantria dispar (gypsy moth) larvae were reared on artificial diets contaminated with two concentrations of cadmium (2 and 10 g/g), lead (4 and 20 g/g), copper (10 and 50 g/g) and zinc (100 and 500 g/g), all based on dry weight. Following parasitization in the first premoulting period byGlyptapanteles liparidis, the eclosal success ofG. liparidis and the developmental rates of both species were investigated and compared with controls. Additionally, metal concentrations were monitored in host individuals and parasitoids by flame and flameless AAS. The developmental rate of the endoparasitoid positively correlated with that of the host. A negative relationship was found between the number of closedG. liparidis and the developmental rate of the host. No correlation was found between the extent of metal contamination and parasitization success.Correlation of results led to the conclusion that the elevated metal concentrations did not affectG. liparidis directly, but that parasitoid development is more likely to be influenced by alterations in the trophic situation within the host larvae due to metal stress.     

The toxicity of copper to the adult and early life stages of the freshwater clam,Corbicula manilensis

The copper sensitivity of adult and larval stages of the freshwater clamCorbicula manilensis was evaluated. In addition, copper concentrations were determined in adult clams exposed for 4 to 10 weeks to copper in a high-volume, flow-through bioassay. All bioassay systems utilized water that was low in total hardness and alkalinity.The response of the clams to copper depended on life stage. Copper sensitivity of larvae decreased markedly in successive developmental stages. LC50₂₄'s of veliger and juvenile larvae were 28 and 600 g Cu/L, respectively. The mortality of trochophore larvae exposed to 10 g Cu/L for one hr was 91.5%. The sensitivity to copper decreased with increased amounts of larval shell deposition.Adult clams were resistant to copper; the LC50₉₆ was greater than 2,600 g Cu/L. By comparison, the incipient lethal concentration (ILC, was lowless than 10 g Cu/L. Adult clams accumulated more copper as concentrations in the water increased. Evidence was obtained for copper loss near or at death.Labile and total copper, as well as the coppercomplexing capacity, in the bioassay water were determined; the majority of copper was present as labile species. Toxicity was related to the quantities of labile copper in the water.This work was supported by the U.S. Nuclear Regulatory Commission (Memorandum of Understanding with the U.S. Department of Energy) and by the U.S. Department of Energy (contract number W-7405-ENG-48).     

Accumulation and Elimination of Trace Metals in a Transplantation Experiment with Crassostrea rhizophorae

Oysters, Crassostrea rhizophorae, were reciprocally transplanted to two different sites: a contaminated site in the Cotegipe Channel at Aratu Bay and an uncontaminated site at Cacha-Prego, inside and outside of Todos os Santos Bay (Brazil), respectively. Trace metal accumulation was measured after 0, 15, 30, and 60 days of exposure at the contaminated site. Oysters transplanted for 60 days from the clean to the contaminated site had accumulated cadmium and lead to similar concentrations as found in the native oysters. They had also accumulated copper and zinc, but to lower levels compared to native specimens. Elimination experiments were carried out by transplanting oysters in the reverse direction. After 30 days, concentrations of cadmium and lead had decreased to levels comparable to those in the native specimen, whereas concentrations of copper and zinc did not diminish. A second elimination experiment, bringing back to Cacha-Prego oysters that had been exposed 60 days at Cotegipe Channel, indicated stronger decreases of copper and lead, but no clear changes of cadmium and zinc concentrations. The accumulation experiment with C. rhizophorae is useful to estimate trace metal bioavailability and changes in concentrations as a function of time at the contaminated site. The different results of elimination experiments in the uncontaminated site suggest different degrees of trace metal fixation after long-term and short-term accumulation periods. Received: 1 July 1998/Accepted: 12 May 1999     

An Assessment of Five Australian Polychaetes and Bivalves for Use in Whole-Sediment Toxicity Tests: Toxicity and Accumulation of Copper and Zinc from Water and Sediment

The suitability of two polychaete worms, Australonereis ehlersi and Nephtys australiensis, and three bivalves, Mysella anomala, Tellina deltoidalis, and Soletellina alba, were assessed for their potential use in whole-sediment toxicity tests. All species except A. ehlersi, which could not be tested because of poor survival in water-only tests, survived in salinities ranging from 18 to 34 during the 96-hour exposure period. No mortality was observed in any of the species exposed to sediment compositions ranging from 100% silt to 100% sand for 10 days, thus demonstrating the high tolerance of the five species to a wide range of sediment types. All species showed decreased survival after exposure to highly sulfidic sediments in 10-day whole-sediment tests. In 96-hour water-only tests, survival decreased, and copper accumulation in body tissues increased with exposure to increasing copper concentration for all species except A. ehlersi, which again could not be tested because of its poor survival in the absence of sediment. S. alba and T. deltoidalis were the most sensitive species to aqueous copper (LC50s of 120 and 150 g Cu/L, respectively). All species tested were relatively insensitive to dissolved zinc up to concentrations of approximately 1,000 g/L. In addition and with the exception of N. australiensis, all species accumulated significant levels of zinc in their body tissues. Whole-sediment tests were conducted over a 10-day period with copper-spiked (1,300 g/g) and zinc-spiked (4,000 g/g) sediments equilibrated for sufficient time to ensure that pore water metal concentrations were well below concentrations shown to have any effect on organisms in water-only tests. Survival was decreased in the bivalves T. deltoidalis and S. alba after exposure to copper-spiked sediments, and all species—except T. deltoidalis, in which 100% mortality was observed—accumulated copper in their tissues. Exposure to zinc-spiked sediments significantly decreased the survival of only one species, T. deltoidalis. Both polychaetes appeared to regulate concentrations of zinc in their body tissues with no significant uptake of zinc occurring from the sediment phase. Of the five species assessed in this study, T. deltoidalis was found to be the most sensitive to copper- and zinc-contaminated sediments, and based on commonly used selection criteria (ASTM 2002a, ASTM 2002b, ASTM 2002c) is recommended for development as test species in whole-sediment toxicity tests.     

Concentrations of lead,cadmium, mercury,and copper in the crayfish (Pacifasticus leniusculus) obtained from a lake receiving urban runoff

Commercially caught crayfish (Pacifasticus leniusculus) were placed in a municipal lake below a combined sewer overflow outfall and a storm drain outfall associated with elevated sediment metal concentrations. Abdominal muscle, viscera, and exoskeleton from each crayfish were analyzed for mercury, cadmium, lead, and copper. Crayfish metal concentrations for each sampling site were evaluated relative to unexposed samples from the commercial catch and samples held in the laboratory. Results indicated that 1) mercury accumulated in muscle tissue, highest cadmium concentrations were in the viscera, and highest lead concentrations were in the exoskeleton, 2) uptake of copper is well-regulated by the organism at non-toxic water concentrations, and 3) viscera concentrations of cadmium, lead, and copper tended to be higher and more variable than in muscle tissue. A significant correlation was found between body weight and muscle mercury concentration. Relative to allowable limits for metals in foods, there was not sufficient accumulation of any metal to indicate that a significant health hazard would result from consumption of these organisms. These data indicate that analysis of trace metals in various body parts ofP. leniusculus may be a useful biological indicator of trace metal pollution of freshwater lakes and streams.     

Investigation of Zinc,Copper, Lead and Cadmium Accumulation in the Tissues of <Emphasis Type="Italic">Sander lucioperca</Emphasis> (L., 1758) Living in Hirfanlı Dam Lake,Turkey

This study, some metals (zinc, copper, lead and cadmium) were analyzed in liver, muscle and gills of Sander lucioperca (Linnaeus, 1758) caught from the Hirfanlı Dam Lake in December 2007. The highest concentrations were found in liver (zinc:32.5 μg/g, lead:10.73 μg/g, copper:5.85 μg/g, cadmium:0.76 μg/g) of Sander lucioperca. It was seen that the accumulation of zinc, lead and cadmium primarily took place in liver followed by muscles and gills. It was observed that copper is mainly accumulated in liver followed by gill and mucsles.     

Heavy Metal Distribution in Chicks of Two Heron Species from Korea

This study presents concentrations of iron, manganese, zinc, copper, lead, and cadmium in tissues of black-crowned night heron (Nycticorax nycticorax) (n = 8) and grey heron (Ardea cinerea) (n = 9) chicks from Pyeongtaek heronry, Gyeonggi-do, Korea, 2001. Iron (respectively, 45.8 ± 24.0 μg/wet g, 155 ± 123 μg/wet g), zinc (38.3 ± 5.34 μg/wet g, 50.9 ± 14.0 μg/wet g), and copper (9.93 ± 2.26 μg/wet g, 30.2 ± 12.9 μg/wet g) concentrations in feathers, manganese concentrations in livers (3.26 ± 0.68 μg/ wet g, 1.50 ± 0.58 μg/wet g), kidneys (1.43 ± 0.27 μg/wet g, 0.84 ± 0.34 μg/wet g), and bones (1.34 ± 0.50 μg/wet g, 3.17 ± 1.31 μg/wet g) were different between black-crowned night heron and grey heron chicks. Lead concentrations in bones (0.11 ± 0.04 μg/wet g, 0.61 ± 0.42 μg/wet g) and cadmium concentrations in liver (13.5 ± 2.30 μg/wet kg, 10.3 ± 1.59 μg/wet kg), kidney (6.61 ± 2.54 μg/wet kg, 2.31 ± 1.29 μg/wet kg), and muscle (5.25 ± 5.91 μg/wet kg, 1.37 ± 0.90 μg/wet kg) differed between chicks of the two heron species. The differences of heavy metal concentrations in tissues in herons and egrets were reported to other similar studies. Heavy metal concentrations for both heron species were at background levels. In both species, lead concentrations were higher in livers than in bones and cadmium concentrations were higher in livers than in kidneys. We suggest that it is not chronic exposure but acute exposure to lead and cadmium contamination around breeding site that leads to these observations. Therefore, lead and cadmium concentrations in tissues can be used as a bioindicator of acute local contamination.     

Cadmium kinetics in freshwater clams. V. Cadmium-copper interaction in metal accumulation byAnodonta cygnea and characterization of the metal-binding protein

Freshwater clams were exposed for 61/2 weeks to cadmium chloride, at 48 ppb¹ Cd, or to copper chloride, at 47 ppb Cu, or to a mixture of the salts, at 122 ppb Cd+139 ppb Cu. The Cd-accumulation factor (AF) for whole animal was reduced by 90% in the presence of Cu. Cu-AF was reduced by 50% in the presence of Cd. Copper did not influence thein vitro uptake of Cd by the excised gill but increased the elimination of previously accumulated Cd. However, decrease of the ventilation rate probably accounts for the greater part of the Cu effect on Cd accumulation. In the cytosol, the two metals were partitioned between two protein fractions in gel permeation. Except for hepatopancreas, Cu was for the greater part bound to the high-molecular-weight fraction. Cadmium was mainly bound to a specific metal-binding, carbohydrate-containing protein fraction of M_r11,000. Co-exposure to copper increased the portion of Cd bound to this fraction.     

Copper/Metal Ratios in the Gills of Rainbow Trout (Oncorhynchus mykiss) Provide Evidence of Copper Exposure Under Conditions of Mixed-Metal Exposure

Previous work has suggested that the ratio of copper residues to zinc in the gills of rainbow trout may indicate short-term exposure to increased levels of waterborne copper. However, the effect of exposure to a combination of increased copper and zinc concentrates in the water column was unknown. We exposed rainbow trout to 8 ± 2 g L^–1, 40 ± 2 g L^–1 and 90 ± 9 g L^–1 of waterborne copper and 21 ± 3 g L^–1, 129 ± 40 g L^–1, and 202 ± 40 g L^–1 of waterborne zinc in a 2-factor experiments and gill copper and zinc residues were examined. Other gill parameters analyzed included the concentrations of calcium, magnesium, sodium, and potassium, liver copper and zinc concentrations and plasma copper, calcium, sodium, and potassium are also reported here. Copper residues in the gill filaments were significantly higher in the highest level of copper exposure (high Cu, 4.06 g g^–1; low Cu 2.41 g g^–1; 0 Cu 2.01 g g^–1; P = 0.001), whereas no differences were seen in zinc concentrations at any treatment level. Gill sodium and plasma calcium concentrations were also decreased at the highest waterborne copper concentrations. Although copper–zinc ratios in the gills were significantly different between the highest and lowest copper treatments (P = 0.002, F = 6.59), copper–sodium and copper–magnesium ratios were more sensitive to waterborne copper exposure (P = 0.001, F = 17.91 and P = 0.002, F = 15.45, respectively). These copper–metal ratios may be better indicators of copper loading in the water column.     

Cadmium in kidneys in Swedes measured in vivo using X-ray fluorescence analysis

An X-ray fluorescence (XRF) technique using plane polarized X-rays for excitation was used for in vivo measurements of cadmium in the kidney cortex among non-occupationally exposed members of the general population in southern Sweden. The measured concentrations of cadmium in the kidney cortex of smokers (median 28 g/g, n = 10) were significantly higher (P = 0.0036) as compared to those in non-smokers (median 8 g/g, n = 10), and so were the cadmium concentrations in blood and urine. The results show that smoking considerably increases the cadmium concentration in the kidney cortex and that smoking is a major source of cadmium exposure in the general population of Sweden. Except in the presence of very deeply situated kidneys, where the minimum detectable concentration is high, non-invasive in vivo XRF analysis of kidney cadmium should be a useful tool for evaluating the effects of long-term low-level exposure to cadmium and the risk of kidney damage.     

Selenium, Cadmium, Copper, and Zinc Concentrations in Sediments and Mullet (Mugil cephalus) from the Southern Basin of Lake Macquarie, NSW, Australia

Selenium, cadmium, copper, and zinc concentrations were measured in sediments and the tissues of mullet (Mugil cephalus) collected from the southern basin of Lake Macquarie, NSW, Australia. Trace metals in surficial sediments are enriched in trace metals relative to background concentrations (selenium, 3–19; cadmium, 14–42; copper, 1.5–3.6; zinc, 0.77–2.2 times background). Selenium, cadmium, and copper in Lake Macquarie mullet tissues are elevated compared to those in mullet collected from the Clyde River estuary, a relatively pristine location. Selenium and copper concentrations are also elevated compared to those reported in mullet tissues from other nonpolluted coastal environments. Zinc concentrations in Lake Macquarie mullet muscle tissues are significantly higher than those in muscle tissues of mullet from the Clyde River estuary, but mullet from both locations have similar zinc concentrations in other tissues. These results show that contamination of sediment with trace metals has resulted in elevated trace metals in the benthic feeding fish M. cephalus. Little of the variation of trace metal concentrations between fish was explained by variation in mass. Selenium concentrations in mullet are of concern in muscle tissues as they are above recommended acceptable limits for safe human consumption, while concentrations in tissues are at levels that may effect fish growth, reproduction, and survival. Copper concentrations in mullet tissues are also at levels that may reduce fish growth. Received: 11 September 1999/Accepted: 9 July 2000     

Ultrastructural and Electron Energy Loss Spectroscopy Studies of Sequestration Mechanisms of Cd and Cu in the Marine Diatom Skeletonema costatum

The marine diatom Skeletonema costatum was used to study mechanisms of detoxification when submitted to cadmium and copper contamination. After 96 h of growth, concentration corresponding to 50% growth inhibition (IC₅₀, 96 h) was 0.224 mg/L for cadmium and 0.045 mg/L for copper, indicating that copper is more toxic for S. costatum than cadmium. Heavy cellular damages were observed for cadmium and copper concentrations close to the IC₅₀. Exposure to these concentrations induced a migration of inclusions from the peripheral cytoplasm to the vacuole. Electron energy loss spectroscopy (EELS) investigations demonstrated that Cd and Cu were specifically trapped in these inclusions. However, Cu was less sequestered than cadmium in the vacuole. EELS determination of oxidation states evidenced that trace metals were sequestered as Cd²⁺ and Cu²⁺. Nitrogen and sulfur are involved in metallic storage, especially in the case of cadmium contamination. Received: 6 August 1996/Revised: 18 February 1997     

The pattern of organochlorines in mussels Mytilus edulis L. from the south west Baltic Sea

The concentration of organochlorines (PCB, DDT and its metabolites, HCH isomers and HCB) were determined in mussel, Mytilus edulis from the south west Baltic Sea. The harbor Kiel Innenförde showed the highest contamination with PCB (487 g/kg dry weight), the Gelting bathing beach area the lowest contamination (38 g/kg). The highest contamination with DDT was measured in Lübeck bay, which may be explained by the long term application of DDT in the former German Democratic Republic.Penta- and hexa-chlorinated PCB were selectively accumulated in Mytilus edulis whereas highly lipophilic PCB with more than seven chlorine atoms were found in negligible concentrations. The accumulation of these compounds in mussels is determined by equilibrium partitioning with ambient water.     

Transfer of cadmium in a phytoplankton-oyster-mouse food chain

The trophic transfer of cadmium (Cd) was studied in a phytoplankton-oyster-mouse food chain. Phytoplankton, grown in a continuous culture chemostat system containing CdCl₂ plus the isotope¹⁰⁹Cd, accumulated 70% of the total supplied cadmium. Oysters filtered out 85 to 95% of the phytoplankton. The rate of oyster Cd accumulation at 15 C increased linearly with seawater Cd concentration according to: y=0.066X – 0.15 (n =12, r=0.96); where X=g Cd/L seawater (between 2 and 22) and y=g Cd/g dry wt oyster/ day. About 59% of the Cd accumulated by the oysters came from the phytoplankton food source and 41% from the cadmium dissolved in the water. Sixty-one percent of the total supplied cadmium was retained in the whole soft body of the osyters. Mice fed 0.4 g of oyster-bound Cd per g of diet, retained 0.83% of the dietary cadmium consumed. Mouse kidney retention for organic oyster-bound cadmium was 0.14%. Extrapolation of these results to human risk assessment indicates that moderate consumption of oysters, which are not highly contaminated with cadmium, poses no significant health risk in terms of elevating kidney cadmium levels.     

Filtration and phototactic behavior as indices of chronic copper stress inDaphnia magna straus

Filtration rate and negative phototactic behavior ofDaphnia magna were evaluated as potential predictors of the chronic no-effect copper concentration. The effects of copper on filtration and phototactic behavior were compared to the effects of chronic copper exposure on survivorship, number of juvenile molts, age at reproductive maturity, and neonate body length. Animals exposed to copper concentrations 20g/L exhibited reductions in filtration rate, negative phototaxis, body length of neonates and survival time. Animals exposed to 10g/L exhibited a reduction in filtration rate, negative phototaxis and body length of neonates, but not in survival time. Number of juvenile molts, age at reproductive maturity, and mean brood size each responded erratically to copper exposure and are poor indices of copper stress. Since phototactic behavior, filtration rate, and neonate body length were all reduced at copper concentrations which did not reduce longevity or reproduction, bioassays in which only the latter are examined may underestimate the toxicity of copper and other chemicals. This may occur if bioassays are conducted for the frequently chosen 21-day interval.