Effect of cadmium on survival and osmoregulation of various developmental stages of the shrimp Penaeus japonicus (Crustacea: Decapoda)

The object of this study was to evaluate the acute toxicity of cadmium in different post-embryonic stages of the penaeid shrimp Penaeus japonicus (Bate, 1888) and to determine the effect of sublethal cadmium on the osmoregulatory capacity used as an indicator of physiological condition. Tolerance to cadmium increases with the developmental stage. The least tolerant stages are the nauplii (48 h LC₅₀: 124 g Cd l^-1) and the zoeae (96 h LC₅₀: 10 to 30 g Cd l^-1). The most tolerant stages are the postlarvae (96 h LC₅₀: 200 to 3500 Cd l^-1) and juveniles (96 h LC₅₀: 5500 g Cd l^-1). In juvenile shrimp, 2000 g Cd l^-1 significantly reduce hypo- and hyper-OC. The effect of cadmium on hypo- and hyper-osmoregulatory capacity illustrates a dose- and time-dependent response. Surviving shrimp recover their hypo-osmoregulatory capacity after 6 d of readaptation in cadmium-free seawater.     

Effects of a dimethylnaphthalene-contaminated food source and daily fluctuating temperatures on the survival potential of the estuarine shrimp Palaemonetes pugio

The biological effects of a naturally occurring perturbation were compared with one which may be induced by man's activities in the coastal zone. The estuarine shrimp Palaemonetes pugio was exposed for 32 d to fluctuating (18°–22°C) temperatures (FT) and/or 2,6-dimethylnaphthalene (DMN)-contaminated food at a concentration of 0.24 g DMN g^-1 wt food. After exposure, relative survival rates were evaluated in a matrix of environmental challenge tests. Low salinity (2 S) had little overall effect on survival. Survival at elevated temperatures (33°C) was significantly lower than in reduced salinity and was independent of the treatment effects. Resistance to the challenge of hypoxia+reduced salinity, however, in contrast to the other tests, was significantly reduced by exposure to FT and DMN-contaminated food. The influence of FT was much stronger and obscured the effects of DMN-contaminated food when shrimp were exposed to both perturbations at the same time. The persistent, residual effects of FT and DMN-contaminated food on the survival of P. pugio during exposure to hypoxia were evaluated after a 16-d recovery period with stable temperatures and uncontaminated food. The initial deleterious effects of FT appeared to be ameliorated by the stable temperatures. On the other hand, shrimp which had ingested DMN-contaminated food, prior to the clean food, exhibited enhanced survival during exposure to hypoxia. After ingesting contaminated food for 32 d, P. pugio contained concentrations of DMN approximately 1 order of magnitude greater than that in the food. Shrimp kept in FT generally had higher concentrations of DMN than shrimp held in stable temperatures. Feeding uncontaminated food to contaminated shrimp for 16 d resulted in a significant reduction of DMN in the tissues.Virginia Institute of Marine Science Contribution No. 983     

Effects of copper and cadmium on growth,swimming and predator avoidance in Eurytemora affinis (Copepoda)

In this study we demonstrate the sensitivity of swimming behavior and predator-escape responses of nauplii of the estuarine copepod Eurytemora affinis to sublethal doses of Cu and Cd. Behavior was generally altered at metal doses below those affecting growth rates or survival of the copepods. Swimming velocities of Cu-dosed nauplii were different from controls at all concentrations of Cu tested (10–50 g l^-1 total Cu) after 24- to 48-h exposure, whereas development rate of nauplii was significantly reduced only after 96 h at 25 g l^-1. The 96 h LC50 for Cu was approximately 30 g l^-1 Cu. Naupliar swimming velocity was also affected by Cd. Swimming speeds were reduced after 24 h at 130 g l^-1, and development was slowed after 48 h at 116 g Cd l^-1. The 96-h LC50 was >120 g l^-1. Little is known of the adaptive role of specific motile behaviors in the success of larval copepods. We investigated the relationship of swimming speed to predator — prey interactions of the nauplii using both real and simulated predators. Nauplii exposed to Cu for 24 h were observed to be generally hyperactive, a condition which could increase their encounter frequency with predators. Reduced numbers of escape responses of nauplii to a simulated predator, another indication of increased vulnerability to predation, were observed only after 48-h exposure to Cu. Nevertheless, feeding rates of non-dosed larval striped bass on dosed nauplii (24 h at 25 g Cu l^-1) were significantly higher than on control nauplii. Feeding rates of larval mysid shrimp, however, were not higher on similarly dosed nauplii; 24 h exposure of nauplii to >30 g Cu l^-1 did result in increased predation by mysids.Contribution No. 272 of the US EPA Environmental Research Laboratory, Narragansett, Rhode Island 02882, USA     

Seasonal abundance,distribution and growth of postlarval and juvenile grass shrimp (Palaemonetes pugio) in a Georgia,USA, salt marsh

Postlarval and juvenile grass shrimp (Palaemonetes pugio Holthuis) ≦15 mm total length (TL) were abundant at low tide in shallow aquatic microhabitats (i.e. puddles and films of residual tidal water) in the intertidal zone of a salt marsh on Sapelo Island, Georgia, USA from 1982 to 1984. The highest concentrations of young P. pugio occurred at 190 to 200 cm above mean low water, ∼10 to 20 cm below mean high water. The intertidal distributions of young grass shrimp expanded and contracted with changes in tidal amplitude. Postlarval grass shrimp (6 to 8 mm TL) continuously recruited into the intertidal marsh population from May until October, but densities varied in a regular pattern with peaks in abundance occurring at ∼2-week intervals, corresponding to spring tide periods in the lunartidal cycle. Although present nearly year-round in the intertidal marsh, juveniles (9 to 15 mm TL) were most abundant from August to October. Apparent growth rates of individuals up to 15 mm TL averaged 0.268±0.026 (mean±95% C.I.) mm d^-1 from May to October and 0.070±0.032 mm d^-1 in November and December. Unlike larger aquatic organisms, which can forage in the emergent marsh only when it is flooded by the tide, juvenile grass shrimp have constant access to intertidal resources. Although potentially important predators in this system, the role of young P. pugio in the trophic organization of salt marsh benthic invertebrate assemblages has yet to be examined. Contribution No. 576 of the University of Georgia Marine Institute     

Effects of kelthane on the estuarine shrimp Crangon tranciscorum

The chlorinated hydrocarbon pesticide Kelthane was assayed for effects on food consumption, molting rate, cannibalism, respiration, mortality and behavior of the estuarine shrimp Crangon franciscorum Stimpson. The test system was a single-pass pulse-flow apparatus employing a modified Mount-Brungs style diluter. Treatment levels were 0, 14, 33 and 81 g l^-1 Kelthane at 16.6°C and 19 S over an exposure period of 317 h. Exposure to Kelthane reduced food consumption, molting rate, cannibalism, and respiration. Behavior also was abnormal in exposed shrimp. They spent more time swimming, were less coordinated and had feeble escape reactions. Kelthane was very toxic to C. franciscorum with LT₅₀ values of 163, 196 and 264 h for shrimp exposed to 81, 33 and 14 g l^-1 respectively. The incipient lethal level of Kelthane is probably below 14 g l^-1.     

Prolonged exposure to low dissolved oxygen affects early development and swimming behaviour in the gastropod Nassarius festivus (Nassariidae)

Effects of low dissolved oxygen on early development and swimming behaviour of veliger larvae of the scavenging gastropod Nassarius festivus were studied. Embryonic development was significantly delayed when dissolved oxygen level was reduced to 3.0 mg O₂ l⁻¹ and no embryo hatched successfully at 0.5 mg O₂ l⁻¹. Veliger larvae hatched at 4.5 mg O₂ l⁻¹ had significantly smaller velar lobe, shell length and shell width. Median 48-h LC₅₀ value of the veliger larvae was estimated at 1.25 mg O₂ l⁻¹ with lower swimming speed (swimming velocity and dispersal velocity) being recorded for the survivors exposed to reduced oxygen levels. The percentage of veliger larvae that developed into crawling juveniles was significantly reduced and metamorphosis was delayed at 4.5 mg O₂ l⁻¹ whereas all larvae at 3.5 mg O₂ l⁻¹ died before they underwent metamorphosis. Juveniles developed at 4.5 mg O₂ l⁻¹ were also smaller than those at 6.0 mg O₂ l⁻¹. Results indicated that dissolved oxygen levels well above hypoxia levels (2.8 mg O₂ l⁻¹) have already had significant impact on the hatching success and larval development in gastropods, which may lead to long-term decreases in population growth.     

Cadmium accumulation,LC50 and oxygen consumption in the tropical marine amphipod Elasmopus rapax

Adult Elasmopus rapax, collected from the eastern coast of Venezuela in 1990, were exposed to seawater containing various CdCl₂ concentrations ranging from 0.25 to 5.5 mol l^-1. The 48-h and 96-h LC₅₀ values obtained were 4.0 and 1.6 mol Cd l^-1, respectively. In amphipods exposed to 1 mol Cd l^-1 for up to 240 h, the apparent rate of cadmium uptake was higher in dead animals (most of which had molted during the preceding 24 to 48 h) than in those which survived throughout the treatments without molting. Thus, whole-body cadmium content reached 1.74 mol g^-1 dry weight (dw) in the former and only 0.85 mol g^-1 dw in the latter; the higher body Cd-load may have caused the increased mortality observed in molters. On exposure to cadmium levels above 0.5 mol l^-1 the oxygen consumption rate of non-molters decreased from 2.2 to about 1.5 ml O₂ g^-1 dw h^-1 over the first 24 h, remaining unchanged thereafter. The results place E. rapax among the most sensitive marine organisms yet studied concerning cadmium toxicity, and emphasize the usefulness of the Amphipoda as bioindicators and research tools for bioassays.     

土壤Cd污染对跳虫Folsomia candida的生态毒性

采矿及冶炼等行为造成了严重的土壤重金属污染,其中Cd污染及其带来的健康风险近年来引起人们的高度重视。利用弹尾目跳虫开展土壤Cd污染的生态毒理研究,对Cd污染土壤的生态风险评价具有重要意义。本研究将跳虫Folsomia candida(F.candida)暴露在不同Cd浓度污染的人工土壤中,利用跳虫存活数量、繁殖数量及回避行为实验来评价重金属Cd污染对跳虫的生态毒性。结果表明,Cd对F.candida的急性毒性LC50值为2 086.93 mg·kg~(-1),慢性毒性的繁殖抑制(28 d)EC50值为224.95 mg·kg~(-1)。此外,Cd对跳虫回避行为影响的EC50(48 h)为721.26 mg·kg~(-1)。可以看出,慢性毒性的EC50值与Cd对回避行为影响的EC50值近似,但远低于急性毒性LC50值。因此,跳虫F.candida的回避行为和繁殖率对Cd污染土壤有较高的灵敏度,可用来表征土壤中Cd的生态毒性。     

Effect of copper on ion- and osmoregulation in the shore crab Carcinus maenas

The uptake and effect of dissolved copper on regulation of hemolymph osmolality and Na⁺, K⁺, Cl^-, Ca⁺⁺, and Mg⁺⁺ concentrations in the shore crab Carcinus maenas (L.) were determined at 400 mOsm (=14 S) ambient salinity. One mg Cu l^-1 resulted in 50% mortality in 11 to 22 d; the highest sensitivity was observed around the moulting period. 0.25 and 0.5 mg Cu l^-1 were not lethal after a onemonth exposure. Ten, 1, and 0.5 mg Cu l^-1 altered regulation of osmolality, Na⁺, K⁺, and Cl^- concentrations, while 0.25 mg Cu l^-1 did not. Exposure to 1 mg Cu l^-1 reduced hemolymph osmolality and Na⁺, K⁺, and Cl^- concentrations to 80 to 90% of controls within 4 to 6 d and no further reduction was observed during a 21-d exposure. The effect of various copper concentrations on these four parameters were almost identical and the highest sensitivity was observed around the moulting period. Hemolymph calcium levels increased 20 to 80% in crabs exposed to 1 mg Cu l^-1, while they decreased 20 to 30% in crabs exposed to 0.5 mg Cu l^-1. Prolonged exposure to copper caused 20 to 70% reductions in hemolymph magnesium levels. Crabs exposed to 0.5 mg Cu l^-1 for 29 d accumulated copper in hepatopancreas, gills, carapace, heart, testes, and hypodermis, but not in muscles and hemolymph. Increased copper levels in crabs exposed to 0.25 mg Cu l^-1 were observed in hepatopancreas, gills, and carapace only. The present results suggest that effects of copper on ion regulatory processes in part explain why the toxicity of copper towards euryhaline invertebrates increases at low salinities.     

Observations of the effect of zinc on the gametes and various development phases of Arbacia lixula

The action of various concentrations of zinc on different phases of development of Arbacia lixula L. has been observed. The following concentrations were used in the experiment: 0.01, 0.1, 1 and 10 mg l^-1; these concentrations were tested on unfertilized eggs, sperms, fertilized eggs and adult individuals. It was found that after 96 h a 0.01 mg l^-1 concentration reduces the mobile sperm percentage compared with the control group. At concentrations of 0.1, 1 and 10 mg l^-1 no mobile sperm were found after 96 h. Compared with the control group, the action of zinc on unfertilized eggs was to increase the percentage of eggs showing signs of cytolisis after 12, 36 and 60 h. In the case of fertilized eggs it was found that with a concentration of 0.01 mg l^-1 the P₅ pluteus stage was attainable; the percentage of forms reaching that stage was less than in the control group. At 0.1 mg l^-1 only a very low percentage of eggs could reach the P₅ pluteus stage; concentrations of 1 and 10 mg l^-1 are incompatible with the normal development of an egg. Adult individuals kept in aquaria with 1 mg l^-1 zinc showed no signs of suffering after 20 d. Gametes are proposed as the appropriate material for carrying out bioassays.     

Accumulation of cadmium from contaminated water and sediment by the shrimp Callianassa australiensis

The burrowing marine shrimp Callianassa australiensis (Dana) was collected from an uncontaminated area in Western Port, Victoria, Australia in 1977. The shrimp were exposed to cadmium-contaminated water and sediment for 8 wk. The concentrations ranged from 0.5 to 63 g Cd 1^-1 for water and 0.5 to 63 g Cd g^-1 for sediment. The shrimp accumulated cadmium from water at a rate commensurate with increases in the concentration of cadmium in water and the duration of the experiment. Although the cadmium concentration in the sediments was 10³ times higher than that in water, it hat no effect on cadmium uptake by the shrimp. The concentration factors decreased with increasing concentration of cadmium in water but increased as the duration of exposure increased. The shrimp dry weight decreased with increasing concentration of cadmium in water and duration of exposure. As was the case with cadmium uptake by the shrimp, these two factors acted interactively on the shrimp dry weight, but the third factor, concentration of cadmium in sediment, had no effect.     

The effect of low concentrations of phenol and ammonia on egg production rates,fecal pellet production and egg viability of the calanoid copepod Acartia clausi

Estimates of daily fecundity, hatching success and fecal pellet production are reported for Acartia clausi females exposed for 10 d to low levels of phenol and ammonia. Copepods were collected in 1991 and 1992 from a southern coastal area of the Mar Grande of Taranto (southern Italy). A reduction in egg numbers and fecal pellet production was observed for females after 8 d of exposure to 500 g l^-1 phenol concentration. Ammonia (120 g l^-1) produced a significant increment in egg production, but hatching success was reduced by about 50% after nine exposure days. A. clausi was more sensitive to ammonia than phenol at high concentrations (24-h LC₅₀ phenol-32.26 mg l^-1; 24-h LC₅₀ ammonia=0.91 mg l^-1). At low concentrations, only long-term exposure to phenol determined a reduction in fecundity.     

Fluxes of dissolved and particulate calcium in selected tissues of Crassostrea virginica

Rates of calcium incorporation by selected tissues of Crassostrea virginica increased in a step-wise fashion from lowest values among organisms exposed to ambient total calcium concentrations of 45 mg l^-1, intermediate values among oysters exposed to 135, 225, and 315 mg l^-1, to highest rates for oysters exposed to 360 mg l^-1. Although excised visceral mass tissue had highest rates of calcium incorporation relative to mantle, muscle, and both organic and inorganic portions of the shell, mantle tissue appeared to have the most dynamic response to changes in ambient calcium concentrations. Rates of dissolved calcium incorporation from ambient water were approximately two to three orders of magnitude higher than comparable rates from ingested algal food. Behavioral response to concentrations of selected inoic, species in the ambient environment may have been responsible for observed differences in rates of calcium incorporation.     

Sediment-induced reduction in the pumping rate of the tropical sponge Verongia lacunosa

The pumping rate of Verongia lacunosa (Lamarck), a tropical marine sponge, varied between 1 and 6 l h^-1 in clear seawater for sponges with a volume of about 500 ml. Sponges were exposed to seawater containing suspensions of clay maintained at a constant level for 4 h; concentrations of 11 mg l^-1 or greater significantly reduced the pumping rate, while concentrations of 3 mg l^-1 did not. Other sponges were exposed to suspensions of clay for 4 days; a concentration of 95 mg l^-1 caused a continuing decline in the pumping rate. These sponges were more sensitive to sediment than some other suspension-feeding organisms. Such sensitivity may limit the distribution of V. lacunosa and other sponge species.Please address requests for reprints to A.O. Flechsig at the address shown above.     

Effect of ammonia on survival and osmoregulation in different life stages of the lobsterHomarus americanus

Acute toxicity of ammonia was determined for cultured larval, postlarval, and wild adult lobsters (Homarus americanus) in 1988. Ammonia tolerance was found to increase with ontogenetic development. Based on 96-h LC₅₀ values of 58 mg l^–1 NH₄ ⁺ + NH₃ l^–1 seawater (0.72 mg NH₃ l^–1) for Stage I larvae, 87 mg NH₄ ⁺ + NH₃ l^–1 (1.7 mg NH₃ l^–1) for Stage II larvae, 125 mg NH₄ ⁺ + NH₃ l^–1 (2.13 mg NH₃) for Stage III larvae, 144 mg NH₄ ⁺ + NH₃ l^–1 (2.36 mg NH₃ l^–1) for Stage IV postlarvae, 377 mg NH₄ ⁺ + NH₃ l^–1 (5.12 mg NH₃ l^–1) for adult lobsters at 5°C and 219 mg NH₄ ⁺ + NH₃ l^–1 (3.25 mg NH₃ l^–1) for adult lobsters at 20°C, recommendations for safe levels of total ammonia and un-ionized ammonia were calculated using an application factor of 0.1. Effects of ammonia on osmoregulatory capacity were studied on postlarvae and adults. Ability of postlarvae and adults to hyper-regulate in low-salinity media decreased after exposure to ammonia. In postlarval lobsters, osmoregulatory capacity was significantly affected in ammonia concentrations exceeding 32 mg l^–1. Osmoregulatory capacity in adult lobsters (5 and 20°C) was affected at 150 mg l^–1. In postlarval lobsters, a minimum exposure time of 12 h was required to impair osmoregulatory capacity. The decrease in hemolymph osmotic pressure was caused by lower hemolymph sodium concentrations. The presence of ammonia in the external medium could markedly affect the Na⁺/NH₄ ⁺ transport mechanism by permanently, temporarily, or partially impairing the transport sites for sodium.     

Unbalanced growth of Acinetobacter CS 13 in glucose-limited chemostats caused by sublethal CdCl2 concentrations

The marine cadmium-sensitive Acinetobacter CS 13 was grown in glucose-limited chemostats to study the chronic toxicity of CdCl₂. Addition of 25, 50 or 100 μg Cd²⁺ l^-1 caused disturbances of balanced growth. At the dilution rate (D) of 0.05 h^-1 the washout rate (A) became constant at 84, 78 or 66 h after addition of 25, 50 or 100 μg Cd²⁺ l^-1 The washout rates were calculated to be respectively 0.037 h^-1, 0.039 h^-1 and 0.077 h^-1. At D=0.1 h^-1, A became constant after 48, 42 and 36 h, and were the same as D for all three Cd concentrations. Acridine orange staining revealed that 99% of the cells fluoresced green (viable cells) and 1% red or orange (dead cells). However, under Cd stress the percentage of red and orange fluorescing cells increased up to 20%. At D=0.1 h^-1, viable and direct cell counts always gave the same result. At D=0.05 h^-1, however, viable cell counts were lower than direct cell counts after 2–3 d of Cd exposure. It is assumed that at D=0.05 h^-1, a part of the cells appearing green was already Cd injured, but the true yellowish green colour was not identified. Decreasing cell densities were accompanied by increasing glucose concentrations. Cells accumulated Cd (0–25 μg Cd²⁺ l^-1) in relation to exposure time and Cd concentration in the medium, but maximum Cd contents were the same, increasing from 5.5 or 5.7 μg g^-1 dry wt in the control to 15 μg g^-1 after 2–3 d (D=0.05 h^-1) or 16 μg g^-1 after 1–2 d (D=0.1 h^-1).     

Osmoregulation of the grass shrimp Palaemonetes pugio exposed to polychlorinated biphenyls (PCBs). I. Effecton chloride and osmotic concentrations and chloride-and water-exchange kinetics

Grass shrimp, Palaemonetes pugio, were capable of hypo- and hyper-osmotic regulation of body fluids. Hemolymph chloride and osmotic concentrations were maintained at relatively stable levels over a wide salinity range. Following an abrupt transfer from intermediate (14 and 17) to high (31 and 35) or low (1 and 2) salinities, hemolymph chloride levels exhibited initial overshoot and undershoot, respectively, of new steady-state levels. Osmotic concentrations exhibited an initial undershoot at low, but not overshoot at high salinity. Chloride space in salinity-acclimated shrimp was relatively stable at salinities from 1 to 35. Changes in chloride space following salinity transfer paralleled those of hemolymph chloride levels, and are discussed in the light of alterations in intracellular sodium concentrations reported earlier. Rate constants for chloride turnover indicated independent exchanges of sodium and chloride ions. Water-turnover measurements showed that permeability of P. pugio was greatest at the isosmotic salinity (17) and reduced at salinities which were associated with active osmoregulation. Exposure to sublethal and 96-h LC₅₀ levels of Aroclor^® 1254 did not seriously alter hemolymph chloride and osmotic concentrations, chloride space or chloride-exchange kinetics in adult shrimp. Disruption of hemolymph chloride regulation in juvenile shrimp was associated with large mortalities not observed in adults. Shrimp exposed to Aroclor 1254 at 17 S exhibited reduced water permeability similar to levels previously observed in controls at high and low salinities in response to osmotic or ionic gradients. Exposure to PCBs did not result in further reduction in permeability at the latter salinities.     

Lethal effects of ammonia and nitrite onPenaeus chinensis juveniles

Juveniles of the prawnPenaeus chinensis (3.96 ±0.18 cm, 0.36±0.06 g) reared in Taiwan in 1989 were exposed to different concentrations of ammonia and nitrite, by a static renewal method in 33 seawater at pH 7.94 and at 26 °C. The 24, 48, 96 and 120 h LC₅₀ (median lethal concentration) of ammonia were 3.29, 2.10, 1.53 and 1.44 mg l^–1 for NH₃-N (un-ionized ammonia as nitrogen) and 79.97, 51.14, 37.00 and 35.09 mg l^–1 for ammonia-N (un-ionized plus ionized ammonia as nitrogen). The 24, 96, 120, 144 and 192 h LC₅₀ of nitrite-N were 339, 37.71, 29.18, 26.98 and 22.95 mg l^–1. The LC₅₀ decreased with increasing exposure time. During the first 96 h,P. chinesis juveniles were more susceptible to ammonia than nitrite. However, prawns were less tolerant to nitrite than ammonia when exposed for more than 96 h. The threshold was found at 120 and 192 h for ammonia and nitrite, respectively, on the toxicity curves. Incipient LC₅₀ was 1.44 mg l^–1 for NH₃-N, 35.09 mg l^–1 for ammonia-N and 22.95 mg l^–1 for nitrite-N. The safe value forP. chinensis juveniles was 0.14, 3.51 and 2.30 mg l^–1, respectively.     

Osmoregulation of the grass shrimp Palaemonetes pugio Exposed to polychlorinated biphenyls (PCBs).

Glycine was the most abundant free amino acid (FAA) in abdominal muscle of grass shrimp Palaemonetes pugio, accounting for over 50% of the total pool. Arginine, alanine, proline, taurine and serine were also present at relatively high concentrations. Following transfer from 17%. to 2 and 32%. S, new steady-state levels of total FAA were observed at 72 h. Total FAA and the sum of glycine, alanine and proline exhibited a positive correlation with salinity. Exposure to Aroclor 1254 did not have appreciable effects on total FAA levels, indicating that disruption of intracellular osmoregulation was not a major consequence of PCB toxicity. However, changes in individual amino acid concentrations in exposed shrimp were reflective of an altered metabolic state. Glycine, which did not show changes immediately following exposure, underwent large decreases after transfer to PCB-free water and indicated a delayed effect of PCB exposure. A correlation between salinity and the sum of glycine, alanine and proline did not exist in exposed shrimp.     

Hematoxicity and hepatoxicity attributed to zinc and cadmium in the Norwegian rat

This study was carried out to determine changes in the blood and liver of rats given oral doses of cadmium (Cd) and zinc (Zn). Thirty 3 month old rats were kept six to a compartment in a well-demarcated five compartment cage labeled A, B, C, D, and E. After 2 weeks of acclimatization, and with ad libitum administration of water and feed, group A and B rats were, respectively, exposed to 100 mg CdSO₄ and 2200 mg ZnSO₄, respectively, mixed with their feed. Group C rats were fed with a combination of 100 mg CdSO₄ and 2200 mg ZnSO₄ mixed with their feed, while group D rats were exposed to 100 mg CdSO₄ mixed with their feed for 48 h, and after they were given 2200 mg ZnSO₄ for 96 h. Group E rats served as control and were fed a normal diet. Analysis of blood samples after 5 days showed that in rats of groups A, B, C, and D, WBC count increased from 6800 to 12,400 mm^?3 and platelets from 26,000 to 88,000 mm^?3. Reduction in blood counts were found for RBC from 13.8 to 4.7 × 10⁶ mm^?3, hemoglobin from 15.6 to 11.4 dL^?1, and PCV from 47 to 34%. ESR was the same 1.0 mm h^?1 in all groups. Severe damage to the liver was also shown by severe degeneration of hepatocytes and increase in Kuppfer cells. The above observations were mildest in the liver of group C rats. A reduction of body weight was observed in all treatment groups. Cd and Zn were found to be hematoxic and hepatotoxic in the Norwegian rat with Cd exhibiting greater toxicity than Zn. Toxicity of Cd was suppressed by Zn only when both metals were admistered at the same time, but a delay in intake of Zn (after 48 h) had little effect on Cd toxicity.