Physiological response of the mud crab,Eurypanopeus depressus to cadmium

Although there is an increasing interest in heavy metals as pollutants in the marine environment, relatively little work has been done to determine the effect of such metals on marine organisms (Katzet al. 1971, 1972; Reish 1970, 1971, 1972; Selleck 1970, 1971). Most of these studies have dealt with lethal effects of copper and mercury on fouling organisms (Bryan 1971). Several investigators have reported heavy-metal effects on adult decapod crustaceans (Eisler 1971; Eisleret al. 1972; Raymont and Shields 1964; Vernberg and O'Hara 1972). There is, however, a paucity of information on the effects of cadmium on this group. The present study was undertaken to determine the toxicity of acute exposure of cadmium to the mud crab,Eurypanopeus depressus, as evidenced by mortality and by differential oxygen consumption occurring at non-lethal levels of this contaminant.E depressus was chosen for study because its estuarine habitat is likely to be polluted with heavy metals in the heavily industrialized areas of the Northeast. Cadmium was chosen as the test metal because of the growing awareness of its toxic properties, its persistent nature and its increasing occurrence in the environment. (U. S. Council on environmental quality 1971).     

Observations with Thalassiosira rotula (Meunier) on the toxicity and accumulation of cadmium and nickel

Cadmium and nickel toxicity thresholds based on generation time, maximum cell density, and chain length as toxicity indicators were evaluated from batch cultures of the marine diatom Thalassiosira rotula in nutrient-enriched seawater as substrate. Nickel toxicity is about an order of magnitude or more higher than cadmium toxicity. The toxicity thresholds decrease with increasing illumination and are not significantly affected by 10 μmol/liter EDTA. From the metal accumulation determined by voltammetry average maximum uptakes of 90 μg Ni/g DW and 600 μg Cd/g DW were determined.     

Class III metallothioneins in response to cadmium toxicity in the marine microalga Tetraselmis suecica (Kylin) Butch

Microalgae are one of the most important organisms in our ecosystems being seriously affected by metal pollution. However, the microalgae Tetraselmis suecica (Kylin) Butch is tolerant to cadmium; the concentration of this metal that reduces the population growth to 50% of the control growth level is 5.8 mg/L after 96 h of exposure. In this study, class III metallothioneins were investigated for their involvement as a possible tolerance mechanism in this microalga when exposed to cadmium. A set of these molecules was purified from these microalgal cells after exposure to the metal. These polypeptides were analyzed by capillary zone electrophoresis, which is a technique that allows the length of the metallothioneins synthesized by this microalga to be known. The T. suecica cells were able to synthesize class III metallothioneins of three to six subunits of (gamma-Glu-Cys). The most abundant polypeptide possessed four subunits, and (gamma-Glu-Cys)6-Gly was the largest polypeptide synthesized by this microalga and detected by this technique. Tolerance to cadmium as a function of increasing polypeptide length is also discussed.     

Cadmium content in selected rat tissues following treatments with cadmium chloride and/or gamma radiation

This study was conducted to determine concentrations of cadmium (Cd) in various rat tissues; radiation effectiveness on Cd concentrations in rat tissues; and Cd effectiveness when radiation was applied as the second insult. Animals were subjected to Cd over a 29-day period and on Day 30 were exposed to an acute dose of 60Co gamma-ray. Rats were killed on Day 1, 7, or 21 following irradiation. Cd concentrations were determined by flame spectroscopy. Rats injected with Cd alone or Cd in combination with radiation showed a dose-dependent accumulation and retention of the metal in the liver and kidney over the intervals to sacrifice. Significantly smaller amounts of the metal were seen in the spleen, intestine, stomach, heart, testis, lung, blood, brain, and muscle. Generally, Cd did not afford protection against radiation in the tissues studied. Radiation, when used singly or as a coinsult with Cd, did not significantly alter the concentrations of Cd in any of the tissues studied except the heart, in which it contributed to the clearance of Cd. No synergistic or antagonistic effects were observed between Cd and ionizing radiation in any of the other tissues studied.     

Histopathological alterations in the liver of freshwater teleost Tilapia mossambica in response to cadmium toxicity

The effects of lethal (50 ppm) and sublethal (5 ppm) concentrations of CdCl2 on the liver of the freshwater teleost Tilapia mossambica were studied by routine histological techniques. Engorged blood vessels, congestion, vacuolar degeneration of hepatocytes, necrosis of pancreatic cells, and fatty changes in the peripancreatic hepatocytes were the pathological alterations observed in liver.     

Fluoride-induced changes in carbohydrate metabolism in the tissues of fresh water crab Barytelphusa querini

Exposure of fresh water crab Barytelphusa querini to a sublethal concentration of NaF (30 ppm) caused significant alterations in the carbohydrate metabolism. In an exposure span of 15 days the crab was observed to have marked depletion in glycogen and total free sugar levels. A significant elevation in "active" and "total" glycogen phosphorylase activity was observed. The activity changes of lactate dehydrogenase reflected changes in tissue lactate levels and succinate dehydrogenase activity had a tissue specificity.     

Protective effects of selenium (Se) and zinc (Zn) on cadmium (Cd) toxicity in the liver of the rat: Effects on the oxidative stress

Cadmium (Cd) is a very harmful environmental pollutant that transfers between various levels of the food chain. To study the protective effect of Se and Zn on Cd-induced oxidative stress in livers, male rats received either, tap water, Cd, Cd+Zn, Cd+Se or Cd+Zn+Se in their drinking water, for 35 days. The activities of total superoxide dismutase (SOD), copper, zinc-superoxide dismutase (CuZn SOD), glutathione peroxidase (GPx) and catalase (CAT), malondialdehyde (MDA) level and the ratio of CuZn SOD to GPx activity, were determined in the liver. Exposure to Cd lowered total SOD, CuZn SOD, GPx and CAT activities, while it increased MDA level and the ratio of CuZn SOD to GPx activity, in the organ studied. With Se or Zn administration during exposure to Cd, only partial corrective effects on Cd-induced oxidative stress in the liver have been observed, while Se and Zn together assured a more efficient protection of the organ against the observed oxidative stress.     

Comparing the acute response to cadmium toxicity of nauplii from different populations of Artemia

The lethal responses to cadmium of instar II nauplii from eight populations of Artemia belonging to the species Artemia franciscana, Artemia salina, Artemia persimilis, and Artemia parthenogenetica have been compared. Generalized linear models were used to fit mortality. The model indicates that there is a relationship between species, type of population, and mortality rate. The two populations of A. franciscana were the most sensitive to cadmium toxicity (median lethal concentration, LC50, of 93.3-142 mg/L), while the population of A. persimilis was the most resistant (LC50 of 284 mg/L). Differences in the phenotypic variability in each population were assessed through the slope of the mortality curve, with A. persimilis exhibiting the highest diversity. This study suggests that habitat peculiarities and historical origin of the populations may have a significant influence on their response to cadmium toxicity.     

The toxicological response of the algaAnabaena flos- aquae (cyanophyceae) to cadmium

The toxicological response of the cyanophycean algaAnabaena flos- aquae to cadmium was investigated by three integrated approaches: 1) the determination of the incipient lethal concentration of the metal, 2) study of metal incorporation and cellular compartmentalization using X-ray energy dispersive analysis, and 3) the quantification of intracellular structural changes, after metal exposure, using morphometric analysis. After 96 hr of exposure, the incipient lethal concentration was calculated to be 0.118 ± 0.04 M cadmium. At concentrations three orders of magnitude higher than the incipient lethal concentration, cadmium was incorporated into both the cellular cytoplasm and the cell's polyphosphate bodies. Cadmium also caused the polyphosphate bodies to lose Mg and Ca, resulting in ionic changes in the elemental composition of these cellular inclusions. The utilization of stereological techniques for electron microscopic morphometric analysis established that all concentrations of cadmium tested caused significant reductions in the surface area of the cell's thylakoids. Cadmium induced changes in the numbers and relative volume of the cell occupied by polyhedral bodies, polyphosphate bodies, lipid inclusions, cyanophycin granules, membrane limited crystalline, inclusions, and changes in the volume of the cell wall layers were also documented. The physiological significance of these findings are discussed in terms of the toxic action of cadmium and the cellular mechanisms for detoxification of cations once they enter the cell.     

Acute toxicity of selected pesticides to the Pacific blue-eye, Pseudomugil signifer (Pisces)

Because the larvivorous fish Pseudomugil signifer is native to southeastern Queensland and is abundant in shallow estuarine habitats, intertidal marshes, wetland habitats, and freshwater streams, it was chosen as an indicator species for toxicologic studies with pesticides. Acute toxicity studies with 2 organophosphorus pesticides (pirimiphos-methyl and temephos) and 3 alternate compounds under evaluation for registration in Australia (Bacillus thuringiensis var. israelensis, s-methoprene, and pyriproxyfen), were tested in 96-h laboratory trials. Pirimiphos-methyl was the most toxic compound, with a median lethal concentration (LC50) of 0.091 ppm (0.3 times the estimated field concentration [EFC] for a 15-cm-deep pool). Temephos had an LC50 value of 0.594 ppm (9.9 times the EFC). Bacillus thuringiensis var. israelensis and pyriproxyfen produced LC50 values of 6.1 x 10(11) International Toxic Units (477 times the EFC) and 0.854 ppm (106 times the EFC), respectively. s-Methoprene was the least toxic compound, with no mortality recorded at 500 times the EFC.     

On the terrestrial toxicity of the fungicide imazalil (enilconazole) to the earthworm species Eisenia foetida

The toxicity of imazalil (enilconazole), of its sulfate salt, and of a principal environmental transformation product to the earthworm species Eisenia foetida was determined. The 48-hr contact test and the 14-day artificial soil test as described by OECD guideline 207 were carried out. Concentrations of the parent substance in earthworm tissues at the end of the exposure in soil were determined by gas chromatography. The LC50 of imazalil was 12.8 micrograms/cm2 in the contact test and 541 micrograms/g in the artificial soil test. The LC50 values of the sulfate salt were 11.6 micrograms/cm2 and 532 micrograms/g, respectively. The transformation product had a LC50 of 108 micrograms/cm2 in the contact test, and the survival in the soil test exceeded 90%, even at levels of 1000 micrograms/g. Tissue levels of imazalil in surviving worms were always lower than the concentrations in corresponding soil. The LC50 values largely exceeded the levels expected after normal use. Therefore, the fungicide is not considered to be harmful to earthworms in the soil environment.     

Safety assessment of selected inorganic elements to fry of chinook salmon (Oncorhynchus tshawytscha)

The acute toxicities of arsenate, arsenite, cadmium, chromate, copper, mercury, silver, vanadium, and zinc were determined, individually and in two environmentally relevant mixtures, to two life stages of chinook salmon in reconstituted fresh and brackish waters that simulated potential conditions in the San Joaquin Valley, California. The relative individual toxicities of the elements varied over four orders of magnitude; from most toxic to least toxic, the rank order was cadmium > copper > mercury > zinc > vanadium > arsenite > arsenate > chromate (no definitive tests for silver). In general, young fish tested in fresh water were more sensitive to the individual elements and the two mixtures than were advanced fry tested in brackish water. A 13-element mixture simulating concentrations in the San Luis Drain had the same toxicity to fish as the same mixture plus selenate and selenite, thus demonstrating that the presence of selenium at its environmental ratio in the mixture contributed no toxicity in short-term tests. As judged by a comparison of the individual acute values for salmon to the expected environmental concentrations in the San Luis Drain, the margins of uncertainty for cadmium and copper in both waters, zinc in fresh water, and mercury in brackish water were less than 100, whereas for the two environmental mixtures the margins were less than 15 in both test waters. These low margins of uncertainty, especially for the mixtures, indicate a high potential for environmental hazard to chinook salmon in the reconstituted waters tested.