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  • 1
    Electronic Resource
    Electronic Resource
    Flux of cadmium through euphausiids (1974)
    Springer
    Marine biology 27 (1974), S. 205-212 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Flux of the heavy metal cadmium through the euphausiid Meganyctiphanes norvegica was examined. Radiotracer experiments showed that cadmium can be accumulated either directly from water or through the food chain. When comparing equilibrium cadmium concentration factors based on stable element measurements with those obtained from radiotracer experiments, it is evident that exchange between cadmium in the water and that in euphausiid tissue is a relatively slow process, indicating that, in the long term, ingestion of cadmium will probably be the more important route for the accumulation of this metal. Approximately 10% of cadmium ingested by euphausiids was incorporated into internal tissues when the food source was radioactive Artemia. After 1 month cadmium, accumulated directly from water, was found to be most concentrated in the viscera with lesser amounts in eyes, exoskeleton and muscle, respectively. Use of a simple model, based on the assumption that cadmium taken in by the organism must equal cadmium released plus that accumulated in tissue, allowed assessment of the relative importance of various metabolic parameters in controlling the cadmium flux through euphausiids. Fecal pellets, due to their relatively high rate of production and high cadmium content, accounted for 84% of the total cadmium flux through M. norvegica. Comparisons of stable cadmium concentrations in natural euphausiid food and the organism's resultant fecal pellets indicate that the cadmium concentration in ingested material was increased nearly 5-fold during its passage through the euphausiid. From comparisons of all routes by which cadmium can be released from M. norvegica to the water column, it is concluded that fecal pellet deposition represents the principal mechanism effecting the downward vertical transport of cadmium by this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391945
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  • 2
    Electronic Resource
    Electronic Resource
    Long-Term observations on the moulting frequency of the shrimp Lysmata seticaudata (1980)
    Springer
    Marine biology 59 (1980), S. 219-223 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of body-size and temperature on moulting frequency of the shrimp Lysmata seticaudata Risso were examined under controlled laboratory conditions. Shrimp ranging in weight from approximately 0.4 to 1.14 g and maintained at 17°C exhibited intermoult periods of similar duration (≈20 d). On the other hand, small individuals (0.23 g) held at the same temperature moulted on the average every 14.5 d. Over a temperature range from 8° to 20°C mean intermoult periods were inversely and linearly related to temperature; an increase of 1 C0 resulted in a decrease in the intermoult period of approximately 1.5 d. Although temperature acted to regulate the intermoult period of each shrimp in increments of whole days, it had little effect on the time of moulting within any 24 h period, since moulting occurred more than 93% of the time between 18.00 and 08.00 hrs. The night-time moulting pattern also tended to be most pronounced at lower temperatures (8° and 13°C) and in larger individuals. Possible factors controlling this phenomenon and its occurrence in other crustacean species are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00404744
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  • 3
    Electronic Resource
    Electronic Resource
    Flux of 141Ce through a euphausiid crustacean (1973)
    Springer
    Marine biology 21 (1973), S. 317-325 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The role of the Mediterranean euphausiid Meganyctiphanes norvegica in the cycling of radiocerium (141Ce) was examined. When uptake of 141Ce occurs directly from the water, a “dynamic” population equilibrium is reached at a concentration factor of about 250. Molting was responsible for up to 99% loss of total body burden at first molt, and about 45% of the remaining activity at second molt, thus denying true longterm equilibrium to individual animals. Fecal pellets did not contain measureable 141Ce activity when the euphausiids accumulated the isotope from water, thus proving that surface adsorption was the key accumulating process from water. When radiocerium was taken in through ingestion of labelled Artemia, about 99% of the body burden was voided as fecal pellets. Excretion by this route was accelerated when euphausiids were fed non-radioactive Artemia during loss phase. Radioactive counts of the pellets confirmed that all ingested 141Ce was lost through defecation. When 141Ce was ingested as labelled phytoplankton, a substantial fraction of the total body burden occurred in the molts, which indicated that the phytoplankton lost 141Ce to the water and the radioactivity was subsequently adsorbed to outer surfaces of the euphausiids. Molts, fecal pellets, and freshly-killed euphausiids lost 141Ce to the water exponentially, the rates being similar to the exponential portions of the loss curves for live, non-molting individuals. It is suggested that M. norvegica, and probably other pelagic zooplankters, can greatly accelerate radiocerium transport to the ocean floor by packaging the isotope as fecal pellets. In coastal areas subject to low-level radioactive waste disposal, 141Ce might be ionic (or at least soluble) to a great extent, in which case euphausiids could take up the isotope rapidly and accelerate its vertical transport via molting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381088
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  • 4
    Electronic Resource
    Electronic Resource
    Plutonium and Americium: Uptake from contaminated sediments by the polychaete Nereis diversicolor (1976)
    Springer
    Marine biology 38 (1976), S. 95-100 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polychaete Nereis diversicolor O.F. Müller was exposed to marine sediments which had been contaminated with plutonium and americium either through the testing of nuclear devices or by the release of liquid waste effluent from a nuclear fuel reprocessing plant. The uptake of both plutonium and americium was small, about 0.5% of the concentration of these transuranics in the sediments. The degree of relative uptake of plutonium from both sediments was comparable; relative uptake of americium from sediments contaminated by waste effluent was greater than that from nuclear sediment and those previously determined from water-uptake experiments to environmentally determined plutonium concentrations in sediments and overlying waters leads to the tentative conclusion that water may be the predominant pathway for plutonium accumulation by deposit-feeding worms like N. diversicolor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00390762
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  • 5
    Electronic Resource
    Electronic Resource
    Factors affecting the flux of arsenic through the mussel Mytilus galloprovincialis (1979)
    Springer
    Marine biology 51 (1979), S. 209-219 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Radiotracer experiments were designed to study the effects of certain environmental and biological factors on arsenic accumulation and elimination processes in the Mediterranean mussel Mytilus galloprovincialis. Arsenic (as arsenate) uptake increased with increasing arsenic concentration in the water; however, the response was not proportional, indicating that accumulation was partially suppressed at higher external arsenic concentrations. In general, approximately 80% of the 74As taken up was associated with the soft parts, with small mussels concentrating 74As to a greater degree than larger individuals. The highest 74As concentrations were recorded in the byssus and the digestive gland. Increased temperature enhanced both arsenic uptake and loss. Mussels in sea water at 19‰ S accumulated approximately three times more 74As than those held at 38‰ S. Arsenic loss was much less affected by salinity, with only a tendency for greater arsenic retention noted at lower salinities. Studies carried out in the laboratory and in situ revealed that arsenic turnover was significantly more rapid in actively growing individuals living under natural conditions. Arsenic-74 loss from the in situ group was essentially biphasic, with biological half-times of approximately 3 and 32 days for the fast and slow compartments, respectively. The active secretion of arsenic in the byssal threads contributed to the total elimination of the element from the mussels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386800
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  • 6
    Electronic Resource
    Electronic Resource
    Uptake of 55Fe from contaminated sediments by the polychaete Nereis diversicolor (1980)
    Springer
    Marine biology 56 (1980), S. 277-280 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polychaete Nereis diversicolor O. F. Müller was exposed to marine sediments which had been contaminated with 55Fe either through the testing of nuclear devices or by the release of liquid waste effluent from a nuclear fuel reprocessing plant. The amount of 55Fe taken up reached a concentration in the worms about 6% of the concentration in both types of sediment. Bioavailability of 55Fe was shown to depend on its concentration in sediment and not on sediment type, stable iron concentration, or the source of contamination. N. diversicolor may not extract from sediment the same fraction of 55Fe as does 0.1N HCl and caution should be exercised in using such measurements to represent the bioavailable fraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386865
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  • 7
    Electronic Resource
    Electronic Resource
    Vanadium transfer in the mussel Mytilus galloprovincialis (1980)
    Springer
    Marine biology 56 (1980), S. 281-293 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Radiotracers were used to study processes controlling the accumulation and elimination of vanadium in the Mediterranean mussel Mytilus galloprovincialis. Vanadium uptake rates varied inversely with both salinity and vanadium concentration in water, but were independent of temperature. After a 3 wk exposure to 48V, the highest concentration factors were found in the byssus (≈1900) with much lower values computed for shell (≈ 70) and soft tissues (≈5). More than 90% of the total 48V accumulated was fixed to shell, suggesting that uptake is primarily a result of surface sorption processes. Much of the vanadium in shell was firmly bound to the periostracum and was not easily removed by acid leaching. Food-chain experiments indicated that the assimilation coefficient for ingested vanadium is low (≈7%) and that the assimilated fraction is rapidly excreted from the mussel. These findings coupled with knowledge of in situ and experimentally-derived vanadium concentration-factors have allowed a preliminary assessment of the relative importance of the food and water pathways in the contamination of mussels under conditions of acute and chronic exposure. Contaminated mussels transferred to clean sea water lost 48V at rates that depended upon temperature but were largely unaffected by either salinity or by vanadium levels in mussel tissues. Total vanadium depuration was slow and was governed by loss from a slowly-exchanging compartment with a characteristic half-time of about 100 d. Individual mussel tissues were analyzed for stable vanadium and the possibility of using these tissues, particularly the byssus, as bioindicators of ambient vanadium levels in the marine environment is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386866
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  • 8
    Electronic Resource
    Electronic Resource
    Intracellular localization and binding of technetium-95m in the seastar Marthasterias glacialis (1985)
    Springer
    Marine biology 85 (1985), S. 43-50 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The subcellular distribution of technetium was studied using the seastar Marthasterias glacialis which had previously ingested prey labelled with 95mTc either as pertechnetate (VII) or in the reduced state (IV). The majority of the Tc [98% (IV) and 96% (VII)] was taken up and retained in the pyloric caeca, the gland responsible for digestive and food storage processes. Differential centrifugation and separation techniques have demonstrated that, at the subcellular level, technetium in the pyloric caeca was largely associated with the lysosomes. 95mTc (IV) was distributed between the lysosomes and the soluble fraction to roughly the same degree, whereas pertechnetate was more strongly associated with the lysosomal fraction. Chromatography of the cytosol by gel filtration indicated the presence of two distinct protein compounds which were responsible for binding virtually all of the technetium in the soluble fraction. Technetium had a greater relative affinity for the low molecular weight compound, more so for Tc (VII) than for Tc (IV). This anionic protein had an apparent molecular weight of approximately 10 000, and thus may play a role in metal detoxification mechanisms at the cellular level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00396413
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  • 9
    Electronic Resource
    Electronic Resource
    Experimental studies on elimination of zinc-65, cesium-137 and cerium-144 by euphausiids (1971)
    Springer
    Marine biology 8 (1971), S. 224-231 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The elimination of 3 radionuclides from Euphausia pacifica was measured over a 5 month period. The biological half-lives for 65Zn, 137Cs, and 144Ce, calculated after the euphausiids had ingested radioactive Artemia nauplii, were found to be 140 days, 6 days, and 7.5 h, respectively. The percentages of body burdens lost in molts were greatest for the fission products, 144Ce (21%) and 137Cs (7%), and least for 65Zn (1%). Elimination of the isotopes in the feces could not be followed because of the difficulty in collecting fecal material for analysis; however, 1 sample collected 2 months after the beginning of the elimination experiment had no measurable radioactivity. Loss of 65Zn from molts and time to disintegration of the molts were found to be temperature dependent over a 5° to 15°C range, and the sinking rate of molts was both temperature and salinity dependent. Calculations showed that, in areas in the North Pacific outside the influence of upwelling, percentage 65Zn loss from sinking molts (before disintegration of the molts) was likely to be the same throughout the year, since the molts would be exposed to about the same mean temperature in the water column in all seasons. Even though temperature structure in the upper layers changes with season, mean temperatures change very little when calculated over the sinking distance of intact molts. Intact molts would sink to slightly over 400 m in the absence of turbulence, and would lose 87% of their 65Zn by the time they reached this depth. Sinking molts thus might contribute substantially to the vertical transport of 65Zn in the sea. If loss of 65Zn in fecal pellets is assumed to be small under our experimental conditions, and molting loss is only 1% of 65Zn body burden, the major mechanism of 65Zn loss from euphausiids feeding on non-radioactive food must be isotopic exchange with the water. Approximately 96% of the initial body burden was eliminated over a period of 5 months.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00355220
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  • 10
    Electronic Resource
    Electronic Resource
    Tissue and subcellular distribution of 252Cf and 241Am in the seastar Marthasterias glacialis (1983)
    Springer
    Marine biology 75 (1983), S. 253-259 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seastars, which are known to accumulate transuranium nuclides to relatively high levels, were used in laboratory radiotracer experiments (April–May, 1982) designed to determine the subcellular distribution of tissue-incorporated californium-252 and americium-241. Mediterranean asteroids (Marthasterias glacialis), collected in April 1982 and fed prey contaminated with 252Cf and 241Am, accumulated and retained large fractions of these radionuclides (252Cf, 91 to 98%; 241Am, 82 to 88%) in their pyloric caeca, the glandular complex involved with digestive and food storage processes. Differential centrifugation demonstrated an association of 252Cf and 241Am with the lysosome-mitochondrial fraction of plyoric caeca cells. Partial separation of lysosomes and mitochondria by isopycnic gradient centrifugation suggests a somewhat different subcellular fractionation of the two transuranics; 252Cf is associated primarily with the mitochondria, whereas 241Am is accumulated in both lysosomes and mitochondria. From comparison with analogous studies in mammalian systems, it is hypothesized that the long biological half-lives reported for ingested transuranics in seastars result in large part from the radionuclide association with mitochondria in the pyloric caeca.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00406010
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