Median Tolerance Limit Research Articles

Long-term effects of water-soluble fractions of Kuwait crude oil on the larval and juvenile development of the mud crab Eurypanopeus depressus

Larvae of the mud crab Eurypanopeus depressus (Smith) were reared in various concentrations of the water-soluble fraction of Kuwait crude oil. The 48-h TLm (median tolerance limit) for Zoea Stage I was approximately 10 ppm total dissolved hydrocarbons and that for Zoea Stage II approximately 17 ppm. Chronic toxicity of more dilute solutions (4.3 and 8.7 ppm) was assessed independently for each larval stage and for subsequent developmental stages through Crab Stage 5. In the group continuously exposed to oil from hatching, there was differential mortality relative to controls in every larval stage and increased duration of intermolt periods was observed at every stage through Crab Stage 5. Mortality in groups not exposed until larvae had reached Zoea Stages III or IV was not greater than controls, suggesting that toxicity to advanced larval stages may be related to accumulation of toxic compounds by the larvae. Neither concentration (4.3 or 8.7 ppm) of crude oil caused increased mortality among juvenile crab stages regardless of the time of initial exposure. Increased occurrence of an extra and morphologically abnormal megalopa stage was associated with exposure to the crude oil. This has not been reported before.

Effects of temperature on the median tolerance limit of pink salmon and shrimp exposed to toluene, naphthalene, and cook inlet crude oil

The effects of temperature on the TLm's of pink salmon (Oncorhynchus gorbuscha) fry and shrimp (Eualus spp. and Pandalus goniurus) exposed to toluene, naphthalene, and the water-soluble fraction (WSF) of Cook Inlet crude oil were measured. Static exposures were used in which the initial concentration of the toxicant declines with time, a situation that would also occur with an oil spill. Both the persistence of oil and the physiology of animals are affected by temperature, and the measured TLm's are the net result of both variables operating simultaneously. Toluene, a mononuclear, and naphthalene, a dinuclear aromatic hydrocarbon, were tested because they represent aromatic compounds implicated as major contributors to oil toxicity.

Mortality of Experimentally Descaled Smolts of Coho Salmon (Oncorhynchus kisutch) in Fresh and Salt Water

Removal of slime from 25% of the body caused no deaths among smolts of coho salmon in fresh water or in seawater (28‰). Removal of slime and scales from the same percentage of body area caused no deaths in fresh water, but 75% mortality within 10 days in seawater. The 10-day median tolerance limit was 10% scale removal immediately before the smolts entered seawater. Mortality was highest when the scales were removed from the area of the rib cage. Recovery of smolts in fresh water from a loss of scales that would be lethal in seawater occurred rapidly; 90% of the fish regained tolerance to seawater within 1 day.

AMMONIA IN TEXAS STREAMS DURING LOW FLOW FROM MUNICIPAL WASTEWATER1

ABSTRACT: An investigation of treated municipal wastewaters discharged into Texas streams was conducted to determine the probable effect of concentrations of ammonia in receiving waters, based on existing data on ammonia levels which are lethal to various species of fish. Recorded data for most Texas cities were analyzed. Based on existing toxicity criteria for ammonia of 1/10 TLm= 0.31 mg/1 NH3‐N, employing known discharge flow rates, and 7‐day, 5‐year or 7‐day, 10‐year low flows in Texas streams, appreciable numbers of sites were found to pose a threat to various species of fish. Using the bluegill (Lepomis macrochirus) as a median tolerance limit species, data from 65 cities which met the aforecited requirements, were analyzed. Those included a total of 92 wastewater effluents. Sixty‐nine percent of those cities and 70% of their effluents exceeded the 0.31 mg/1 NH3‐N limit in the stream below the discharge point. Thirty‐seven percent of the cities equaled or exceeded the 96‐hour TLm concentration limit of 3.1 mg/1 ammonia. Based on the 10 mg/1 NO3‐N standard for intake water for potable supplies, 32% of the effluents resulted in a stream concentration which exceeded 10 mg/1, assuming a straight conversion of NH3‐N to NO3‐N.

Experimental studies on the accumulation of copper and zinc in the green mussel

Toxicity of copper and zinc to the green mussel, Mytilus viridis was evaluated by short-term bioassays. Probit analysis was used for calculating 48 h median tolerance limits, 95% fiducial limits and slope functions ( S). The rates of copper and zinc accumulation were determined by analysing the metal content in the soft parts of the mussels at fixed intervals of time by atomic absorption spectrometry. Bioaccumulation was determined as a function of metal concentration in the experimental medium. The correlations for the regression lines ( P < 0.1%) indicate that the uptake of metal is linear at least for the first five weeks. During a more extended experimental period, adjustment to a steady state probably occurs.

Biocides in Relation to Water Pollution Part I: Bioassay Studies on the Effects of a few Biocides on Fresh Water Fish, Channa gachua

Abstract ‐ In the present paper the toxicity of four biocides, endrin, thiodon, malathion and phosvel, has been measured by performing static bioassay experiments with Channa gachua as test fish to establish the median Tolerance Limits (TLm and TL50). ‐ The results of bioassay experiments indicate that the fish is harmed even at a very low concentration of these biocides. The values of TLm are 0.0076, 0.0073, 0.00695 and 0.0068 for endrin; 0.01120, 0.01088, 0.01069 and 0.01064 for thiodon; 9.20, 8.10, 7.90 and 7.60 for malathion and 32.90, 32.10, 31.65 and 31.15 mg/l for phosvel for the time interval of 24, 48, 76 and 96 hours, respectively. ‐ As indicated by TLm's, endrin is most toxic and phosvel least. Thiodon and malathion came in a descending order between endrin and phosvel. ‐ During bioassay studies, the effect of some variables, like temerature, pH and fish‐size, on TLm's has also been observed. They gave the following results. a) An increase in temperature increased the toxicity of all the biocides. b) An increase in pH decreased the TLm as such, making the biocides more toxic to Channa gachua. c) For larger fishes, the biocide solutions were less toxic, but the same solutions were more toxic to fishes of a smaller size. ‐ The safe harmless concentrations of endrin, thiodon, malathion and phosvel are ‐ 0.00289 mg/l, 0.00337 mg/l, 1.88365 mg/l and 9.16736 mg/l, respectively.

Biochemical decomposition of coal-tar dyes. II. Acute toxicity of coal-tar dyes and their decomposed products.

Twenty kinds of coal-tar dyes were subjected to median tolerance limit (TLm) test by use of Himedaka (Oryzias latipes) for the comparision of their acute toxicities. It became clear that 4 kinds of halogens substituted xanthene compounds dyes showed strong acute toxicities. From the fact that uranine had the lower acute toxicity than halogens substituted compounds and the toxicities of these 4 dyes increased through irradiation, it was assumed that halogen atoms in dyes might be responsible for these strong acute toxicities to fish.

Copper tolerance and segregation distortion in aged Paramecium

The effect of age on copper tolerance and genetic phenomena in Paramecium has been investigated. Regression analysis of paired observations of log median tolerance limit to copper and age in fissions on four different days has shown that there is no reason to reject the null hypothesis that age has no effect on copper tolerance. Older cells are not, therefore, necessarily more susceptible to environmental stress as is often assumed. The isolation of starved cells from clones which are very old frequently results in inviability, but the progeny of 5 lines which had a high percentage of viability showed highly distorted segregation ratios at 4 marker loci. Eleven of the 19 ratios differed significantly from the expected 1 : 1. The distorted segregation was not consistently biased toward one allele nor were subclones of a single clone biased in the same direction. An interpretation is presented which suggests the distorted segregation is an artifact. It is proposed that segregation distortion results as a consequence of individual cells entering autogamy at different times rather than synchronously as they starve. If true this hypothesis has important technical implications for the measurement of viability at autogamy in aged lines.

Acute toxicity of inorganic chloramines to early life stages of brook trout (Salvelinus fontinalis)

The acute toxicity of inorganic chloramines to brook trout alevin, fry, and juvenile life stages was determined in 96‐h tests. Toxicity was not constant between the life stages. Alevins were more tolerant than the fry group tested. Alevins showed a decreased tolerance with an increase of body weight. Two groups of juveniles were similar in tolerance to the heaviest alevin group. A relationship between life stage‐body weight of brook trout and 96‐h median tolerance limits is presented.

Chlorine-Induced Mortality of Eggs and Larvae of Spotted Seatrout (Cynoscion nebulosus)

The acute lethal effects of sodium hypochlorite, chloramine, and 5-chlorouracil on eggs and larvae of spotted seatrout, Cynoscion nebulosus, are presented. Forty-eight-h median tolerance limits (TLm) for the various toxicants and age classes (2-h-old eggs, 10-h eggs, and 1-h posthatch larvae) were, respectively: sodium hypochlorite—0.21 ± 0.01, 0.21 ± 0.01, 0.17 ± 0.28 ppm; chloramine—14.14 ± 1.13, 0.57 ± 0.28, 5.75 ± 3.01 ppm; 5-chlorouracil-8.91 ± 1.03, > 100, 79.43 ± 44.97 ppm. The 48-h TLm varied depending on toxicant and age class.

Comparative Cold Resistance of Three Columbia River Organisms

Resistance to abrupt and gradual cold shock was determined in bioassays with pumpkinseed (Lepomis gibbosus), rainbow trout (Salmo gairdneri), and a northwestern crayfish (Pacifastacus leniusculus) acclimated to higher temperatures at 5 C increments. Test criteria were median tolerance limits (TLm) for 96-h exposures after abrupt cold shock, and 50% loss of equilibrium (LE50) for decline rates of 18, 15, 10, 5, and 1 C/h during gradual cold shock. Cold resistance depended on original acclimation temperature (AT) and varied among species under both test conditions in the order: pumpkinseed < rainbow trout < crayfish. The lower TLm limit for pumpkinseed was 12.3 C at 30 C AT, 9.6 C at 25 C AT, 4.5 C at 20 C AT, and 2.7 C at 15 C AT. Rainbow trout at 20, 15 and 10 C AT survived abrupt exposures to cold down to 3.3, 1.4 and 0.5 C, respectively. Crayfish at 25, 20 and 15 C AT survived exposures down to 2.5, 0.4 and 0.0 C, respectively. TLm values were slightly above LE50 values for both fish species but well below for crayfish. Partial adaptation significantly lowered LE values at decline rates below 18 C/h for pumpkinseed, and to a lesser extent for the other two species, thus extending the lower margin of cold resistance.

Copper toxicity in the pacific oysterCrassostrea gigas

A laboratory study was designed to determine the lethal concentration of Cu to the Pacific oyster. Oysters 18 to 24 months old and sexually mature were held in running unfiltered sea water (33 percent), pH8, at 12 to 15/sup 0/C for one week prior to testing. The oysters were exposed to Cu concentrations of 0.10, 0.25, 0.50, 0.75, and 1.00 ppM for three separate 96-hr experiments to determine the median tolerance limits (TL/sub m/), the concentration at which 50 percent of an experimental population are dead after 96 hours for this study. The 96-hr TL/sub m/ was estimated to be 0.56 ppM. This value is much higher than the concentrations from 0.001 to 0.010 ppM found in the natural environment. Because adult oysters were used in this study, concentrations lower than 0.56 ppM may be presumed to be lethal to the more susceptible egg and larval stages. Further studies using lower salinities and pH and higher temperatures may have elicited a lower TL/sub m/ value than 0.56 ppM.

Herbicide toxicities in some Australian anurans and the effect of subacute dosages on temperature tolerance

Tadpoles of the anurans, Adelotus brevis, Limnodynastes peroni, and Bufo marinus were exposed to a range of concentrations of up to ten different herbicides. The Median Tolerance Limit (TL50) was calculated for each toxicant from data obtained by static bioassay. Some adult frogs (Litoria ewingi and Limnodynastes tasmaniensis) were subjected to greater concentrations of several of the toxicants. Toxicity varied greatly among the tadpoles exposed to various toxicants with fenoprop being the most toxic chemical tested, while no differences were observed in behaviour or activity between the exposed and control adult frogs. A significant reduction occurred in the thermal tolerance of one to two week old A. brevis exposed to subacute dosages of amitrole-T, picloram, and 2,2-DPA.

Studies on the Offensive-Odor Fish of the Nagara River. VII. Median Tolerance Limit Test of the Offensive-Odor Substances

The three components, volatile fatty acids, aromatic hydrocarbons, and phenol, found as the main substances responsible for the unpleasant odor in fish meat, can also act as a toxic substance. In order to know the toxicity of these substances to fish and to reveal the correlation between water quality and toxicity in the area where fish with bad odor lived, median tolerance limit (TLm) tests were made with a carp (Cyprinus carpio L.). The values of TLm found for acetic acid were 69 ppm for 24 hr and 49 ppm for 48 hr, those for propionic acid were 96 ppm for 24 hr and 73 ppm for 48 hr, those for butyric acid were 85 ppm for 24 hr and 65 ppm for 48 hr, and those for valeric acid were 92 ppm for 24 hr and 72 ppm for 48 hr, and those for phenol were 3.6 ppm for 24 hr and 1.7 ppm for 48 hr. In aromatic hydrocarbons, the fish were alive even in 1500 ppm of any of them and TLm values could not be measured. In the TLm tests with a mixture of these substances, concentrations of these substances in the water area in which fish with unpleasant odor lived were several tenths to several hundredths of the experimental TLm values, since the fish can live in such waters. These substances are considered to act as an inducer and the fish living in such polluted waters for a long period of time acquire unpleasant odor.

Acute and chronic toxicity of copper to the fathead minnow in a surface water of variable quality

Acute and chronic toxicity tests conducted with the fathead minnow and copper used as the source of dilution water a natural stream to which a sewage treatment plant upstream contributed a variety of materials known to affect acute copper toxicity. Nominal total copper 96-h median tolerance limit values (96-h TL50), determined with static testing procedures, ranged from 1.6 to 21 mg l−1. Dissolved copper 96-h TL50 values ranged from 0.60 to 0.98 mg l−1. The maximum acceptable toxicant concentration (MATC) based on survival, growth, reproduction, and hatchability of eggs was between 0.066 and 0.118 mg l−1.

Acute Toxicity of Methyl Mercury Chloride and Mercuric Chloride for Rainbow Trout (Salmo gairdneri) Fry and Fingerlings

The median tolerance limit (MTL) for methyl mercury chloride at 24, 48, and 96 h was 0.084, 0.045, and 0.024 mg/liter as mercury, respectively, for fry; and 0.125, 0.066, and 0.042 mg/liter as mercury, respectively, for fingerlings. The MTL (24 h) for mercuric chloride for fingerlings was 0.90 mg/liter as mercury. Fingerlings exposed to methyl mercury chloride concentrated mercury in their tissues much more rapidly than did those exposed to mercuric chloride. The acute toxic action of both compounds was exerted on the gills. Mercuric chloride caused severe epithelial necrosis. Poisoning by methyl mercuric chloride was characterized by epithelial cell swelling and hyperplasia, a marked increase in the number of epithelial cells in mitosis, and terminal epithelial desquamation.

Effects of mercury on survival and development of the larval grass shrimp Palaemonetes vulgaris

Effects of 7 concentrations of mercury from 0.0 (control) to 0.056 ppm on survival and development of the larval grass shrimp Palaemonetes vulgaris (Say) were investigated. A concentration of 0.056 ppm Hg was toxic to all larvae within 24 h, but below a threshold level (≤0.0056 ppm) no lethal effect occurred within 48 h. Feeding appeared to increase slightly the resistance of P. vulgaris larvae to mercury, and 48-h TLm's (median tolerance limits) for fed and unfed larvae were 0.0156 and 0.0100 ppm, respectively. Delayed effects of 48-h exposure to sublethal mercury concentrations which appeared in later post-exposure rearing of the larvae included (1) reduced survival to the postlarval stage, (2) delayed molting, (3) extended development time, (4) increased numbers of larval instars, and (5) morphological deforment

Genetic analysis of copper resistance in Paramecium aurelia syngen 4.

Measurement of the median tolerance limit to cupric ion of 28 wild stocks of Paramecium aurelia syngen 4 revealed a phenotypic polymorphism: two stocks showed a much greater resistance than the others. Genetic analysis showed the resistant phenotype was produced by a recessive allele, cur, identical in both resistant wild stocks. No modification of the phenotypic expression of this allele could be detected after backcrossing into different genetic backgrounds. The results are interpreted to support the importance of mutational adaptation in this inbreeding species. Possible patterns of internal genetic organization of species which rely on mutation for adaptation are discussed.

Acute cadmium toxicity studies upon nine species of aquatic insects

Continuous-flow bioassays were employed to determine 96-hour median tolerance limits (TLm), for the stonefly, Pteronarcella badia (Hagen) (TLm was 18.0 mg Cd/l) and the mayfly, Ephemerella grandis grandis Eaton (TLm was 28.0 mg Cd/l). Ninety-six hours TLm values for other species of aquatic insects tested were not determined, since these species were relatively insensitive to cadmium. Insects exposed for four days in cadmium-containing water, then placed in tap water, show a linear rate of cadmium loss. This loss may lower or prevent mortality under ideal conditions.

THE EFFECT OF PRUDHOE BAY CRUDE OIL ON SURVIVAL AND GROWTH OF EGGS, ALEVINS, AND FRY OF PINK SALMON, ONCORHYNCHUS GORBUSCHA

ABSTRACT Standard 96-hour bioassays with “total” oil solutions in fresh water and seawater determined differences in sensitivity of the developing life stages of pink salmon (Oncorhynchus gorbuscha). Eggs were the most resistant and emergent fry (yolk sac absorbed) the most sensitive to acute 4-day exposures. In fresh water, the 96-hour median tolerance limit (TLm) of fry was 0.4 ml oil/liter mixed mechanically (12 ppm as measured in subsurface water by infrared spectrophotometry). In seawater, it was 0.04 ml oil/liter mixed mechanically (6 ppm as measured in subsurface water by infrared spectrophotometry). Three life stages of alevins were exposed to 10-day sublethal exposures of the water-soluble fraction to determine what doses might affect growth. Growth was affected most severely in alevins exposed during later developmental stages. Decreased growth was observed in fry after 10-day exposures at the lowest dose tested–0.015 ml oil/liter mixed by water agitation (0.73 ppm in subsurface water by infrared spectrophotometry–less than 10% of the 96-hour TLm limit for that life stage). In fresh water, susceptibility of early life history stages of pink salmon to oil pollution is great at the time of emergence (completion of yolk absorption). Susceptibility is even greater in seawater after fry migration.