Acute toxicity of oil dispersants to marine fish larvae

The acute toxicities of several oil dispersants to the larvae of haddock, herring, lemon sole, pilchard, plaice and sole were examined, the type and aromatic content of the solvent being the main factors influencing the toxicity. Newer (second generation) dispersants had much lower toxicities. Ageing of dispersant solutions led to a decrease in toxicity, which could be related to loss of aromatic compounds from solution. Temperature and salinity had only slight influence on toxicity. For all dispersants, differences of susceptibility between species were less than differences at different ages within a species. The larvae of all species showed a similar susceptibility when newly hatched, and susceptibility increased throughout the yolk-sac stage. The transition period from yolk reserves to an external food supply was most critical, for once larvae had established feeding, resistance increased until metamorphosis. The dispersants appeared to act largely as physical toxins causing, initially at least, a reversible narcosis. The implications of the results are discussed in relation to the use of dispersants at sea.     

Development and functions of the shell sculpture of the marine snail Ceratostoma foliatum

The shell of the adult Ceratostoma foliatum (Gmelin) is characterized by three varices with foliations, and a tooth on the anterior portion of the outer lip. These features are derived gradually from the markedly different sculpture of shells of small juveniles (a network of fine axial and spiral cords). The sculpture changes as the thin, cord-like basic varix is elaborated, reinforced, and modified by the development of a secondary structure (the tooth) and as the number of varices per whorl decreases. Most muricid shell patterns can be derived from juvenile patterns similar to that of C. foliatum by quantitative variations in these four processes. Likely functions of the complex and varied muricid shell structures include stabilization in shifting substrates, defense against predators, and strengthening of the shell. Different functions and shell-growth patterns are likely for the different types of varices. Shell structures are most elaborate on shells of adults. A structure's functions are likely to change as the structure becomes more complex on each successive whorl. The functional period in an individual's lifespan is consequently restricted by the pattern of growth, the rate of structural development, and the rate of shell erosion.     

Induction and reversion of multixenobiotic resistance in the marine snail Monodonta turbinata

Many marine organisms inherently express the presence and function of a new defence mechanism, termed multixenobiotic resistance mechanism (MXRM) because of its similarity to multidrug resistance (MDR) found in tumor cell lines resistant to chemotherapeutic drugs. However, previously no information was available on a possible induction of the activity of MXRM in organisms living at polluted sites. The purpose of the present study was to demonstrate the inducibility of this defence mechanism in the marine snail Monodonta turbinata, an organism known to inhabit a wide range of environmental conditions existing along a pollution gradient. Specimens of M. turbinata used in the present study were collected from March 1993 through March 1994 near Rovinj, Croatia. The accumulation of generally labelled ³H-vincristine (³H-VCR) in the gills of snails living at an unpolluted site was 67% higher and very sensitive to verapamil, an inhibitor of P-glycoprotein activity in comparison to snails living at a polluted site. The accumulation of vincristine (VCR) in snails from a polluted site was reduced and insensitive to verapamil due to the induced state of P-glycoprotein, as was demonstrated immunochemically by the enhanced concentration of a 140 kDa protein cross-reacting with the polyclonal antibodies raised against mammalian P-glycoprotein. MXRM could be induced in snails from the unpolluted site to the level found in snails living at a polluted site either by transplantation for 3 d to a polluted site, or by exposure for 3 d to sea water polluted with Diesel-2 oil (hydrocarbon concentration equivalent to 50 ppb of Kuwait oil). Discovery of the inducibility of this new defence mechanism in aquatic organisms may have important implications in ecotoxicology, as was demonstrated by a 104% enhanced accumulation of VCR in the presence of the MXRM-inhibitor, the so-called chemosensitizer. Besides, a striking difference in the levels of MXRM-elements (the sensitivity of the accumulation rate of xenobiotics to verapamil, immunochemical expression of P-glycoprotein, and the sensitivity of the binding of xenobiotics on membrane vesicles to verapamil) found between specimens living at the polluted and unpolluted sites offers a new molecular biomarker for exposure to pollutants.     

Ecology of toxicity in marine sponges

An investigation of the ecology of toxicity in marine sponges from different latitudes on the North American continent was made. Results indicated that toxicity in sponges increased with decreasing latitude. Three of the 34 species (9%) of sponges from San Juan Island, Washington, USA (48°N), were toxic to fishes. Nine of the 44 species (20%) of sponges from Santa Catalina Island, California, USA (33°N), were toxic. Seven of the 11 species (64%) of sponges from Zihuatanejo Bay, Guerrero, México (17°N), were toxic. Twenty-seven of the 36 species (75%) of sponges from La Blanquilla, Veracruz, México (19°N), were toxic. Most of these toxic sponges are openly exposed to fishes. The most common exposed sponges proved to be highly toxic to fishes. Force-feeding experiments conducted with wrasses demonstrated the effectiveness of the toxin of sponges. A hypothesis is proposed which explains the relationship between species diversity of fishes and sponge toxicity with latitude.     

Occurrence of tri-n-butyltin-caused imposex in the North Pacific marine snail Nucella lima in Auke Bay,Alaska

Like female dog whelks (Nucella lapillus) in the Atlantic Ocean, females of the Pacific gastropod N. lima respond to low concentrations of tri-n-butyltin (TBT) by growing a penis and vas deferens. This condition, termed imposex, was found to occur in N. lima collected from August 1987 to May 1988 along a TBT pollution gradient associated with a marina in Auke Bay, Alaska. The suite of symptoms characteristic of imposex in N. lima was slightly different than in N. lapillus. Imposex, as measured by relative penis size (RPS) of females to males, increased from 0.0 to 34.27 along this gradient and as measured by vas deferens sequenceindex (VDS) increased similarly from 0.0 to 4.29. Concentrations of TBT in N. lima increased from below detection limits (about 0.010 g Sn g^-1 dry tissue wt) to 0.065 g Sn g^-1 dry tissue wt along the gradient. The gradient was determined by measuring TBT in whole-body tissues of bay mussels (Mytilus edulis). Concentrations of TBT in mussels increased from below detection limits to 0.833 g Sn g^-1 dry tissue wt in mussels from within the marina that was the major local source of TBT. Imposex, tissue TBT burden, and position along a TBT pollution gradient are significantly correlated (P<0.01) in N. lima. TBT was tested as a causative agent for imposex by exposing snails at a distant control site to TBT paint. After 1 mo exposure, 33% of the females grew a penis ranging in size from 0.2 to 0.8 mm. Our results generally corroborate those found for N. lapillus and indicate that imposex in N. lima is caused by environmental TBT exposure. We suggest that the RPS in the genus Nucella may be useful in monitoring TBT in coastal waters worldwide.     

Bioenergetics and survival of the marine snail Thais lima during long-term oil exposure

The carnivorous snail Thais lima was fed Mytilus edulis during a 28-d exposure to the water soluble fraction (WSF) of Cook Inlet crude oil. The LC-50 of T. lima declined from >3000 ppb aromatic hydrocarbons on Day 7 to 818±118 ppb on Day 28. The LC-50 of M. edulis declined from >3 000 ppb aromatic hydrocarbons on Day 7 to 1 686±42 ppb on Day 28. Predation rate declined linearly with increasing aromatic hydrocarbon concentration up to 302 ppb; little predation occurred at 538 ppb and none at 1 160 or 1 761 ppb. Snail absorption efficiency averaged 93.5% and did not vary as a function of WSF dose. Total energy expenditure (R+U) increased at 44 ppb aromatics and declined at lethal WSF exposures. At sublethal WSF exposures, percentages of total energy expenditure were: respiration (87%), ammonia excretion (9%) and primary amine loss (4%). These percentages did not vary as a function of WSF dose or time. Oxygen:nitrogen ratios were not affected by WSF concentration or time and indicated that T. lima derived most of its energy from protein catabolism. The uptake of aromatic hydrocarbons into the soft tissues of snails and mussels was directly related to the WSF concentration. Naphthalenes accounted for 67 to 78% of the aromatic hydrocarbons in T. lima and 56 to 71% in M. edulis. The scope for growth was negative above 150 ppb WSF aromatic hydrocarbons and above 1 204 ppb soft-body aromatic hydrocarbons. These snails were physiologically stressed at an aromatic hydrocarbon concentration which was 19% of the 28-d WSF LC-50 (818±118 ppb) and/or 48% of the 28-d LC-50 of soft tissue aromatics (2 502 ppb).     

Controls of spatial variation in the prevalence of trematode parasites infecting a marine snail

Geographic variability in abundance can be driven by multiple physical and biological factors operating at multiple scales. To understand the determinants of larval trematode prevalence within populations of the marine snail host Littorina littorea, we quantified many physical and biological variables at 28 New England intertidal sites. A hierarchical, mixed-effects model identified the abundance of gulls (the final hosts and dispersive agents of infective trematode stages) and snail size (a proxy for time of exposure) as the primary factors associated with trematode prevalence. The predominant influence of these variables coupled with routinely low infection rates (21 of the 28 populations exhibited prevalence <12%) suggest broad-scale recruitment limitation of trematodes. Although infection rates were spatially variable, formal analyses detected no regional spatial gradients in either trematode prevalence or independent environmental variables. Trematode prevalence appears to be predominantly determined by local site characteristics favoring high gull abundance.     

Mechanism of toxicity of zinc to the marine diatomNitzschia closterium

The effect of zinc on cell division, photosynthesis, ultrastructure, respiration, ATP levels, mitochondrial electron-transport chain (ETC)-activity, total thiols and glutathione in the marine diatomNitzschia closterium (Ehrenberg) W. Smith was investigated. Although 65µg Zn 1^–1 halved the cell division rate, photosynthesis and respiration were unaffected by zinc concentrations up to 500µg Zn 1^–1. Most of the zinc associated with the cells was bound at the cell surface, with only 3 to 4% of this extracellular zinc penetrating the cell membrane. Once inside the cell, zinc exerted its toxicity at a number of sites. Increased ATP production and ETC activity were observed in zinc-treated cells. Zinc also enhanced cellular thiols (SH) and total glutathione, and zinc toxicity was reversible by the addition of thiol compounds such as cysteine. Zinc-thiol binding may be a detoxification mechanism for the cell. It is suggested that increased ATP production may provide the energy required for increased glutathione synthesis at the expense of other energy-requiring processes including cell division. The mechanisms of toxicity of ionic zinc and copper toN. closterium were compared.     

Factors influencing food choice by the seaweed-eating marine snail Norrisianorrisi (Trochidae)

Through two-choice gustatory experiments, a␣preference hierarchy was established␣for␣the␣herbivorous gastropod Norrisianorrisi Sowerby, with laminarialean kelps preferred over all other seaweeds. Among the kelps, laminae of Macrocystispyrifera were slightly preferred over Egregiamenziesii, and both were strongly preferred over sporophylls of Eiseniaarborea. E.arborea, the least preferred kelp, was consistently chosen over other algae common in the snail's habitat (Halidrysdioica, Dictyotaflabellata, and Pterocladiacapillacea) and over seaweeds believed to be edible and palatable based on their morphology, structure, and secondary chemistry (Endarachnebinghamiae, Mazzaellaflaccida, and Ulvalobata). The morphologies and structural toughness of tested seaweeds varied significantly as did their nutritional (% carbon, % nitrogen, C:N ratio, and % ash) contents and phlorotannin concentrations; however, snails preferred to feed on kelps regardless of nutritional content, toughness or phlorotannin concentration; and among kelps preferred to feed on the least tough species (based on penetrometer measurements), which also were those containing the lowest phlorotannin concentrations. Preference for kelp was not upheld in experiments using agarose thalli to which freeze-dried powder, of either the kelp Eiseniaarborea or non-kelp Endarachnebinghamiae was added, suggesting the destruction of attractant chemicals during the making of the artificial foods. Our data suggest that the preference of N. norrisi for kelps over other potentially edible and palatable seaweeds may not be related to nutritional content, but instead may have evolved in response to factors such as availability, habitat provision, or refuge from predation. Received: 27 September 1996 / Accepted: 7 October 1997     

Acute toxicity of ammonia to a freshwater teleost,Labeo bata larvae

Ammonia toxicity tests were performed with Labeo bata (bata) larvae of three different size groups. One hundred percent survival of larvae (500.0?±?4.0?mg) was recorded when exposed to ammonia concentrations of 1.0–13.56?mg?L^?1 at 96?h of exposure. Bata larvae exposed to ammonia concentrations of 15.8–25?mg?L^?1 showed 10–74% mortalities. The 96?h LC₅₀ value for 200 (±5), 250 (±2) and 500 (±4) mg bata larvae were 11.5, 16.8 and 22.5?mg?L^?1 un-ionised ammonia concentrations, respectively. When fish were exposed to different doses of ammonia, behavioural changes immediately occurred even at the lowest dose. At first, the fish became hyperexcitable, the skin darkened and they showed an increased ventilation frequency, fish behaviour became normal, 24?h after exposure. A 96?h LC₅₀ value of un-ionised ammonia showed direct relationship with the increasing size of bata larvae.     

Inhibitory effect of arachidonic acid on venom acetylcholinesterase

The venom of krait (Bungarus sindanus), an Elapidae snake, contains high level of acetylcholinesterase (AChE) activity. The effect of arachidonic acid on krait (Bungarus sindanus) venom AChE (acetylcholine hydrolase, EC 3.1.1.7) was studied using kinetic methods. This study evaluated for the first time whether arachidonic acid acts as potential AChE inhibitor of krait venom. Kinetic studies, using Line-Weaver Burk and Dixon plots, indicated that the inhibition produced by arachidonic acid was non-competitive, i.e., both k_m and V _max fell with increase in the concentration of arachidonic acid. The concentration of arachidonic acid required to inhibit 50% of enzymatic activity was found to be 1.9?µM while the inhibitory constant (K_i ) was 1.4?µM. The present results suggest that essential fatty acid (arachidonic acid) may also be used as an inhibitor of snake venom AChE.     

苯、氯苯、苯酚、4-氯酚对斑马鱼、孔雀鱼、剑尾鱼的急性毒性

以斑马鱼（Zebra fish）Danio rerio、剑尾鱼Xiphophorus hellerii、孔雀鱼（Guppy）Poecilia reticulata为受试鱼种,采用半静态试验,考察苯、苯酚、氯苯、4-氯苯酚对3种鱼的急性毒性,结果表明,上述4种有机物对斑马鱼的96 h LC50分别为132.22、28.86、9.66、4.29 mg.L-1;对剑尾鱼的96 h LC50分别为123.76、27.25、8.86、4.29 mg.L-1;对孔雀鱼的96 h LC50分别为131.25、27.88、9.33、4.59 mg.L-1,都属于高毒物质。毒性大小为苯〈苯酚〈氯苯〈4-氯苯酚。毒性大小与取代基的类型有关,-Cl的毒性要大于-OH,-Cl和-OH的联合毒性大于单独的-Cl和-OH。孔雀鱼和剑尾鱼对上述有机污染物具有较好的敏感性,结果稳定,重现性好,可以作为急性毒性试验的受试鱼种。     

Metallothioneins and lysosomes in metal toxicity and accumulation in marine mussels: the effect of cadmium in the presence and absence of phenanthrene

It has been confirmed that metallothioneins play an important role in the accumulation of cadmium (Cd) in the digestive gland cells of mussels (Mytilus galloprovincialis Lam.). The content of Cd in the tissue of mussels exposed for 9 d to the metal (estimated dosage of 180 g Cd mussel^-1 d^-1) was 66.2 ppm. This value is about the same as the metal content found in the digestive gland of Cd-exposed mussels kept in clean water for a recovery period of 28 d. At the end of the recovery period, however, the Cd bound to thionein had increased by approximately 250%. Our data demonstrate that the stability of lysosomes, a biological parameter adopted as a cellular stress index, is extremely low in mussels exposed to Cd for 9 d, but returns to control values in the digestive gland cells of mussels allowed to recover for 28 d in uncontaminated sea water. At this point most of the Cd present in the cytosol is bound to thionein. These data demonstrate the importance of metallothionein induction in the reduction of the cytotoxic effects exerted by high levels of Cd accumulation. The results of tests designed to clarify the reasons for the long biological half-life of Cd demonstrated that, in the digestive gland of mussels, the lysosomes are not able to eliminate Cd either bound to insoluble thionein polymers or to lipid peroxidation products such as lysosomal lipofuscin, both of which are apparently involved in the elimination of copper. The absence of these two mechanisms of metal sequestration and elimination via excretion of residual bodies (tertiary lysosomes) is in agreement with the persistence of cadmium in the digestive gland of mussels. Finally, the results also demonstrate that simultaneous exposure of mussels to Cd and phenanthrene, an established lysosomal membrane destabilizer, did not significantly alter the accumulation of Cd or the kinetics of the metal in mussels.     

Acute toxicity of 30 pharmaceutically active compounds to freshwater planarians,Dugesia japonica

Pharmaceutically active compounds are produced worldwide and consumed in large quantities, so these chemicals are frequently detected in limnic environments posing potential ecological risks. Thirty pharmaceutically active compounds were selected for examination of their acute toxicity for freshwater planarians (Dugesia japonica). Among the 30 compounds tested, diclofenac, mefenamic acid, naproxen, propranolol HCl, and diphenhydramine HCl had a 48-h nominal LC₅₀ below10 mg L^?1, and for 18 chemicals, it exceeded 100 mg L^?1. The 96-h nominal LC₅₀ was below 10 mg L^?1 for diclofenac, mefenamic acid, naproxen, propranolol HCl, diltiazem HCl, diphenhydramine HCl, hydroxyzine HCl, and triprolidine HCl, and for 15 chemicals, it exceeded 100 mg L^?1. Among different therapeutic groups, analgesics were most toxic to planarians, and antibiotics were least toxic. Antihistamines and beta blockers varied in their acute toxicity to planarians. At the current environmental levels, none of the tested pharmaceutically active compounds may have acutely harmful impacts on aquatic invertebrates. To answer the question whether chronic, long-term exposure to pharmaceutically active compounds may entail ecological risks for aquatic ecosystems, further investigations with different end points in multiple species tests are needed.     

Assessing the toxicity of chemical compounds associated with marine land-based fish farms: The use of mini-scale microalgal toxicity tests

Many chemicals that are currently used in aquaculture have not been evaluated with regard to their specific effects on the aquatic environment. In the present study, the toxic effects of several chemicals associated with land-based marine fish farming activities were assessed using two species of marine microalgae (Phaeodactylum tricornutum and Isochrysis galbana). Mini-scale toxicity tests were performed with six antibiotics (amoxicillin, ampicillin, flumequine, oxytetracycline, streptomycin and sulfadiazine) and two disinfectants (formaldehyde and hypochlorite). Amoxicillin and streptomycin did not exert toxic effects. Sulfadiazine was the most toxic chemical; the EC₅₀ values were 0.11 mg/L and 1.44 mg/L for P. tricornutum and I. galbana respectively. As expected, the disinfectants displayed high toxicity, and P. tricornutum was particularly sensitive to these compounds. Although the differences in microalgal sensitivity depended on the chemical considered, both species were highly sensitive to most of the compounds tested. We recommend the inclusion of mini-scale microalgal toxicity tests in environmental risk assessment (ERA) and environmental monitoring plans because they are cost-effective and rapid.     

Acute toxicity of industrial endocrine-disrupting chemicals,natural and synthetic sex hormones to the freshwater planarian,Dugesia japonica

Many chemicals commonly occurring in surface water are found to be hormonally active. Fourteen compounds including four sex hormones, three synthetic hormones, one non-steroidal anti-androgen, and six industrial endocrine-disrupting chemicals were selected to examine their acute toxicities on the freshwater planarian, Dugesia japonica. Among all test chemicals, diethylstilbestrol had the highest toxicity. Relatively, the toxicities of the synthetic hormones were higher than the natural ones. Among the six industrial endocrine-disrupting chemicals tested, bisphenol A was the most toxic, with a 48-h LC₅₀ of 8.3 mg L^?1. Overall, the natural or synthetic hormones, other than estrone and estriol, were more acutely toxic to planarians than the industrial endocrine disruptors tested. The acute toxicities of the test chemicals to Dugesia japonica were in the same order of magnitude as those to Daphnia magna based on available published data. Despite this study used non-environmentally relevant levels, such kinds of chemicals do not exist singly in the aquatic environment, but typically act in synergistic and/or additive ways in the complex environmental mixtures, and the total estrogen equivalents are much higher than a single chemical. This study stands as a starting point for other acute and chronic assays, namely using mixtures.     

溶藻菌发酵液及其溶藻产物的生物急性毒性试验

应用发光细菌（Photobacteriumphosphoreum）急性毒性试验,研究了溶藻菌（Streptomycessp．HJC-D1）发酵液及其对铜绿微囊藻（Microcystisaemgmosa）抑制产物的生物急性毒性。结果表明,溶藻菌发酵液本身对发光细菌具有一定的低毒性,发酵3-5d时其相对发光度为（67．59％1：3．11％）-（72．35％±2．76％）;体积分数5％的溶藻菌发酵液可有效抑制初始质量浓度高达（O．1483±0．0032）mg-L-1的铜绿微囊藻生长,其抑藻率达85％以上,且藻液毒性明显低于对照组;以微囊藻毒素为主要溶藻产物进行毒性试验发现,其半抑制质量浓度为1096．92μg·L-1,水体藻毒素质量浓度低于20μg·L-1时其生物毒性较低。     

Acute toxicity of copper sulphate to fresh water prawns

Fresh water prawns, Macrobrachium lamarrei and Macrobrachium dayanum (Crustacea-Decapoda) were subjected to static bioassay tests to ascertain the LC50 values of copper sulphate. The 24, 48, 72 and 96 hr LC50 values of copper sulphate for M. lamarrei were 0.38, 0.361, 0.343 and 0.300 mg/l and for M. dayanum were 1.634, 0.988, 0.532 and 0.418 mg/l respectively. Behavioral responses and LC50 values indicate that M. lamarrei were more sensitive to copper sulphate than M. dayanum.     

Acute hematological toxicity of ivermectin to juvenile Clarias gariepinus

Abstract

Acute behavioral and hematological toxicity of ivermectin to C. gariepinus juveniles were assessed under static conditions at concentrations of 9 to 25?µg L^?1 for up to 4?days. Juveniles were highly sensitive to ivermectin, with an LC50 of 15?µg L^?1, culminating in spasms and paralysis. The hematological responses of packed cell volume, hemoglobin and red blood cell count decreased when compared to the control while the white blood cell count showed a biphasic trend. The mean corpuscular volume and mean corpuscular hemoglobin showed a mixed trend, while mean corpuscular hemoglobin concentration increased with increase in the concentration of the drug. Lymphocytes and neutrophils were also significantly (p?<?.05) increased. Ivermectin did not elicit any significant changes in monocytes, basophils and eosinophils. The observed changes confirm that ivermectin negatively affected the health of the fish. Therefore, real-time monitoring for early warning is recommended.