Accumulation and effects of organotin compounds in oysters and mussels: Correlation with serum biochemical and cytological factors and tissue burdens

Oysters and mussels exposed to a concentration of 0·7 ppb (μg/liter) tributyltin from painted panels in flowing seawater accumulated tin in the digestive glands to comparable levels. The mussels experienced approximately 50% mortality during the 60-day test period, but the oysters suffered virtually no deaths. There was no evidence from either bivalve of elevated numbers of hemocytes during the test period and no evidence for cellular disruption as detected by increased levels of serum lysosomal hydrolases. Serum protein of exposed mussels relative to controls increased with time of exposure to the toxicant, while oyster serum protein, normally 10 x higher than in mussels, did not. No evidence was found for elevated stress proteins (heat shock proteins) or metallothioneins in the serum hemocytes of either bivalve. Responses by these animals to fatal or near fatal doses of TBT were thus very different from responses to copper that we have reported elsewhere.^1,2     

Acute and chronic toxicity of the rice herbicides thiobencarb and molinate to opossum shrimp (Neomysis mercedis)

Neomysis mercedis were exposed to the rice herbicides molinate and thiobencarb, which have been detected in the Sacramento-San Joaquin Delta. Continuous-flow acute and chronic toxicity studies were performed. For thiobencarb, the 4-, 7- and 14-day LC_sos were 304, 214 and 91 μg/liter, respectively. For molinate, these values were 9910, 2530, and 820 μg/liter, respectively. Mortality stabilized after 18 and 28 days exposure, respectively, for thiobencarb and molinate. The incipient lethal concentrations were 53 and 230 μg/liter, respectively. Joint toxicity studies indicated additive toxicity for the two chemicals. Chronic no observable effects concentrations (NOECs) were estimated at 3·2 and 25·6 μg/liter for thiobencarb and molinate, with measurable effects occurring at 6·2 and 45·2 μg/liter, respectively. Environmental monitoring data suggests that concentrations of these chemicals in the Delta prior to 1985 may have exceeded the threshold for chronic toxicity, under conditions of joint exposure. However, due to continued improvements in pesticide management practices, environmental concentrations decreased to approximately 30 percent of the chronic threshold for joint toxicity by 1988. Baseline data on growth and reproduction relevant to toxicity tests are also presented for this species.     

Recovery of Mytilus edulis L. from chronic oil exposure

Previous laboratory studies¹ have shown that physiological and cellular processes of Mytilus edulis are affected by exposure to low and environmentally realistic concentrations of oil. However, there is little information concerning the rate of recovery from oil exposure and the extent to which physiological recovery may be related to the depuration of hydrocarbons from the tissues. The present study has shown a marked reduction in the feeding rate and scope for growth of mussels exposed to two concentrations of diesel oil (30 and 130 μg/litre) for 8 months. During recovery from oil exposure the depuration of hydrocarbons from the tissues was concomitant with the recovery of physiological performance. Mussels exposed to high oil concentrations (‘high-oil’ mussels) were found to recover more rapidly than those exposed to low oil concentrations (‘low-oil’ mussels), both in terms of depuration and scope for growth, and there was evidence of ‘catch-up’ growth. Recovery of both low- and high-oil mussels was complete after approximately 55 days.     

Response of hematological and biochemical parameters to heavy metal exposure: Implications in environmental monitoring

The use of selected hematological and biochemical parameters as indicators of metal exposure in aquatic organisms was evaluated. The hematological and biochemical parameters examined include glucose, hematocrit and aminotransferase levels in golden shiners exposed to cadmium. Cadmium exposure produced significant alterations in the levels of glucose, aspartate aminotransferase and alanine aminotransferase; however, hematocrit was not altered by exposure to cadmium. In addition, the comparative activity of Na/K adenosine triphosphatase (ATPase) was evaluated in the fathead minnow, golden shiner and bluegill sunfish. Basal Na/K ATPase activity was lowest in golden shiner (1·01 μmol Pi/mg protein/h) and highest in bluegill sunfish (1·45 μmol Pi/mg protein/h). While a stimulation of Na/K ATPase activity was observed at an exposure concentration of 1 μg Cd/liter in the fathead minnow and bluegill sunfish, inhibition of enzymatic activity was observed at higher exposure concentrations (10 and 100 μg Cd/liter). Gill Na/K ATPase activity in golden shiner was not significantly influenced by cadmium exposure. The observed insensitivity of ATPase in shiner may, in part, be related to higher background and accumulated concentrations of cadmium in gill tissue.     

The relationship between the copper complexing capacity of sea water and copper toxicity in shrimp zoeae

Mortality of larval coon-stripe shrimp, Pandalus danae, was related to labile copper and the copper complexing capacity of sea water, as measured by differential pulse Anodic Stripping Voltammetry (ASV). In nominal treatments of control, 5 and 10μg/litre Cu which contained less than 1·0μg/litre ASV labile Cu, zoeal development was usually complete. In treatments of 20 and 50μg/litre Cu which contained more than 7·0μg/litre ASV labile Cu, most larvae died while in the first zoeal stage. ASV labile Cu was related to the copper complexing capacity of sea water. Copper toxicity at less than 1·0 μg/litre ASV labile Cu is indicated by moulting delay and apparent Cu accumulation in zoea of the 5 and 10μg/litre Cu nominal treatments.     

Genotoxicity of copper oxide and silver nanoparticles in the mussel Mytilus galloprovincialis

Though there is some information on cytotoxicity of copper nanoparticles and silver nanoparticles on human cell lines, there is no information on their genotoxic and cytotoxic behaviour in bivalve molluscs. The aim of this study was to investigate the genotoxic impact of copper oxide and silver nanoparticles using mussels Mytilus galloprovincialis. Mussels were exposed to 10 μg L⁻¹ of CuO nanoparticles and Cu²⁺ and Ag nanoparticles and Ag⁺ for 15 days to assess genotoxic effects in hemocytes using the comet assay. The results obtained indicated that copper and silver forms (nanoparticles and ionic) induced DNA damage in hemolymph cells and a time-response effect was evident when compared to unexposed mussels. Ionic forms presented higher genotoxicity than nanoparticles, suggesting different mechanisms of action that may be mediated through oxidative stress. DNA strand breaks proved to be a useful biomarker of exposure to genotoxic effects of CuO and Ag nanoparticles in marine molluscs.     

Assessing site-specific effects of TBT contamination with mussel growth rates

During nine field transplant tests in San Diego Bay (1987–1990), juvenile mussels were exposed to mean concentrations of tributyltin (TBT) in ambient seawater ranging from 2 to 530 ng liter⁻¹ for 12 weeks under natural conditions. A total of 79 cages with 18 mussels each were monitored at 18 different sites. Growth and seawater TBT concentrations were measured weekly or on alternate weeks (biweekly). Mean growth rates ranged from 17 to 505 mg week⁻¹ (0·2 to 2·5 mm week⁻¹). Accumulation of TBT in mussel tissues was measured at the end of each 12-week test exposure and ranged from 0·1 to 3·2 μg g⁻¹ TBT wet weight. The frequency of the measurements and the integration of chemical and biological measurements improved the accuracy of the assessment over more traditional approaches. Growth was significantly related to seawater and tissue TBT. The statistical relationships with growth effects were used to estimate chemical effect zones for TBT in San Diego Bay. Site-specific differences were distinguished by additional statistical analyses and consideration of environmental significance.     

Gonadal development in Japanese medaka (Oryzias latipes) exposed to 17 β-estradiol

The purpose of this research was to evaluate the Japanese medaka (Oryzias latipes) as an ecotoxicological model for the rapid evaluation of environmental estrogens. A novel short-term (48-h) exposure to 17 β-estradiol is proposed in development of a positive control for disruption of gonadal development. Recently hatched medaka fry (30 fry per dose group) with undifferentiated gonads were exposed to 4.0, 29.4, and 115.6 μg/liter of 17 β-estradiol (acetone carrier) for 48 h in a water bath at 25 °C. The fry were then grown-out in spring water for 2 weeks, killed, and processed for histological evaluation. High lethality was encountered during the grow-out period in the 115.6 μg/liter dose group. Fry in the spring water and acetone (carrier) control groups developed into females or males. Fry exposed to 17 β-estradiol developed primarily into females or had testis-ova.     

Effects of toxicants on developing oocytes and embryos of the blue crab, Callinectes sapidus

Oocytes (90 μm in diameter) were isolated from ovaries of 14-day post-molt adult female crabs and maintained in culture media. The addition of cadmium (20 μg/ liter) or tributyltin (2 μg/liter) to developing oocytes resulted in decreases in the growth of oocytes as measured by protein and lipovitellin accumulation relative to controls. Crab embryos isolated from yellow ‘sponge’ of female blue crabs were maintained in seawater until hatching (6–8 days). Toxicants tested included cadmium, copper, tributyltin and endosulfan. Some of the processes or events which were followed included water uptake, lipovitellin utilization rate, formation of appendages, formation of a heart, formation of eyespots and hatching to zoea stage. The primary effects from addition of toxicants were deformed eyespots and reduced hatching success. The hatching EC₅₀ (concentration at which 50% of embryos failed to hatch) for copper, cadmium, tributyltin and endosulfan were 3.1, 0.25, 0.047 and 450 μg/liter, respectively. Crab embryos appear to be suitable for testing of the effects of a variety of toxicants with advantages including low cost, reproducibility, low variability and sensitivity.     

Responses of the mussel Mytilus edulis to copper and phenanthrene: Interactive effects

Most investigations of the responses of marine organisms to xenobiotics have concentrated on single contaminants and little is known of possible interactive effects of different classes of xenobiotics. As these latter seldom occur in environmental isolation, it is important to understand any interactions (synergistic or antagonistic) which may occur. This problem has been approached in the mussel Mytilus edulis by exposing estuarine mussels to copper (20 μg litre⁻¹) and phenanthrene (100 μg litre⁻¹) both individually and in combination, and measuring cytochemical subcellular and physiological responses after 3 days exposure and 3 days and 12 days recovery period. Results showed that mussels accumulated both xenobiotics during 3 days exposure. Depuration of copper was complete in 3 days recovery period, while loss of phenanthrene ranged from 30% to 70% of the concentration reached after 3 days exposure. There were no interactive effects on depuration.Both copper and phenanthrene reduced lysosomal hydrolase latency in digestive cells, and copper appeared to have a synergistic effect in preventing recovery of latency of lysosomal N-acetyl-β-hexosaminidase during the recovery period. There was evidence, in the digestive cells, of an antagonistic effect of copper on stimulation of activity of the microsomal respiratory chain (measured as NADPH-neotetrazolium reductase) by phenanthrene. Stimulation of this system by phenanthrene persisted after 12 days recovery period. There was a synergistic interaction of copper and phenanthrene on elevation of oxygen consumption and ammonium excretion. Clearance rates and scope for growth (physiological condition) were depressed by copper but not by phenanthrene after 3 days exposure.These findings are discussed in terms of known effects of copper and phenanthrene and the interactions are considered in terms of environmental effects measurements.     

Toxicological effects of potash brine on bay of Fundy marine organisms

The acute lethality and sublethal heavy metal contamination potential to marine organisms of a waste brine solution from a potash mining operation were determined. The brine was acutely lethal to marine organisms of the Bay of Fundy, Canada, at concentrations between 47 and 55‰ salinity (96-h LC₅₀ values: threespine stickleback, Gasterosteus aculeatus, 47·7‰; polychaete worm, Nephtys incisa, 52·5‰; blue mussel, Mytilus edulis, lethal to whole animal and reduced ciliary activity of gills above 55‰).The brine diluted to sublethal concentrations (≤40‰) contained manganese (≤ 49·5 ×), copper and zinc (≤ 5·2 ×), lead (≤ 2·6 ×) and cadmium (≤ 0·7 ×) in decreasing order of enrichment relative to control seawater. Copper was accumulated in mussels exposed to these solutions over 44 days to the greatest degree (4 ·4 ×), followed by manganese and lead. Tissue lead concentration reached a steady value within 44 days and cadmium was not accumulated.     

Concentrations of unsubstituted polynuclear aromatic hydrocarbons in bay mussels (Mytilus edulis) from Oregon, USA

Concentrations of fifteen unsubstituted polynuclear aromatic hydrocarbons (PNAH) were measured in Mytilus edulis from two sites in Yaquina Bay, Oregon, USA, during 1979–1980. There were significant differences in PNAH levels between the two populations. The average total concentration in mussels inhabiting the more industrialized bayfront was 986·2 μg/kg compared with 273·9 μg/kg in mussels from a more remote site across the bay. Substantial differences were found in the concentrations of different PNAH in M. edulis examined during this study. The smaller more water soluble, compounds were concentrated to one or two orders of magnitude above the larger, less soluble PNAH.     

Uptake of petroleum hydrocarbons by the Blue Mussel (Mytilus edulis L.) after Experimental Oiling and High Pressure, Hot Water Shore cleaning

High pressure, hot water shore cleaning after an oil spill will release high concentrations of petroleum hydrocarbons to ambient marine ecosystems. The immediate increase of hydrocarbons observed in blue mussels, Mytilus edulis, went from background concentrations of 40 μg/g to 657 μg/g and 533 μg/g at a distance of 3 and 8m respectively from the shore. After two weeks the accumulated oil had decreased by 20–45 %. In comparison natural surf and ice cleaning of shores will only produce a small increase in hydrocarbon concentrations. We recommend that high pressure, hot water cleaning is not used in areas where no special bird or wild life protection is needed.     

Long-term effects of tributyltin compounds on the baltic amphipod, Gammarus oceanicus

Amphipod larvae, Gammarus oceanicus, were exposed for 8 weeks to bis(tributyltin) oxide (TBTO) or tributyltin fluoride (TBTF), or for 5 weeks to leachates from tributyltin-containing antibiofouling paints. No larvae survived 8 weeks' exposure to 3 μg/litre TBTO or TBTF. Differential larval survival occurred during exposure to 0·3 gmg/litre of these same compounds. Paint leachates were shown to cause similar toxicity responses at comparable aqueous tributyltin concentrations. An examination of sublethal responses showed slight decreases in growth for larvae exposed to TBTO and to paint leachates, although responses at tributyltin levels below 1 μg/litre were not marked. Whole-animal oxygen consumption rates were not affected by low tributyltin exposure levels. While these studies demonstrate low level toxicity of tributyltins, effects on oxygen consumption and growth do not indicate a mode of action for these compounds.     

Effect of oil and dispersants on the growth of Mussels

Mussels (Mytilus edulis L.) were exposed to North Sea crude oil, microencapsulated oil and dispersants, singly and in combination, and growth rates measured at 24–48 h intervals.Exposure to microencapsulated pure oil (2·0–2·1 mg litre⁻¹) and to microencapsulated mixtures of oil (2·2−2·5 mg litre^-1+5 % of the different dispersants (FINASOL OSR 5, COREXIT 9527, DISPOLENE 36 S) gave approximately the same reduction in growth rate (80–90%) within 170h.Oil chemically dispersed with DISPOLENE 36 S and a pure oil mechanically dispersed in water were significantly less toxic. In high concentrations (2 mg litre⁻¹) all disperants are toxic, DISPOLENE 36 S ssignificantly more than the others.Mussels exposed for 170 h to microencapsulated oil and to microencapsulated oil dispersant mixtures recovered to control growth within 300 h in clean seawater, while in those given pure oil-in-water suspension, the recovery was slower.It is concluded that the toxicity of oil is mainly related to size and concentration of oil particles, while the effect of 5% dispersants added is negligible.     

Reproductive success, xenobiotic contaminants and hepatic mixed-function oxidase (MFO) activity in Platichthys stellatus populations from San Francisco Bay

To identify some specific effects of organic contaminants on fisheries in an urbanized estuary we compared the reproductive success of starry flounder from San Francisco Bay with concentrations of tissue contaminants and hepatic mixed-function oxidase (MFO) activity. We found significantly lower (P < 0·05) sediment concentrations of total identified polynuclear aromatic hydrocarbons (PAHs) in the less urbanized San Pablo Bay (SP) area (Fig. 1) than in the more urbanized central bay (CB) stations (Table 1). For flounder in early gametogenesis (August and September) the SP fish (n = 20) had significantly lower (P < 0·01) liver concentrations of Aroclor 1260 (0·34 ± 0·14 μg/g) than those at the CB stations: Berkeley (BK, n = 20, 1·6 ± 1·6 μg/g); Oakland (OK, n = 16, 2·3 ± 2·8 μg/g); and Alameda (AL, n = 4, 2·2 ± 1 μg/g). A similar pattern existed for DDT concentrations: SP = 0·2 ± 0·16 μg/g; BK = 0·1 ± 0·34 μg/g; OK = 0·4 ± 0·53 μg/g; and AL = 0·4 ± 0·33 μg/g. Total PAHs in livers were as follows: SP = 0·14 μg/g; BK = 2·6 μg/g; OK = 1·4 μg/g; and AL = 14 μg/g. Although gonad index, liver index, and presence of fin rot are inversely related to aryl hydrocarbon hydroxylase (AHH) activity, healthy fish in a similar reproductive state have lower AHH activities in the SP area. For example, in August and September, 1984, mean AHH activities were as follows: SP = 203 ± 89, and CB = 355 ± 200 pmol 3-OH-B[a]P mg microsomal protein min. We found a log-linear relationship for AHH activity and its percent inhibition by 7,8-benzoflavone (10⁻⁴m) and only a few fish from SP showed enhanced AHH activity after addition of 7,8-benzoflavone. This suggests that most of the starry flounder in San Francisco Bay are induced.     

Evidence on the interaction of mercury and selenium in the shrimp Palaemon elegans

The interaction of selenium with mercury was studied in the shrimp Palaemon elegans. The release of ²⁰³HgCl₂ (5·0 μg Hg per gramme body weight) from shrimp pretreated with selenium (SeO₂ doses of 1·97, 3·95 and 7·90 μg Se per gramme fresh weight) was significantly decreased compared with the control group to which only 5·0 μg Hg/g had been administered.In the presence of HgCl₂ (5·0 μg Hg per gramme fresh weight) the release of ⁷⁵Se also diminished significantly at the higher stable Se pretreated dose (7·90 μg Se/g) while, at a lower selenium concentration, the release was not statistically different. Analyses for stable Hg and Se confirmed the decrease in rate of selenium loss in the presence of mercury which had been demonstrated with radiotracers.A dose of 7·9 μg Se per gramme fresh weight injected 12 h before exposure of the shrimp to the various mercuric chloride solutions did not produce a significant difference in the 24 h LC₅₀ compared with the group not pretreated with selenium. However, during exposure to mercury at 3·8 mg/litre, the median lethal time (LT₅₀) for the shrimp pretreated for 4 days with sublethal selenium (6·9 and 10·5 mg Se/litre) was delayed (19·2 and 33·2 h) compared with the group which was not pretreated. The results are discussed in relation to the role of selenium in the acutely toxic effects of inorganic mercury.     

Metallothionein and heavy metal levels in rainbow trout (Salmo gairdneri) during exposure to cadmium in the water

Rainbow trout were exposed to 200 ppb cadmium in the water during four months at 5°C. The liver, kidney and gills were analyzed for cadmium, copper, zinc and metallothionein. Cadmium accumulated in all three organs and reached the highest concentration in the kidney. The zinc and copper concentrations were not altered during the experiment. The metallothionein concentration was significantly higher in liver of exposed fish than in control fish after three months. The kidneys reached significantly elevated levels of metallothionein in the exposed group after four months. These results demonstrate that metallothionein is induced by cadmium after exposure to the metal via water.     

Toxicity of copper to three estuarine bivalves

This paper reports on a study of the toxicity of copper to three species of bivalve of commercial food value, Anadara granosa (Linnaeus), Meretrix casta, Deshayes and Crassostrea madrasensis (Preston) inhibiting the Vellar estuary at Porto Novo (southern India). The LC₅₀ values were estimated as 60 μg Cu/litre for A. granosa, 72 μg Cu/litre for M. casta and 88 μg Cu/litre for C. madrasensis subjected to 96-h static bioassay tests after acclimation for a period of four days in the laboratory. The animals selected for study ranged in length from 29 to 44 mm in A. granosa, from 25 to 42 mm in M. casta and from 31 to 115 mm in C. madrasensis. The experiments were conducted at 25% salinity with pH 8·0 ± 0·1 at a temperature of 27°C ± 0·5°C. The revival rates of bivalves which survived exposure to the LC₅₀ concentrations for the 96-h period (when marked and released in the natural environment) were 67% for A. granosa, and C. madrasensis and 83% for M. casta. The LT₅₀ values for the three bivalves at different concentrations of the metal were also calculated.     

Bioavailability and effects of sediment-bound TBT in deposit-feeding clams, Scrobicularia plana

Concentrations of tributyltin (TBT), dibutyltin (DBT), inorganic and total tin have been measured in water, sediments and deposit feeding clams, Scrobicularia plana, from 25 estuarine locations in England and Wales, in order to compare the bioavailability of different forms of the element. Abnormally high tin values in Scrobicularia from harbours and areas of high boating activity testify to the high bioaccumulation potential of organotins, notably TBT derived from anti-fouling paints, relative to inorganic tin.Infaunal deposit-feeding bivalves consistently contain higher concentrations of TBT than other benthic organisms indicating that sediments may be an important route for uptake. Significant correlations between sediment TBT values and residues in clams such as S. plana (r = 0·81, p < 0·001) support this hypothesis. Direct evidence of the bioaccumulation of sediment-bound TBT is provided from laboratory experiments in which Scrobicularia were exposed to TBT in water and in sediments, either separately or in combination. The results of these experiments clearly demonstrate a predominantly particulate component for TBT uptake in clams.The kinetics of TBT accumulation and elimination were studied in Scrobicularia exposed to sediments containing 0·3 and 1·0 μg/g TBT (as tin). Equilibrium concentrations in tissue are approached after 40 days.Sediments containing 10 μg/g TBT are acutely toxic to S. plana, although such concentrations are only likely to occur close to dockyards and large marinas. Preliminary laboratory and field observations suggest however, that clam populations could be affected at TBT concentrations in sediments of 0·3 μg/g and possibly lower.