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1.
Short-term (6 h) behavioural responses and mortality of Scrobicularia exposed to low concentrations of copper in sea water (31%, S) have been investigated.Scrobicularia can detect copper at a concentration of 0·01 ppm. The initial response is valve closure resulting in a rapid drop in heart rate. In concentrations of 0·05, 0·01 and, to a lesser extent, 0·1 ppm copper added to sea water, the clams begin to interact with the polluted water after 2–3 h. In 0·5 ppm, the valves remain closed and the heart rate is maintained at a low level over the 6-h exposure period.Mortality increases with time in 0·5 ppm copper concentration, reaching 50% in 5–7 days. In 0·05 and 0·01 ppm, no mortality was recorded over this period.There is an increase in mantle cavity water calcium concentration after 6 h in 0·5 ppm, in contrast to 0·1, 0·05 and 0·01 ppm. Aspects of anaerobiosis, accumulation of heavy metals and survival are discussed in relation to the behaviour of Scrobicularia exposed to various copper concentrations.  相似文献   

2.
Oxygen consumption rates (V?o2) in the grass shrimp Palaemonetes pugio were determined after a 32 day exposure to fluctuating temperatures (FT) (18–22°C) and/or dimethylnaphthalene (DMN)-contaminated food (0·24 μg DMN g wet wt?1) and again after a 16 day recovery period of stable temperatures (20°C) and uncontaminated food. Ingestion of DMN-contaminated food for 32 days resulted in elevated V?>o2 in shrimp exposed to declining oxygen concentrations. After the 32 day exposure period, FT had no significant effect on V?o2 at 15, 20 and 25°C, tissue V?o2 and V?o2 in declining oxygen. Hemolymph copper concentrations were significantly depressed in shrimp exposed to DMN-contaminated food. After the 16 day recovery period, shrimp from the FT regime exhibited depressed V?o2 when exposed to 25°C but not to 15°C. These depressed respiratory rates were offset by the stimulatory effect of DMN-contaminated food.These respiration studies were generally unproductive in explaining the previously reported effects of FT and DMN-contaminated food on the survival of P. pugio under hypoxic conditions.  相似文献   

3.
Sensitivity of larval Paralithodes camtschatica and Eualus suckleyi exposed 20 min–96 h to the water-soluble fraction (WSF) of crude oil was determined. Swimming cessation in half the animals occurred within 20 minutes' exposure to 2 ppm WSF for shrimp larvae and only 0·5 ppm for crab larvae. Half the larvae of both species died after 6 hours' exposure to 8 ppm or 24 hours' exposure to 2–4 ppm, but deaths did not occur until several days after exposure ended. In the field, most non-swimming larvae would probably die as well.  相似文献   

4.
The concentration of Ni in C. edule ranges from 17·8 μg/g to 53·82 μg/g with the highest concentration in the gills and mantle and the lowest in the foot and adductor muscles. The concentration does not change with either size or season.There is no significant increase in mortality even in the highest Ni concentration (100 μg/litre), nor is body condition correlated with experimental Ni concentrations. The rate of uptake of Ni (y) is described by the equation:
y=?16·903+11·674x1+0·437x2
where x1 = Ni concentration (μg/litre) and x2 = time (h).The respiration rates did not significantly change up to the highest Ni concentration used (1000 μg/litre).It is postulated that the main pathway for Ni uptake is through the gills, possibly through mucus sheet or transmembrane absorption, with a secondary uptake route via the viscera.C. edule may therefore be a suitable indicator species for Ni.  相似文献   

5.
Five geographically and genetically diverse strains of the brine shrimp, Artemia salina, were tested for response to copper sulphate. Mean survival times (MST) were determined for each strain following continuous exposure to concentrations of 10?1, 1, 101, 102, 103, 104 and 105 ppm CuSO4. In addition, lifetime reproductive performance parameters were evaluated for 15 females from each strain after 24 h exposure to 0·067 × 10?9 CuSO4.Two-factorial ANOVA revealed that treated females produced fewer offspring per brood and fewer broods per female, resulting in an overall decline in the mean number of offspring per day per female over the reproductive span. When the standard 24 h MST results are compared with the 24 h dose level of CuSO4 found to impair reproductive performance, the latter was from 24,000 to 156,000 times more sensitive, depending upon strain.  相似文献   

6.
Total, chemical and biological oxygen demand of intertidal sediment cores from 12 stations in a mangrove swamp in southern Africa were measured under mean temperature and salinity conditions. In addition to measuring oxygen removed from water overlying cores, the uptake of oxygen from air overlying sealed cores was also determined. Total oxygen consumption ranged from 2·9 to 37·0 ml O2 m?2 h?1 in water and from 22·1 to 81·6 ml O2 m?2 h?1 in air. Chemical oxygen demand usually equalled or exceeded the total, underlining problems in the measurement of this parameter. Since oxygen is not present below a few millimeters in the sediment, it is concluded that oxygen diffusing from the overlying water or air is rapidly utilized at the surface and its uptake rate does not give any measure of metabolic activity deeper down. The oxygen content of the overlying water present during high tide may drop to relatively low levels due to this demand.  相似文献   

7.
The addition of stock copper and zinc nitrate solutions to filtered seawater (pH 7·91) resulted in a large pH shift which was more pronounced with copper. The pH shift was minimized by increasing the buffering capacity of seawater using 10 mm Tris-Tes pH 7·91. Subsequent experimentation was carried out in both unbuffered and buffered seawater.In unbuffered seawater, both copper and zinc had a pronounced inhibitory effect on Mytilus edulis sperm respiration with 50% inhibition occurring at 0.65 mm (41·3 ppm) copper and 1.0 mm (65·4 ppm) zinc. Egg respiration was also inhibited by copper with 50% inhibition occurring at 0.9 mm (57·2 ppm) whereas zinc inhibited egg respiration by only 30% at 1·5 mM (98·1 ppm).In buffered seawater, both copper and zinc produced an inhibitory effect on sperm respiration. However, with copper the inhibition was much reduced whereas zinc had tthe same inhibitory effect as in unbuffered seawater. In contrast to unbuffered seawater, egg respiration was stimulated by copper but zinc produced a comparable respiratory inhibition. The uptake of both copper and zinc in sperm and egg in buffered seawater increased with increasing metal concentration. Metal ion uptake, when expressed as ng ions μl cell volume?1, was approximately 3-fold greater in the sperm than in the eggs and in both cases zinc uptake exceeded copper uptake.At a seawater pH of < 7·5, in the absence of copper or zinc, the respiration of both egg and sperm was inhibited. The maximum levels of inhibition at pH 5·4 were 15% and 30% for sperm and egg, respectively.The differing actions of copper on egg respiration in buffered and unbuffered seawater appear to be due to enhanced copper uptake in unbuffered seawater.  相似文献   

8.
The toxic effects of certain heavy metals (Hg, Cd, Se, As and Pb) on Scylla serrata, the common edible Indian marine crab, are evaluated. Mercuric chloride, phenyl mercuric acetate (PMA), cadmium chloride, selenium dioxide, arsenic trioxide and lead nitrate were tested individually in laboratory static bioassays using artificial seawater to determine the 24 to 96 h LC50 values. As indicated by 96 h LC50 values PMA was found to be the most toxic and lead nitrate the least toxic. CdCl2 showed a 6·6 fold increase in toxicity with increase in the time of exposure from 24 to 96 h. Marked histopathological changes were noticed in the hepatopancreas and gill of Scylla serrata exposed to acute 96 h LC50 values of these metal compounds. 30 days' long-term exposure to sublethal concentrations of mercury and cadmium brought about degenerative changes in the hepatopancreas and gill of exposed animals. Extensive cellular proliferation (hyperplasia) of secondary lamellae accompanied by cyst formation and necrotic regions were often seen in the gills of cadmium treated crabs. Interestingly enough, the free amino acid pool from muscle and hepatopancreas of treated animals, either after acute or long-term exposure, did not show any reduction in number or quantity  相似文献   

9.
Three species of estuarine invertebrates, Palaemonetes pugio (grass shrimp), Pagurus longicarpus (hermit crab) and Argopecten irradians (bay scallop), were exposed to Cd in flowing seawater at concentrations of 0·06, 0·12, 0·25, 0·5 and 1·0 mg/litre. Incipient LC50 values of 0·53 and 0·07 mg/litre were estimated for bay scallop and hermit crab, respectively. The toxicity curve for grass shrimp had not stabilised, but the incipient LC50 value was estimated to fall within a range of 0·2 to 0·3 mg/litre. Short-term response, as measured by time to 50% mortality at the highest Cd concentration, was 10, 21 and 23 days for the bay scallop, hermit crab and grass shrimp, respectively. Scallop growth was inhibited at all exposure concentrations with a measured 42-day EC50 value of 0·078 mg/litre Cd. Byssal thread detachment precedes death in bay scallops. An EC50 value of 0·54 mg/litre Cd for byssal detachment was measured on day 8 of the bioassay before appreciable mortality. This compared favourably with the incipient LC50 value of 0·53 mg/litre Cd. Cadmium accumulation occurred at all concentrations in bay scallop and grass shrimp.  相似文献   

10.
We conducted a study that shows that light and dark conditions do not affect the uptake rates of ammonium and nitrate by the seagrass Zostera noltei. This is an important advantage over some seaweed species in which these rates are severely reduced at night. In the light, the ammonium uptake rates were initially higher (15 and 20 μmol·g?1·h?1) and stabilized at a rate of 5 μmol·g?1·h?1 after 1 h, whereas in the dark the rates remained constant at a rate of 10 μmol·g?1·h?1 over the first 180 min of incubation. The rates of nitrate uptake in the light were high within the first 120 min of incubation (7.2–11.1 μmol·g?1·h?1) and decreased afterwards to lower values (0.8–3.9 μmol·g?1·h?1), whereas in the dark the rates fluctuated around 0.0–11.1 μmol·g?1·h?1 throughout the whole incubation time (7 h). The soluble sugar content of Z. noltei leaves increased significantly with both ammonium and nitrate incubations in the light, indicating the metabolic outcome of photosynthesis. In the dark, there was no significant variation in either the soluble sugar or in the starch content of leaves, rhizomes or roots in either the ammonium or nitrate incubations. However, the total starch content of plants decreased at night whereas the total soluble sugars increased, suggesting a process of starch catabolism to generate energy with the consequent production of smaller monosaccharide products. The starch content of rhizomes decreased significantly during the light incubations with nitrate but not with ammonium. These results suggest that carbohydrate mobilization is necessary for Z. noltei to account for extra energetic costs needed for the uptake and assimilation of nitrate. Furthermore, our results suggest that nitrate uptake, at least during the day, requires the mobilization of starch whereas the uptake of ammonium does not.  相似文献   

11.
The bivalves Protothaca staminea and Mytilus edulis were exposed to five depths of decomposing bark from an active log transfer facility for 13–96 days in a field experiment at Auke Bay, Alaska. Survival and condition of both species was inversely related to depth and duration of bark coverage. As little as 6 cm of bark reduced survival; survival declined most rapidly between 10 and 15 cm of bark. The depths of bark under which half the animals died after 96 days of exposure were 12·8 ± 1·6 cm for P. staminea and 10·9 ± 1·5 cm for M. edulis. Interstitial water in the bark deposits had low concentrations of dissolved O2 (2·5–5·3 mg/liter) and elevated concentrations of hydrogen sulfide (1·0–8·1 mg/liter total sulfide) and ammonia (46–131 μg-at N/liter) compared to the surface water from the control treatment. Survival of P. staminea and M. edulis was inversely related to concentrations of hydrogen sulfide and ammonia and directly related to dissolved O2 concentrations.  相似文献   

12.
Exposure of the crab Cancer productus to chlorinated seawater resulted in alterations in haemolymph sodium and magnesium concentrations. At the highest chlorination levels, which approached the 96-h LC50, regulation of both ions was essentially abolished. Reciprocal changes in the sodium and magnesium levels suggested an effect on the activity of the bladder wall, which has been implicated in the regulation of haemolymph magnesium in crustaceans.Additionally, exposure to 1·19 μg/ml applied Cl (0·68 μg/ml TRO) for 96 h resulted in a fourfold increase in the ammonia excretion rate. Crabs also contributed considerable chlorine demand to the exposure seawater. Measurements of TRO in the inhalant seawater and water exiting the crabs' branchial chambers indicated a reduction in TRO equivalent to 57% of that initially present in the inhalant water (0·51 μg/ml TRO).Measurements of ammonia concentrations in the exposure water indicated that ammonia in seawater was consumed in reactions with oxidants. This was especially evident at higher levels of chlorination. At 0·58 μg/ml applied Cl and above, chlorination resulted in near disappearance of ammonia from the water.  相似文献   

13.
An in situ chamber of volume 3881 and bottom area 0·64 m2 was used to determine the flux of oxygen and inorganic nutrients across an estuarine sediment-water interface over a 65-day period. Over the first 7 days, oxygen uptake was 378 mg m?2 day?1 and the rates of ammonium and phosphate release were 2·22 and 0·34 mg at. m?2 day?1, respectively. The water became anoxic in 14 days.The rates of flux in a similar chamber containing only detritus recently settled from the water column were 371 mg m?2 day?1 (oxygen), 1·66 mg at. m?2 day?1 (ammonium) and 0 12 mg at. m?2 day?1 (phosphate), demonstrating that detritus contributes substantially to exchange across the sediment-water interface.The evolution of the two chambers was similar over the latter part of the experimental period. A third chamber containing only water exhibited very minor changes.The role of detritus in nutrient recycling at the sediment-water interface is discussed in relation to the productivity of shallow water bodies such as the estuary in which the experiment was conducted, which itself undergoes periodic deoxygenation during prolonged stratification. The measured flux of nitrogen across the interface was found to represent approximately 31% of the mean daily phytoplankton requirement.  相似文献   

14.
Behavioral responses to chemically dechlorinated seawater were studied using two species of marine fish associated with power plant discharge areas off Southern California. Opaleye (Girella nigricans) neither avoided nor were attracted to chlorinated seawater containing 0·1 mg/liter total residual oxidants (TRO) which had been dechlorinated using equimolar or excess sodium thiosulfate. Blue-banded goby (Lythrypnus dalli) did not avoid dechlorinated seawater initially containing 0·1 or 0·9–1·0 mg/liter TRO. Previously it has been shown that opaleye avoided chlorinated seawater with oxidant concentrations of 0·1 mg/liter and blue-banded gobies avoided 0·9–1·0 mg/liter TRO. Elimination of chlorine-produced oxidants by thiosulphate dechlorination resulted in 100% survival in both species. The toxicological implications of exposure to dechlorinated seawater are discussed.  相似文献   

15.
The effects of the dispersant Corexit 9527 and Corexit with crude oil on the rate of glucose uptake and mineralisation were studied in Arctic and Subarctic marine waters and sediments. Essentially all of the 149 water and 95 sediment samples tested displayed decreased glucose uptake rates in the presence of either 15 or 50 ppm Corexit. Depressed uptake rates were observed at concentrations as low as 1 ppm. The mean concentration at which Corexit depressed glucose uptake by 50% was 12 ppm. The effect of Corexit was more pronounced on pelagic than on benthic microbial populations.  相似文献   

16.
The tropical seagrass Halophila stipulacea is dominant in most regions of the Indo‐Pacific and the Red Sea and was introduced into the Mediterranean Sea after the opening of the Suez canal. The species is considered invasive in the Mediterranean Sea and has been progressively colonizing new areas westward. Growth and photosynthetic responses of H. stipulacea have been described but no information is yet available on the nitrogen nutrition of the species. Here we simultaneously investigated the uptake kinetics of ammonium and nitrate and the internal translocation of incorporated nitrogen in H. stipulacea using 15N‐labelled substrates across a range of Ni levels (5, 25, 50 and 100 μm ). The ammonium uptake rates exceeded the nitrate uptake rates 100‐fold, revealing a limited capacity of H. stipulacea to use nitrate as an alternative nitrogen source. The uptake rates of ammonium by leaves and roots were comparable up to 100 μm 15NH4Cl. At this concentration, the leaf uptake rate was 1.4‐fold higher (6.22 ± 0.70 μmol·g?1 DW h?1) than the root uptake rate (4.54 ± 0.28 μmol·g?1 DW h?1). The uptake of ammonium followed Michaelis–Menten kinetics, whereas nitrate uptake rates were relatively constant at all nutrient concentrations. The maximum ammonium uptake rate (Vmax) and the half‐saturation constant (Km) of leaves (9.79 μmol·g?1 DW h?1 and 57.95 μm , respectively) were slightly higher than that of roots (6.09 μmol·g?1DW h?1 and 30.85 μm , respectively), whereas the affinity coefficients (α = Vmax/Km) for ammonium of leaves (0.17) and roots (0.20) were comparable, a characteristic that is unique among seagrass species. No substantial translocation (<2.5%) of 15N incorporated as ammonium was detected between plant parts, whereas the translocation of 15N incorporated as nitrate was higher (40–100%). We conclude that the Ni acquisition strategy of H. stipulacea, characterized by a similar uptake capacity and efficiency of leaves and roots, favors the geographical expansion potential of the species into areas with variable water‐sediment N levels throughout the Mediterranean.  相似文献   

17.
Low levels of dissolved oil hydrocarbons are demonstrated to produce sublethal effects on the early cod larval stages. These effects are discussed in relation to larval survival through the first critical stages.Continuous exposure of cod eggs and larvae to 0·05 and 0·25 ppm of the water-soluble fraction (WSF) of Ekofisk crude oil for 14 days caused significant reduction in growth and change in neutral buoyancy. The larvae exposed to 0·25 ppm showed malformation in the foremost part of the head and jaw, which reduced their ability to capture prey organisms at first feeding.  相似文献   

18.
Concentrations of Hg, Zn, Fe, Cd and Cu in the muscle tissues of a dogfish, Squalus mitsukurii, were determined by atomic absorption spectrometry and found to be in the ranges of f0·019–2·13, 1·8–3·6, 1·5–5·7, 0·001–0·018 and 0·12–0·70 μg/g wet weight, respectively. The frequency distributions of concentrations, with the exception of mercury, were found to be log-normal. The correlation coefficient between mercury content and total length was positive and large and statistically highly significant. For other metals negative correlations were observed. Mercury concentration in the muscle was found to increase in proportion to the total length cubed. Regression of mercury concentration on age of sharks was shown to be linear. Analysis of covariance showed that the difference between sexes was not statistically significant, either in slope or in height. The concentration of mercury in the muscle tissues of embryos was considerably lower, Cd roughly the same and Zn and Fe higher than those of mothers. The concentrations of Zn, Fe and Cu are higher in the embryonic stage and immediately after birth than in later stages of growth.  相似文献   

19.
Summary

Lake Pupuke, situated in the North Island of New Zealand near Auckland (Latitude 36° 53'S, Longitude 174° 52'E), is a small, circular body of water (maximum width 1.2 km, maximum depth 55 m). From November 1966 to November 1967 observations on its physico‐chemical factors were made twice monthly.

The range of temperatures in the year was 12.0–24.2°c at the surface and 11.3–14.5°c at 40 m. A thermocline farmed between early October and early January, when it became strongly developed at about 17 m and persisted until late April. Between early May and late June the stratification was breaking down and between mid July and mid September the lake was isothermal.

The values for light transmitted per metre through the water were high from mid August to mid December (53–76% per metre), very low from mid December until mid February (23–49% per metre), high in March (75% per metre) and relatively constant over the winter months (53–64% per metre). The amount of light transmitted depended closely on the density of phytoplankton. Changes in the depth at which a Secchi disc disappeared paralleled the light transmission values, and the mean Secchi depth was 2.2 m, range 1.0–5.2 m.

Oxygen concentrations down to 30 m were highest at all depths from mid November to early January (112–134% saturation). From early January to late April oxygen was strongly stratified (epilimnion 55–100% saturation, hypolimnion 24–77% saturation). During winter oxygen values gradually increased at all depths.

The range of pH was 7.8–9.5 units at the surface and 7.8–8.6 units at 30 m. From early January to late April pH values were strongly stratified but from mid July to mid August they were nearly uniform. The range of alkalinity (mainly HCO3 ? ions) was 76.0–80.8 ppm CaCO3 and values showed stratification in summer. Carbonate ion was present from early October to mid June, but free carbon dioxide was only found in trace amounts.

The range of nitrate ion concentrations was 0.05–0.31 ppm; nitrate became obviously depleted in summer. Only one nitrite value was significant, 0.25 ppm. other nitrite values never exceeded 0.10 ppm. The concentration of ammoniacal nitrogen built up to a summer maximum of 0.95 ppm in the hypolimnion (annual range 0–0.95 ppm); values for albuminoid ammonia (0.016–1.03 ppm of nitrogen) varied with the quantity of living matter present.

The annual mean for total ion concentration (3.30 meq./1) was high and the order of ions was Na+>Mg2+>Ca2+>K+ and HCO3 ?>CI?>SO4 2?. Such dissolved salts may have arrived as airborne particles, dissolved in rain, or as sea spray.  相似文献   

20.
The rotatory-flow technique was applied to cod, Gadus morrhua L., from different regions of Scandinavia. Fish from three area (Vikanes, Norway and Kristineberg and Gårdby, Sweden) in which the water is relatively unpolluted did not differ significantly as to the mean reaction quotient. Experiments to determine the fitness of cod from the Kristineberg and Stenungsund areas were conducted during a 29-month period. The mean reaction quotients for Stenungsund cod were significantly lower than those for Kristineberg cod for all the experiments except for the final tests conducted during November, 1975. They did not vary inversely to the amounts of monomethyl mercury, PCB and DDT analysed in the trunk muscles of tested specimens.In order to determine the effect of these toxic compounds on the efficiency of the fish from Kristineberg, cod were treated with sublethal doses given by oral intubation. A significant decrease in the reaction quotients was obtained with the lowest level of DDT used (1 ppm), the decreases in the reaction quotients being linearly correlated (r = 0·60) with the amount of DDT in the muscle tissue (mean value 0·36 ppm wet tissue). For PCB and mercury the corresponding mean levels in muscles were 1·8 and 1·5 ppm, respectively. These amounts are about 10, 30 and 75 times greater, respectively, than those found in the Stenungsund cod. It is, however, doubtful whether the distribution of the toxicants within the fish body corresponded to that occurring in the sea.  相似文献   

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