| In order to study the ecological response to water pollution situation, heavy metals(Cu2+)and organic-phosphorus pesticide toxicity(chlorpyrifos) were selected to conducted single and Joint acute toxicity tests to aquatic organisms, Neocaridina denticulate. The corresponding LC50 was acquired and the behavior change of N. denticulate during the experiment was observed; the addition indice methods was used to evaluate the comprehensive toxicity. On this basis, stress test was performed for 5 days respectively to research the change of physiological indices(muscle tissues protein, SOD, MDA and Ach E activity) and toxic mechanism. The rate of oxygen consumption and ammonia of N. denticulate exposed to Cu2+ and chlorpyrifos solutions was measured as a indice to observe the condition of fundamental metabolism. By field investigation, we knew preliminary the status quo of distribution of N. denticulate in Shanghai, and made a research on the relationship between the number of them, individual characteristics indice and water environmental factors. Based on the researches, we confirmed the following results:1.In the study of the toxicity response of N. denticulateto to heavy metals Cu2+ and organ-phosphorus pesticide chlorpyrifos. The results of single toxicity tests showed that the single toxicity tests showed that chlorpyrifos had significantly higher toxicity to N. denticulate than Cu2+(p <0.01). The Cu2+ concentrations for which we observed no effect on N. denticulate(no observed effect concentration, NOEC) and for which we observed the lowest effect(lowest observed effect concentration, LOEC) were 1.78 mg?L-1, 2.40 mg?L-1, respectively.The LC50 of 24 h, 48 h, 72 h and 96 h were 6.41 mg?L-1, 4.75mg?L-1, 4.20 mg?L-1 and 3.44 mg?L-1, respectively. For chlorpyrifos, the NOEC and the LOEC were 0.04 μg?L-1, 0.07 μg?L-1, respectively, the LC50 of 24 h, 48 h, 72 h and 96 h were 0.35, 0.17, 0.11 and 0.06 μg?L-1, respectively. According to fish toxicity grading standards, Cu2+ was highly toxic to N. denticulate while chlorpyrifos was virulent. The comprehensive toxicity tests showed that the joint toxicity of Cu2+ and chlorpyrifos was synergistic when the toxicity was 1:1 at 24 h, 48 h, 72 h and 96 h, and the addition indice(AI) were 0.02, 0.45, 1.86 and 2.23, respectively.2.In the study of the physiological response of N. denticulateto to heavy metals Cu2+ and organ-phosphorus pesticide chlorpyrifos. The results showed that: when exposed to different concentrations of Cu2+ and chlorpyrifos solutions, the muscle tissues protein concentrations were significantly lower with the extension of time to varying degrees. In the lower concentration groups of Cu2+(0.086 mg·L-1 and 0.172 mg·L-1) and the higher concentration groups of chlorpyrifos(0.0060 μg·L-1 and 0.0120 μg·L-1), the total SOD activity showed inhibiting effect; the trend of the higher concentration group of Cu2+(0.344 mg·L-1 and 0.688 mg·L-1) showed "inhibabition-promotion- inhibation", however, the lower concentration groups of chlorpyrifos(0.0015 μg·L-1 and 0.0030 μg·L-1) showed the "inhibition- promotion" changes in trends; MDA contents changed similarly, and within a certain range of concentrations, MDA contents presented gradually rising trend with Cu2+ and chlorpyrifos concentration increasing, which indicated that Cu2+ and chlorpyrifos accelerated lipid peroxidationinmuscle tissues of N. denticulate. In addition, ACh E activity in Cu2+ and chlorpyrifos solutions showed inhibiting effect, and in the higher concentration of Cu2+ and chlorpyrifos solution, the activity was gradually decreased with the increase of concentration, indicating that Cu2+ and chlorpyrifoscs impacted the normal physiological functions of N. denticulate, and the higher the concentration, the greater the damage effect. Based on the analysis results, we confirmed that the total SOD, MDA and ACh E played significant roles as physiological indicators in evaluating toxic effect to heavy metals and organic-phosphorus pesticide of N. denticulate.3. In the study of the acute toxicity response to heavy metals and organic-phosphorus pesticide toxicity of breathing and discharge in aquatic organisms, N. denticulate was exposed to different concentrations of Cu2+ and chlorpyrifos solutions. The results showed that: the trend of the oxygen consumption rate was gradually decreased in Cu2+ and rised in chlorpyrifos solutions(except a little decrease in 0.012 μg·L-1 concentration group) with the increasing of the concentration; the ammonia rate presented a consistent trend, it is that in the ranges of experimental concentrations, the ammonia rate presented gradually decreasing trend with Cu2+ and chlorpyrifos concentration increasing. Based on the result that Cu2+ and chlorpyrifoscs impacted the breathing and discharge functions of N. denticulate, We can take advantage of the rate of oxygen consumption and ammonia of N. denticulate with the change of enzyme activity in their body as a early warning for these two kinds of pollution.4. The resource status quo investigation of N. denticulate about Shanghai in May and July in 2014 presented that N. denticulate mainly appeared in water grass which contained Cabomba caroliniana, Ceratophyllum spp., Hydrilla verticillata, Myriophyllum spicatum, Vallisneria spp., Lemna minor, Hydrocharis dubia and so on. Laboratory analysis showed the sites that the N. denticulate appeared was not completely consistent in May and July. The N. denticulate quantity, water grass biomass and most of the individual phenotypic characters had no significant correlation with the water environmental factors, only the individual traits showed a certain correlation. So if the N. denticulate could be used as a indicator of water quality remained to be explored. |
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