Toxicity of Some Environmental Pollutants to Marine Crustaceans Artemia Sinica (Anostraca- Artemiidae) and Exopalaemon carinica.pdf

1、Background:
　　 To safeguard the marine environment, there is an urgent need to establish standardized methods to analyze the acute toxicity of pollutants to aquatic organisms. As a first step to establish a simple, i

2、nexpensive and reliable short-term routine bioassay to test the toxicity of some environmental pollutants, in this dissertation, I investigated the usefulness of the brine shrimp Artemia sinica as a test species to study

3、 the acute toxicity of several phenolic compounds and heavy metals. A. sinica was chosen as the test species due to its incessant availability in the form of dry cysts which can be hatched with little effort, and its fle

4、xibility to varied nutrient resources as it is a non-selective filter feeder. I also tested the antioxidant enzyme activities of ridgetail white prawn Exopalaemon carinicauda in response to naphthalene. This species has

5、strong tolerance to the change of environmental factors, hence it is easy to culture them in laboratory; it has a high reproduction capacity with a short reproduction cycle (only two months) and maintains reproductive ca

6、pacity all year round. Thus, it is available for experiments at any time. The evaluation of the acute toxicity of the pollutants was based on the median lethal concentration (LC50s).
　　 Results and Conclusion:
　　

7、 Section l. Bioassays using A. sinica. I examined the acute toxicity of several phenolic compounds and heavy metals to the laboratory cultured nauplii and adults of A. sinica. The results indicated that A. sinica nauplii

8、 could resist a significantly higher concentration of heavy metals compared to phenolic compounds. The toxicity order was n-Nonylphenol (n-NP ) □ 4-t-Octylphenol (4-t-OP)□ 2-4-dichlorophenol (2-4- DCP) □ bisphenol-A (BPA

9、) for phenolic compounds, and Cu (CuSO4·5H2O) □ Cr (Na2CrO4)＞ Cd (CdC12·2.5H2O) Pb [Pb(CHCOO)2·3H2O] for heavy metals.
　　 Another bioassay was also conducted on the acute toxicity of five phenolic compounds to the 15

10、 day-cultured A. sinica. The toxicity order of the phenolic compounds was n-hexylphenol (n-HP)＞n-NP＞t-butyl phenol (t-BP)＞ 2,-4-DCP＞ BPA. The LC50s of the tested chemicals obtained by regression analysis demonstrates the

11、 dependency of the responses (dose response relationship) to phenolic exposure. A significant difference of toxicity (LCso) values was recorded between and within the groups of five tested compounds. The 24-hr LCso value

12、 revealed that the toxicity of n-HP is 62.4 times to that of BPA, 5.5 time to t-BP, 4.1 and 2.7 times to 2,-4-DCP and NP, respectively.
　　 I also evaluated the effectiveness of the chorion of A. sinica cysts (shell)

13、as a barrier against nonylphenol exposure. Both whole and decapsulated cysts were exposed to seawater containing 5μgL-1 nonylphenol during their hydration and hatching phase. The concentration of nonylphenol was found hi

14、ghest in the exposed decapsulated cysts, then in the whole cysts, and lowest in the embryos with the chorions removed. These results indicated that nonylphenol was blocked by the shell.
　　 Section 2. Bioassay using E

15、xopalaemon carinicauda. I examined the antioxidant enzyme activities in Exopalaemon carinicauda in response to naphthalene. The aim of this experiment was to evaluate the effect of different concentrations of naphthalene

16、 on the antioxidant defenses in cephalothorax ofjuvenile shrimp E. carinicauda. This is the first report of the cephalothoraxic antioxidant response of shrimps to naphthalene exposure. The shrimps were exposed to six dif

17、ferent concentrations. Groups of naphthalene (160-318 μg/l) for 4 days and then cephalothoraxic tissues were dissected for measurement of the activities of antioxidant enzymes including Catalase (CAT), Superoxide Dismuta

18、se (SOD), Glutathione S-transferase (GST) and Glutathione Peroxidase (GPx); CAT responded to naphthalene exposure significantly in Group 3 (p<0.05) and 4 (p<0.01) and reached the maximum in Group 4 with an activation rat

19、e up to 38.4％. SOD was also induced significantly by naphthalene in Groups 2, 3 and 4 (p<0.05) and highly significantly in Group 5 (p<0.01) with an induction rate of 23.5%. The activity of GPx was not greater in the expo

20、sed shrimp and the response was similar between Groups 3, 4, 6, and 7, but the activity was significantly affected only in Group 5 (p<0.05), with an activation rate of 35.6%. Similarly, GST activity was induced highly si

21、gnificantly (p<0.01) only in Group 4 with an activation rate up to 42.2%. Thus, all of the above antioxidant defense enzymes are inducible enzymes; however, when the animals were exposed to a higher exposure concentratio