| Macrobenthos was investigated for three times in the Liao River in October 2012, May 2013 and September 2013 in this study. Based on the data obtained, the community structure characteristics of macrobenthos including abundance, species composition, biomass and biological density were analysed, and three biological diversity indices were used to evaluate water quality of the Liao River. In addition, Corbicula fluminea was exposure to anatase titanium dioxide nanoparticles, and titanium contents and oxiditative stress in various tissues were measured. The main results are as follows:1. The species of macrobenthos in the Liao RiverThree times investigation showed that the number of macrobenthos species was small overall in the Liao River. The proportions of various macrobenthos groups were similar, and the main group was the arthropod, followed by the annelid. The community structures of macrobenthos were different at various sampling sites. There was high species abundance at the middle reaches of the Liao River, followed by the upper reaches, and then by the down reaches, where there was nearly no distribution of benthos animals. In 2012 to 2013 three sampling times, the number of arthropod species decreased and the number of annelida species increased.In total, 52 species of macrobenthos(belonging to 41 genera in 25 families) were collected in October 2012. Of the macrobenthos, the arthropoda was most abundant and contained 32 species(accounting for 61.54% of the total), the Annelida included 13 species(25.00%), the mollusk included five species, and other groups included two species. In May 2013, a total of 47 species of macrobenthos(belongs to 30 genera in 9 families) were collected, of which there were 29 species(61.70%) in the arthropoda, 16 species(34.04%) in the Annelida, and two species in the mollusk. In September 2013, a total of 43 species of macrobenthos(33 genera in 15 families) were collected, of which there were 20 species(46.51%) in the arthropoda, 17 species(39.53%) in the Annelida, and five species(11.63%) in the mollusk.2. The mean density and biomass of macrobenthos at each sampling site in the Liao RiverThe mean density and mean biomass of macrobenthos for various sampling sites were from 10.80 ind./m2 to 936.21 ind./m2 and from 0.0062 g/m2 to 101.9287 g/m2 in October 2012. In May 2013, the mean density and mean biomass of macrobenthos for various sampling sites were 0.00 ind./m2~1442.83 ind./m2 and 0.0000 g/m2~42.2356 g/m2, respectively. In September 2013, these two statistics were 0.00 ind./m2~1863.66 ind./m2 and 0.0000 g/m2~66.7397 g/m2, respectively.3. The water quality of the Liao River evaluated based on biotic indices of the macrobenthosBased on the water quality evaluation standard of biotic indices, Shannon-Wiener diversity indices indicated that the percents of sampling sites with heavy pollution were respectively 15.00%, 41.38% and 44.83% for three times of macrobenthos investigations in the Liao River from 2012 to 2013, and the percents of sites with moderate pollution were 50.00%, 44.83% and 27.59%, respectively. Margalef abundance indices revealed that the percents of sites with heavy pollution were 55.00%, 55.17% and 62.07%, respectively, and the percents of sites with moderate pollutionwere 45.00%, 41.38% and 20.69%, respectively. Goodnight-Whitley indices indicated that the percents of clean sites were 45.00%, 34.48% and 20.69%, respectively.4. Bioaccumulation and effects of exposure to anatase titanium dioxide nanoparticles on oxiditative stress in Corbicula flumineaThe changes of titanium bioaccumulation and oxidative stress in Corbicula fluminea were investigated while exposure to anatase titanium dioxide nanoparticles(Ti O2-NPs) in order to evaluate toxicity effects of Ti O2-NPs. After exposed to 5mg/L, 50mg/L and 100mg/L Ti O2-NPs solutions for 24 h to 192 h, the titanium concentration and enzyme activities of glutathione S-transferase(GST) and superoxide dismutase(SOD) in gill, digestive gland and foot muscle tissues of C. fluminea were measured. The results are as follows:At the same exposure time, average titanium contents in the three tissues of C. fluminea in the three Ti O2-NPs concentration groups were significantly higher than the blank control group respectively(P < 0.05). With the exposure time extension, the average titanium contents in the digestive gland and foot muscle tissues were on the rise as a whole in the three Ti O2-NPs concentration groups, and the titanium contents in the digestive gland were higher than those in the foot muscle, whereas the average titanium contents in the gill tissues were at a stable level in the low and medium Ti O2-NPs concentration groups.At the initial stage of Ti O2-NPs exposure, GST enzyme activities in the three tissues increased in different degree. With the exposure time extension, the GST activities in the gill and digestive gland tissues rose again after a decline, whereas the GST activities in the foot muscle tissues gradually decreased.(3) After exposure for 24 h the SOD activities in the gill and foot muscle tissues increased obviously in the three Ti O2-NPs concentration groups, so did the SOD activity in the low concentration group. With the exposure time extension, the SOD activities in the three tissues gradually declined respectively, and the declining range showed a positive correlation with the treatment concentration of Ti O2-NPs. Therefore, the exposures to the three concentrations of Ti O2-NPs will lead to significant titanium bioaccumulation and oxidative stress in C. fluminea, and has obvious toxic effects on this species. |
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