Research On Seashells Quality And Activity In Tianjin Nearshore Waters Of The Bohai Gulf In China

Due to marine molluscs' special habitat, life characteristic, and the ability of tolerance and accumulation to chemical and biological toxins in the marine environment, shellfish is often used as a biological indicator of marine environment. In recent years, with the continuous development of land reclamation in the offshore industry of Tianjin, more and more expansion, various kinds of waste inflowing into Bohai, resulting in the pollution of coastal waters, not only causes the shellfish contamination, but also leads to death and migration of shellfish populations, due to the diffusion of suspended matter blowing filling and accumulation. In order to find out the pollution status and the main pollution factors of the shellfish in Tianjin coastal, determine the dredgerfill buried ecological pressure on benthic shellfishes, shellfish samples which collected from Tianjin nearshore waters of the Bohai Gulf in China, which including Scapharca subcrenata, Ruditapes philippinarum, Sinonovacula constricta, Rapana venosa, Meretrix meretrix, Ostrea cucullata, Mactra veneriformis, and Neverita didyma in this local scienctific research.As quality investigation, based on GB 17378.6, the specification for marine monitoring detection method, tested 56 biological samples of 8 species on petroleum hydrocarbon, heavy metals, fecal coliform bacteria, paralytic shellfish poisoning(PSP), diarrhetic shellfish poisoning(DSP) pollution. Three analysis methods, include single factor pollution index method, Nemerow index method and principal component analysis(PCA) were used to evaluate the testing data. The results show that, chemical pollution factors of petroleum hydrocarbons, Cu, Zn, Pb, Cd, Hg, As were detected positive, biological pollution factor of fecal coliform bacteria and DSP were also positive. The results showed that seashells of Tianjin nearshore waters in the Bohai Gulf were not obviously polluted, but Ostrea cucullata is the one of highest contaminative level of all.As activity testing,in order to evaluate the burying effect of Nangang industrial zone dredge material on different macrobenthos, we selected Scapharca subcrenata(SS) and Mactra veneriformis(MV) to test. 4 and 2 types of shell length SS and MV were tested in this experiment respectively to observe survival rates under different burial depths(0cm, 2cm, 4cm, 6cm, 8cm, 10 cm, and 12cm). Results showed that these two kinds of shellfish, especially Mactra veneriformis could survive by vertically migrating out of the dredging material surface. In 8d experimental observation data analysis proved that there was significant correlation between burial depth and mortality(P<0.01).The LC50 of 1~2cm SS is 4.8cm, 95% CI is 2.9~6.7cm, LC50 of 3cm SS is 5.0cm, 95% CI is 3.5~6.5cm, LC50 of 4cm SS is 5.7cm, 95% CI is 4.9~6.5cm, LC50 of 5cm SS is 6.4cm, 95% CI is 5.6~7.3cm; LC50 of 2cm MV is 6.4cm, 95% CI is 5.1~7.6cm, LC50 of 4cm MV is 6.9cm, 95% CI is 6.0~7.8cm.Generally, seashells which in Tianjin nearshore waters of the Bohai Gulf were not obviously contaminated. Activity testing proved that the burial depth was an important factor for the survival of the tested species and their migration capability. Once marine ecosystem is destroyed, it needs a long time to reconstruction and recovery. Furthermore, the appropriate approach to deal with this problem, besides working avoids high density of biological population area; releases dominant species could also contribute to ecological restoration, further more productivity and biological integrity of entire system.