Impact Of Artificial Reef On Meiobenthos Community Structure In Bohai Bay Offshore Area

Sediment samples were collected from 12 stations in Bohai Bay artificial reefs which were built in 2010,2012,2014 and blank area(sea nearby)in September 2014 and July 2015.Analyzed the community structure and distribution of meiobenthos and relation to environmental factors.Results showed that,sediment type was mainly constituted by clayey silt in Bohai Bay artificial reefs area.In September 2014,the average content of chlorophyll a(Chl-a)in surface(0~2cm),middle(2~5cm),and bottom(5~10cm)sediment were 3.02±0.13 mg/kg,2.92±0.24 mg/kg,2.36±0.42mg/kg,and 3.65±0.81 mg/kg,3.2±0.54 mg/kg,2.08±1.17mg/kg as to phaeophorbide a(Pha-a).The average content of TOC was 0.45%±0.074%.The average content of heavy metals Cu,Zn,As,Cd,Cr,Pb was 63.92±17.15 mg/kg,118.58±32.58 mg/kg,26.9±6.88 mg/kg,0.4±0.11 mg/kg,111.97±28.23 mg/kg,93.55±15.76 mg/kg.Spearman analysis showed that,except for Cha-a and TOC have negative correlation,other environmental factors had positive correlation.One-way ANOVA analysis showed that,the content of TOC and 6 heavy metals in artificial reefs area was lower than blank area,and it had significant difference.In July 2015,the results showed that,the average content of chlorophyll a(Chl-a)in surface(0~2cm),middle(2~5cm),and bottom(5~10cm)sediment were 3.02±0.13 mg/kg,2.92±0.24 mg/kg,2.36±0.42mg/kg,1.11±0.16 mg/kg,1.07±0.34 mg/kg,0.71±0.18mg/kg as to phaeophorbide a(Pha-a).The average content of TOC was 0.6±0.25%.The average content of heavy metals Cu,Zn,As,Cd,Cr,Pb is 11.94±1.21 mg/kg,33.4±3.6 mg/kg,5.08±0.54 mg/kg,0.13±0.04 mg/kg,18.94±2.11 mg/kg,9±0.82mg/kg.Spearman analysis showed that,except for Cha-a and TOC had negative correlation,other environmental factors had positive correlation.One-way ANOVA analysis showed that,the content of TOC and 6 heavy metals in artificial reefs area was lower than blank area,and it had significant difference.A total of 7 groups of meiofauna in Bohai Bay artificial reefs area: Nematoda,Copepoda,Palychaeta,Kinorhyncha,Bivalvia,Ostracoda,Priapulida.The average abundance of meiofauna was 1098.66±15.33 ind./10cm2 in Sep 2014,and 755.63±10.96 ind./10cm2 in Jul 2015.It rate to breeding season.The largest abundance of meiofauna was in 2012 artificial reefs in Sep 2014,but in Jul 2015 the largest abundance was in blank area.Free living marine nematodes were the most dominant group in both season,accounting for 96.4% and 92.6%.The meiofauna was mainly found in surface sediment,accounting for 54.1% and 62%.Used the ratio of Nematoda and Copepoda(N/C)and potential ecological risk evaluated the degree of pollution in Bohai Bay artificial reefs.Blank area has a heavier pollution degree,and the earlier built artificial reefs has a lighter pollution degree than the laters.But the sorting coefficient of two methods in different type sediment might be dissused.