Shanghai yufang yixue (May 2024)
Surveillance and trend analysis of snails in Songjiang District of Shanghai from 2007 to 2023
Abstract
ObjectiveTo analyze the monitoring results and trends of Oncomelania in Songjiang District of Shanghai from 2007 to 2023， and to provide reference for future monitoring work.MethodsThe data of snail monitoring in Songjiang District from 2007 to 2023 were collected， including the location of snail spots， the number of survey frames， the area with snails， the number of frames with snails， the total number of snails， etc. The density of living snails and the occurrence rate of living snail frames were calculated.ResultsFrom 2007 to 2023， a total of 158 snail spots were found in 22 administrative villages in 4 towns in Songjiang District， including 131 emerging snail habitats （82.91%） and 27 reemerging snail habitats （17.09%）. The total snail area was 175 980 m2， the number of snail frames was 10 061， and 33 302 snails were captured. The highest density was 260/0.11 m2， and 15 662 snails were dissected. No positive snails were found. The average density of living snails was 0.60/0.11 m2 and the average occurrence rate of living snail frames was 17.99%. The snail areas in different areas were Yexie Town 126 000 m2 （71.60%）， Maogang Town 26 470 m2 （15.04%）， Xinbang Town 17 040 m2 （9.68%）， and Shihudang Town 6 470 m2 （3.68%）. The average density of living snails in different areas was 0.89/0.11 m2 in Yexie Town， 0.65/0.11 m2 in Maogang Town， 0.26/0.11 m2 in Shihudang Town and 0.24/0.11 m2 in Xinbang Town. The snail areas of different snail habitats were as follows： woodland 151 250 m2（85.95%）， river 13 810 m2（7.85%）， ditch 6 910 m2（3.93%）， farmland 4 010 m2（2.28%）. The average density of living snails in different snail habitats： ditch 1.01/0.11 m2， beach 0.86/0.11 m2， woodland 0.57/0.11 m2， river 0.40/0.11 m2. The occurrence rate of living snail frames in different regions and different snail environment types showed a downward trend and the difference was statistically significant.ConclusionAlthough the snail monitoring indicators such as snail area， average living snail density and average living snail frame occurrence rate in Songjiang District are still at its historically low level， the average living snail density and average living snail frame occurrence rate are still high compared with other regions or the national average. We should focus on the upper reaches and tributaries of the Huangpu River， especially the key areas of seedling transplantation， and strengthen monitoring and supervision to reduce the risk of snail input.
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