关键词: 湖北钉螺, 形态, 种群结构, 草本群落, 理化性质, 洞庭湖滩地

Abstract: Objective　To examine the effects of plant communities on Oncomelania hupensis distribution and survival, and the regulatory effects of the microenvironment under plant communities on the morphology and population structure of O. hupensis in marshlands in Dongting Lake. Methods　Seven typical herbaceous plant communities were sampled from marshlands in Dongting Lake in Junshan District, Yueyang City, Hunan Province on June 2024, including Carex scabrifolia, Phragmites australis, Artemisia selengensis, Polygonum viviparum, Alternanthera philoxeroides, Erigeron annuus and Athyrium multidentatum. Sixty plant community quadrats, each measuring 1 m × 1 m, were selected to investigate the plant density, coverage and height in plant communities, and soil physiochemical properties, including soil pH, water content, bulk density, total soil porosity and heavy metal content, and snail population indicators, including total snail counts, count of living snails, snail gender, snail whorl count, snail length, snail width, aspect ratio of snails. The differences in snail population characteristics were compared under different types of plant communities, and the associations of living snail density, aspect ratio and whorl counts with plant population characteristics and soil physiochemical properties were examined. Results　A total of 9 quadrats of C. scabrifolia communities, 12 quadrats of P. australis communities, 9 quadrats of A. selengensis communities, 9 quadrats of P. viviparum communities, 9 quadrats of A. philoxeroides communities, 6 quadrats of E. annuus communities and 6 quadrats of A. multidentatum communities were investigated in June 2024. There were significant differences in the plant height across plant communities (F = 15.06, P < 0.001), with the highest height seen in P. australis communities (129.29 cm ± 26.56 cm) (all P values < 0.01), and there were significant differences in the plant community coverage (F = 4.45, P < 0.001) and density (F = 9.18, P < 0.001). There were significant differences in soil available potassium, available phosphorus, total nitrogen, total carbon, total phosphorus, total potassium, pH, soil water content, total soil porosity, soil bulk density and Mn, Ni, Cu, Zn contents across plant communities (F = 1.15 to 30.69, all P values < 0.05). A total of 836 snails were captured in 60 quadrats, including 546 living snails, with a living snail density of 1.01 snails/0.1 m2. There were significant differences in the living snail density (F = 2.83, P < 0.05) and snail length (F = 6.72, P < 0.05) across plant communities; however, no significant difference was seen in the snail width (F = 4.02, P > 0.05). There was a significant difference in the snail whorl count across plant communities (F = 1.68, P < 0.05), and high proportions of 6⁃, 7⁃ and 8⁃whorl snails were seen in P. australis communities (36.84%, 28/76), C. scabrifolia communities (53.70%, 29/54) and P. viviparum communities(52.03%, 77/148), respectively. The density of living snails positively correlated with herbaceous community density (rs = 0.485, P < 0.05), herbaceous community coverage (rs = 0.417, P < 0.05), total carbon (rs = 0.337, P < 0.05) and soil water content (rs = 0.409, P < 0.05), and the available potassium content negatively correlated with the density of living snails (rs = -0.370, P < 0.05). The aspect ratio of snails positively correlated with total potassium (r = 0.392, P < 0.05), available potassium (r = 0.462, P < 0.05) and total soil porosity (r = 0.424, P < 0.05), and the average snail whorl counts positively correlated with herbaceous community coverage (r = 0.369, P < 0.05) and soil water content (r = 0.423, P < 0.05). Smooth curve fitting revealed that the living snail density gradually increased with an increase in the herbaceous community coverage, with a smooth curve of y = 0.05x2 - 6.65x + 218.81 (t = 43.01, P < 0.05), and the aspect ratio of snails appeared a tendency towards a rise with the increase in total potassium (y = 0.05x + 2.19; t = 1.67, P < 0.05) and available potassium in soil (y = 0.02x + 2.03;  t = 1.20, P < 0.05), and total soil porosity (y = 0.44x + 2.07;  t = 2.13, P < 0.05). In addition, the average snail whorl counts appeared a tendency towards a rise with the increase in the herbaceous community coverage (y = 1.56x + 5.61;  t = 8.48, P < 0.05) and soil water content (y = 0.35x + 5.21; t = 3.01, P < 0.05). Conclusions　Plant communities may affect O. hupensis snail population characteristics by regulating the microenvironment. High coverage, high density and high soil water content are associated with the density and morphology of O. hupensis.

Key words: Oncomelania hupensis, Morphology;Population structure, Herbaceous community, Physiochemical property, Marshland in Dongting Lake