Population Dynamics and Productivity of the Prosobranch Snail Goniobasis Potosiensis

Date of Graduation

Fall 1982


Master of Science in Biology



Committee Chair

Milton Topping


Abundance, growth, and production of Goniobasis potosiensis were studied from March 1981 to February 1982, at three locations in the James River, Missouri. A total of 24,004 snails were collected and measured. The species was univoltine and individuals lived from 19 to 21 months. Recruitment occurred from June to August and followed a progressive wave from upstream down. Mean lengths ranged from 0.7 mm to 13.7 mm with the maximum sized snail being 19.27 mm long. The sex ratio for all three stations was 1.2, with a significant excess of males. No sexual dimorphism in length was found. Growth was interrupted by winter in the coexisting cohorts. Abundance averaged 1179 individuals /sq m and ranged from 0 to 6288. Biomass, computed from length-frequency data using an empirically determined length-weight relationship, averaged 3.77 g ash-free dry wt of live matter /sq m and ranged from 0 to 8.85. Annual production estimates were 10.32, 6.79, and 4.44 g/sq m from upriver to down river. Turnover ratios were 8.25, 3.47, and 4.39 on stations A, B, and C, respectively.

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© Stephen John Flora