Thesis Title

Seed Dispersal by Aquatic Turtles

Date of Graduation

Fall 2003

Degree

Master of Science in Biology

Department

Biology

Committee Chair

Don Moll

Subject Categories

Biology

Abstract

Seed dispersal capabilities by several common aquatic turtles in Southwestern Missouri were investigated. Fecal matter was first obtained during a summer seed survey in which stinkpots (Sternotherus odoratus), river cooters (Pseudemys concinna), spiny soft-shell turtles (Apalone spinifera), and common map turtles (Graptemys geographica) were sampled. Seeds of Agropyron repens, Carex spp., Ludwigia peploides, Polygonum spp., Panicum spp., Ranunculus sceleratus, Setaria spp., and Silene dichotoma were observed in the fecal matter. Following the initial survey the study mainly focused on two omnivorous aquatic turtles, the common snapping turtle (Chelydra serpentina) and the red-eared slider (Trachemys scripta). Large numbers of mulberry (Morus spp.), barnyard grass (Echinochloa crus-galli) and curly dock (Rumex crisus) seeds were observed in the feces of sliders and snappers from a farm pond in Christian County, Mo. Feeding trials were conducted to determine if seeds were being damaged as they passed through the digestive tracts of snappers (n = 10) and sliders (n = 10). The largest amount of damaged seeds passed was mulberry seeds by sliders (median = 34%). Viability of the seeds used in the feeding trial was determined by their percent germination. Results from a chi-square test showed that there was no significant difference between the turtle-passed seeds and controls for mulberry seeds (p = 0.925), but there was a significant difference between the turtle-passed seeds and the control for the barnyard and curly dock seeds (p < 0.001), with the control seeds having a greater percent germination. Although digestion by these turtles does not increase germination of the seeds, these turtles were passing seeds that did germinate. Hence, they are considered to be capable of dispersing mulberry, barnyard grass, and curly dock seeds to areas near pond margins and to more distant locations during overland movements.

Copyright

© Jeffery B Kimmons

Citation-only

Open Access

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