Conspicuous scarcity of small-bodied benthic turtles in Alligator Snapping Turtle-Macrochelys temminckii (Troost in Harlan, 1835) dominated systems: bycatch patterns across urban and rural waterways

Abstract

Targeted hoop-net trapping of Alligator Snapping Turtles (Macrochelys temminckii) in two urban Texas bayous (Buffalo Bayou, Little Cypress Creek) and two rural Mississippi streams/bayous (Yazoo, Sunflower) from 2020–2025 yielded 872 total captures. Mississippi range-core sites were dominated by M. temminckii (Yazoo: 69.2%; Sunflower: 59.2%), whereas Texas range-edge sites exhibited substantially greater turtle bycatch (Buffalo Bayou: 45.9%; Little Cypress Creek: 56.8%). Small-bodied benthic turtles (genera Sternotherus and Kinosternon) and the Common Snapping Turtle (Chelydra serpentina) were nearly absent across all systems (n = 6 combined). Capture composition differed significantly between site types, with Alligator Snapping Turtles comprising a greater proportion of captures at rural sites and non-target turtle species comprising a greater proportion of captures at urban sites. The consistent scarcity of small-bodied benthic turtles and C. serpentina across both urban and rural systems suggests that factors other than urbanization may be influencing community structure. These patterns are consistent with hypotheses of predator-mediated suppression, competitive exclusion, or both, associated with M. temminckii dominance.