Invasion of American bullfrogs along the Yellowstone River

Abstract

This review examines the ecological, economical, and public health significance of chironomids and provides examples of chironomid invasions via international shipping and the subsequent local and regional impacts. Dispersal and adaptation mechanisms as facilitators of chironomid invasions are presented, and control methods are discussed. Impacts ranged from increased nuisance occurrences to agricultural disruption. Anthropogenic activities including pollution-related decimation of aquatic benthic communities might allow introduction of invasive chironomids. Chironomids can inhabit many environments, including eutrophic lakes and wastewater treatment areas, and may accumulate contaminants in high concentrations. Health concerns include the association of chironomid egg masses with Vibrio cholerae, roles of chironomids as vectors for avian botulism, and effects of chironomid chemicals as human allergens. Therefore, the presence of new chironomid species in an environment may present threats to public health and local ecosystems.

Novel application of explicit dynamics occupancy models to ongoing aquatic invasions

“…This approach resulted in 15 palustrine and 77 riverine sites that were accessible every year, 2012–2016. I also included 14 sites that were previously surveyed for bullfrogs by Montana's Natural Heritage Program (Sepulveda et al., ).…”

“…In the initial and subsequent years of monitoring, encounter surveys were conducted at these sites between the hours of 8:00 and 20:00 for all bullfrog life stages (Sepulveda et al., ). In areas where only post‐metamorphic bullfrogs were encountered, technicians walked along the water's edge to visually search for presence of eggs and larval bullfrogs and made dip‐net (38‐cm diameter) sweeps once every three steps to determine presence of larval bullfrogs.…”

“…In general, deeper waters have greater permanency than shallow waters. Bullfrogs also have a preference for water bodies with emergent aquatic vegetation (Bury & Whelan, ; Sepulveda et al., ), especially for oviposition sites (Liu, Guo, Luo, & Li, ). Because of these associations, I predicted ψ and γ t would be greater and ε t would be lower at sites with larger extents of shallow water and emergent vegetation and at sites with deeper water.…”

“…The bullfrog invasion in the Yellowstone River floodplain is relatively recent and not at equilibrium conditions. Bullfrogs were first documented in a permanent pond adjacent to a Yellowstone River tributary near Billings, MT, in 1999 and at two additional downstream sites in 2005 (Sepulveda et al., ). By 2013, evidence of bullfrog breeding (i.e.…”

“…By 2013, evidence of bullfrog breeding (i.e. eggs, larvae or metamorphs) was detected at 45 sites (Sepulveda et al., ). Natural spread, following initial introduction events, is now likely driving this rapid invasion, as there is no molecular evidence for human‐mediated jump‐dispersal events (Kamath, Sepulveda, & Layhee, ).…”