Consumer-mediated transfers of energy and nutrients across ecosystem boundaries can strongly influence ecosystem structure and function. Mobile consumers link habitats by transporting biomass and nutrients during reproduction and dispersal, creating cross-ecosystem subsidies. Carolina bays are shallow, isolated depression wetlands distributed across the Atlantic Coastal Plain of the southeastern United States. Although individually small, these wetlands occur at high densities and collectively can influence biodiversity and nutrient cycling at landscape scales. Carolina bays support diverse amphibian communities and exhibit pronounced interannual variability in hydroperiod, creating conditions for episodic exchanges of biomass and nutrients across aquatic and terrestrial boundaries. Amphibians are well-suited to mediate these exchanges because of their biphasic life cycles. Adults transport nutrients into wetlands during breeding, while juveniles export biomass and nutrients to surrounding terrestrial habitats upon emergence. We tested three hypotheses: (1) amphibian-mediated fluxes constitute a meaningful component of cross-ecosystem nutrient transport, (2) hydroperiod length regulates the magnitude of nutrient and biomass export to terrestrial systems, and (3) amphibian life history traits mediate community-level zoogeochemical outcomes under variable hydrologic conditions. We analyzed a long-term amphibian dataset from a single Carolina bay in South Carolina, where amphibian movements have been monitored continuously using a drift fence and pitfall array from 1979 to 2023. Records of amphibian abundance, community composition, body size, egg production, juvenile mass, and adult breeding mortality were integrated with annual hydroperiod data. Species-specific stoichiometric information was used to estimate annual dry mass and elemental fluxes associated with amphibian movements across the aquatic and terrestrial boundary. Amphibian-mediated fluxes exhibited substantial interannual variability, with total export to the terrestrial environment associated with wetland inundation duration. Longer hydroperiods supported greater amphibian production and higher biomass and nutrient export, whereas shorter hydroperiods reduced export and shifted species contributions. Life history traits such as larval development time and body size influenced species-level fluxes, while demographic processes, including breeding mortality, further shaped net outcomes. Overall, Carolina bays function as temporally dynamic zoogeochemical hotspots, where hydroperiod variability governs the strength of animal-mediated nutrient transport. Changes in hydroperiod regimes therefore have the potential to alter both amphibian communities and freshwater–terrestrial connectivity.
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