Fish Mass Mortality Events Trigger Energy Transfer via Invertebrate‐Mediated Pathways at the Aquatic–Terrestrial Interface

Animal mass mortality events are increasing under global change, generating large and unpredictable pulses of carrion that can influence ecosystem functioning. Although scavenger dynamics at individual carcasses are relatively well understood, little is known about how terrestrial vertebrate and invertebrate assemblages exploit large carrion accumulations generated by mass mortality events. Here, we investigated the composition and temporal dynamics of vertebrate and invertebrate assemblages associated with fish carrion from mass mortality events to evaluate how energy is transferred across the aquatic–terrestrial interface. We monitored 20 piles of common carp ( Cyprinus carpio ) carcasses (mean biomass 110 ± 17.7 kg per pile) generated during management‐related fish mass mortality events in a Mediterranean wetland (Spain) between 2020 and 2024. Vertebrate activity was recorded using camera traps throughout a 35‐day decomposition period, while invertebrate assemblages were surveyed repeatedly using standardised visual surveys. We quantified the occurrence, abundance, and carcass‐use time of vertebrate primary consumers (those feeding directly on carcass tissues) and secondary consumers (those feeding on carcass‐associated invertebrates), the occurrence and abundance of carcass‐associated invertebrates, and temporal changes in the composition of both vertebrate and invertebrate assemblages. A total of 35 vertebrate species and 20 invertebrate groups associated with carcass piles were identified. Resource consumption appeared largely influenced by invertebrate assemblages, mainly Diptera and Dermestidae larvae, and these patterns were associated with the composition of carcass‐associated vertebrate assemblages, which included principally species feeding on the invertebrates present on the carcasses. Vertebrate use of carcasses followed a temporal pattern that seemed to correspond with changes in invertebrate availability during decomposition, resulting in a gradual turnover in vertebrate assemblage composition over time. Together, these results suggest that fish mass mortality events can function as dynamic trophic hotspots in wetland ecosystems, where invertebrates may play an important role in mediating energy transfer across the aquatic‐terrestrial interface. By jointly examining vertebrate and invertebrate assemblages, this study provides new insights into the ecological functioning of large carrion pulses at aquatic–terrestrial interfaces. As mass mortality events are expected to become increasingly frequent under global change, understanding these indirect trophic pathways is essential for predicting their consequences for food‐web dynamics, biodiversity conservation, and ecosystem functioning.