Increasing occurrence of the bearded fireworm (Hermodice carunculata) poses a threat for small-scale fisheries in the central Mediterranean Sea

Abstract

Climate change is reshaping the distribution and abundance of marine species globally, with rising temperatures driving the spread of warm-water organisms. The Mediterranean Sea is recognized as a climate change hotspot where several warm water species are expanding, such as the bearded fireworm Hermodice carunculata, showing strong potential to become new native invaders. This trend carries important ecological and socio-economic implications, particularly for small-scale fisheries (SSF), a sector often overlooked despite its vital societal role. To investigate long-term ecological shifts, this study draws on Local Ecological Knowledge (LEK) to assess changes in H. carunculata occurrence, its perceived impact on SSF, and fishers' willingness to engage in mitigation activities. Structured interviews were conducted with 120 fishers in 12 coastal locations across Italy during 2023–2024. Results revealed a geographic gradient: high fireworm occurrence in the southeast, and rare or absent sightings in the northwest. Responses indicated a progressive rise in occurrence from 1990 to 2024, highlighting the species' role in the ongoing ‘meridionalization’ of the Mediterranean. Set nets were identified as the most impacted gear, followed by traps and bottom longlines. This impact appears linked to the benthic nature of both the species and these static fishing gears, which are particularly susceptible to scavenging by H. carunculata. In high-impact areas, fishers, especially younger ones, expressed a strong willingness to participate in collaborative mitigation initiatives, with particular emphasis on eradication strategies. These findings offer critical insights into species dynamics and support the development of ecosystem-based, adaptive management in a warming climate.