Evaluation of Mediterranean sponges as natural samplers for environmental DNA (eDNA)

<ns3:p> Marine sponges have emerged as effective natural samplers of environmental DNA (eDNA), offering a promising alternative for biodiversity monitoring. By filtering large volumes of seawater, sponges accumulate eDNA from surrounding communities, potentially enhancing species detection in marine environments where conventional water sampling is limited. In this study, we evaluated the eDNA recovery efficiency of seven Mediterranean sponge species to identify optimal candidates for biomonitoring. <ns3:italic>Axinella verrucosa</ns3:italic> outperformed other tested species, highlighting its potential for long-term biodiversity assessments. Our results align with previous findings that low microbial abundance (LMA) sponges recover more eDNA than high microbial abundance (HMA) species, reinforcing the need for targeted sponge selection in future studies. Detected fish taxa were all bottom dwelling, supporting the relevance of sponge eDNA for monitoring cryptic species and benthic habitats. As eDNA-based monitoring advances, sponge sampling offers a valuable complement to water eDNA surveys, particularly in habitats where conventional sampling is challenging. </ns3:p>