Predation of the invasive Rapa Whelk, <i>Rapana venosa</i>, by the native Warty Crab, <i>Eriphia verrucosa</i>

Invasive species pose a significant threat to ecosystems, and biotic resistance plays a crucial role in mitigating this impact. In marine ecosystems, predation is the most effective form of biotic resistance against invasive species, making it essential to understand predator-prey interactions for effective management. In this study, we conducted two laboratory experiments to assess whether the native Warty Crab (Eriphia verrucosa) could serve as an effective predator of the invasive Rapa Whelk (Rapana venosa) in the Black Sea. Our findings demonstrate that Warty Crabs of all sizes can prey on a wide range of Rapa Whelk sizes. Notably, when smaller whelks were unavailable, crabs successfully consumed larger individuals, with the largest whelk consumed measuring 98.9 mm in shell length. We observed three distinct predation strategies employed by the crabs, with the frequency of each strategy depending on the crab's size rather than the whelk's size. These results suggest that Warty Crabs have the potential to act as natural biocontrol agents against Rapa Whelks, offering valuable insights for future management plans. However, the continued success of the Rapa Whelk in the Black Sea raises an important question: Why hasn't the Warty Crab effectively controlled the whelk population in the wild? Addressing this question through further research on habitat complexity, alternative prey availability, and environmental factors will be crucial for designing more effective conservation and management strategies.