Effects of Morphological Changes Induced by the Rhizocephalan Parasite Polyascus polygenea on Predation Risk of the Asian Shore Crab Hemigrapsus sanguineus
Parasites can strongly influence ecological communities by altering host traits. Rhizocephalans, parasitic barnacles within Cirripedia, are widespread in marine ecosystems and are well known for inducing reproductive castration in their hosts, especially inducing morphological feminization in male hosts. The rhizocephalan Polyascus polygenea modifies cheliped propodus length in the host crab Hemigrapsus sanguineus. To test whether rhizocephalan infection increases host predation risk through changes in cheliped propodus length, we conducted field tethering experiments comparing parasitized and unparasitized individuals. P. polygenea infection did not directly increase the probability of predation in either sex. However, structural equation modeling revealed that in parasitized males, reduced cheliped length indirectly elevated predation risk. In females, parasitism reduced carapace width, which subsequently shortened cheliped length and increased vulnerability. These results demonstrate that P. polygenea infection indirectly heightens predation risk through parasite-induced morphological changes.
Read the full article, here