Malacobdella arrokeana: Parasite or Commensal of the Giant Clam Panopea abbreviata?

ALFAYA, JOSÉ E. F. ; GALVÁN, DAVID E. ; MACHORDOM, ANNIE ; PENCHASZADEH, PABLO E. ; BIGATTI, GREGORIO

ZOOLOGICAL SCIENCE

ZOOLOGICAL SOC JAPAN

Año: 2015 vol. 32 p. 523 - 530

0289-0003

We examined trophic relationship between the nemertean Malacobdella arrokeana and its host, theedible geoduck Panopea abbreviata by studying the diets of both species by direct (stomach contents)and indirect methods (stable-isotope analysis of C and N). In addition to these methods, thefeeding behavior of M. arrokeana within the host and the morphology of its feeding organs wereexamined. The feeding behavior of M. arrokeana did not exhibit parasitic characteristics, and theproboscis morphology indicates it is unable to injure host tissues. Analysis of stomach contentsrevealed a diet consisting mainly of microalgae and diatoms. Panopea abbreviata and M. arrokeanashared similar trophic levels, presenting no differences in the spread of the isotopic niches andhigh overlap (SEAB overlapped 63%). Consistent with this, our results showed no differences inδ15N or δ13C values between the two species. The combination of direct and indirect approachesrevealed that M. arrokeana has a diet similar to that of its host, confirming a commensal relationship.