Do Munida gregaria and M. subrugosa share the same feeding habit?

PATRICIA PEREZBARROS,; ROMERO, MC; CALCAGNO JAVIER,; GUSTAVO ALEJANDRO LOVRICH

La Serena – Coquimbo, Chile

Congreso; The Crustacean Society Mid- Year Meeting; 2007

The Crustacean Society y la Universidad Católica del Norte.

Munida gregaria and M. subrugosa are two very closely related sympatric morphospecies of squat lobsters. Among their morphologic differences, the distinct shapes of the dactylus and propodus of the third maxillipeds may be related to different feeding habits. We hypothesized that M. gregaria, characterized by having wide maxillipeds would be a deposit feeder, while M. subrugosa with more slender maxillipeds, a predator. A total of 91 adult Munida gregaria and 88 M. subrugosa were caught in the Beagle Channel during November 2004. The organic matter (OM) present in each stomach was quantified, and the importance of different food components in the diet was estimated by calculating their frequency of occurrence (FO) and their relative abundance (RA). The quantity of OM was similar in both morphospecies (5.85 ±2.16 and 6.66 ±1.43 mgOM · gDM animal-1 for M. gregaria and M. subrugosa, respectively; Student´s t-test, p= 0.22). Both morphospecies fed mainly on crustaceans, small macroalgae, sediment and particulate organic matter (POM). Sediment and POM were found in almost all stomach contents analyzed (FO ≥ 97.5), and represented 59% and 56% of the stomach contents of Munida gregaria and M. subrugosa, respectively. The RAs of sediment (21.9 and 24.8% for M. gregaria and M. subrugosa, respectively) and POM (36.8 and 30.9% for M. gregaria and M. subrugosa, respectively) were similar in both morphospecies (Student´s t-test, p= 0.17 and p= 0.08 for sediment and POM, respectively). However, M. subrugosa consumed significantly more crustaceans than M. gregaria (34.5 and 13.9% for M. subrugosa and M. gregaria, respectively; Student´s t-test, p<< 0.01), and M. gregaria consumed significantly more algae than M. subrugosa (21.3 and 5.6% for M. gregaria and M. subrugosa, respectively; Student´s t-test, p<< 0.01). Notwithstanding these differences, both morphospecies are predators as well as deposit feeders.