Life history of the galatheid crab Munida subrugosa in subantarctic waters of the Beagle Channel, Argentina

Abstract

Galatheid crabs of the genus Munida are the most abundant decapods in coastal waters off Tierra del Fuego, including the Beagle Channel (55oS, 68oW). Other galatheids off New Zealand, the North Pacific, and Central America, have proved to be of potential commercial interest, but the only fishery currently exploited is that for Pleuroncodes monodon, off central Chile (ca. 35oS). Monthly benthic samples were taken in the Beagle Channel starting in November 1997 in order to investigate distribution, reproduction, and feeding habits of Munida subrugosa. Two galatheid species were found, M. subrugosa being significantly more abundant than M. gregaria. The reproductive cycle of Munida subrugosa started in June, and was reflected by the maximum size of oocytes, the maximum value of gonadosomatic index in both females and males, and by the proportion of ovigerous females. The embryonic development lasted 90-120 days. Fecundity (~10011,000 eggs) correlated with female size. Females attained their gonadal maturity size at ~11 mm carapace length (CL). Males reached morphometric maturity at ~24 mm CL, although males ~10 mm CL presented spermatophores. Munida subrugosa has two different feeding habits, as a predator (feeding on crustaceans and macroalgae) and/or as a deposit feeder (ingesting sediment, foraminiferans, diatoms, and particulate organic matter). The proportion of inorganic matter was higher at depths >40 m, suggesting that the condition of deposit feeder increases with depth.