Notes on the biology and growth of Munida intermedia (Anomura: Galatheidae) in the western Pomo pit (Adriatic Sea)

Abstract

The squat-lobster Munida intermedia is very common over the muddy bottoms (depth 200–256 m) of the western Pomo pit (Central Adriatic). Density estimates, obtained from a short underwater television survey, ranged from 0.2 to 0.6 individuals/m2. Scientific trawling carried out in the years 1993–1994 with a small mesh net, yielded large catches of M. intermedia, and made possible the study of some aspects of its life history. M. intermedia is a gonochoric species that spawns once per year. Adult females have ripe ovaries in autumn and become ovigerous in winter. No ovigerous female was found after February. The smallest ovigerous female measured 8.5 mm carapace length, and the largest 23 mm. Fecundity is related to size and ranges between 870 and 5300 new-laid eggs per female. The reproductive season is well defined (from October to February), with a single spawning per year. Therefore, modal components in the length frequency distributions were identified with year classes and the mean lengths at age obtained were used to compute the parameters of the growth equation separately for the two sexes. The average life-span of M. intermedia probably does not exceed four years and males reach a slightly larger size than females (maximum carapace length: 25 mm males, 23 mm females). Sexual maturity in both sexes is reached at the end of the first year of life. A high percentage of specimens (males 9%, females 22%) had external evidence of infestation by Rhizocephala and representatives of three genera were recorded. Specimens as small as 7.5 mm carapace length were found parasitized and the highest frequencies of parasites were observed in the size range 10–14 mm.