POPULATION CHARACTERISTICS OF THE NEUSTONIC ISOPOD IDOTEA-METALLICA (CRUSTACEA, ISOPODA, IDOTEIDAE) IN THE WESTERN MEDITERRANEAN (JUNE 1993)

The population structure and reproductive condition of the neustonic i sopod Idotea metallica was determined from samples collected in June 1 993 during a plankton cruise off the Catalan coast (western Mediterran ean). Sexes were distinguishable fi om a size of around 4 mm total len gth. Both male and female size population structure were found to be p olymodal. Ovigerous females were found at sizes larger than 13 mm and a mean size at sexual maturity of 14.9 mm was estimated. Brood size va ried between 30 and 182 embryos per female and was positively correlat ed with female size.