DAILY ACTIVITY PATTERNS OF THE MUD SHRIMP SOLENOCERA MEMBRANACEA (DECAPODA: PENAEOIDEA: SOLENOCERIDAE) IN THE WESTERN MEDITERRANEAN: A COMPARISON BY DEPTH AND SEASON

摘要

The diel catchability patterns of the western Mediterranean warm and temperate water mud shrimp Solenocera membranacea (Risso, 1816) were studied as a proxy of its behavioral activity in relation to depth and season. Animals were sampled with an epibenthic trawl during four continuous 24-hr cycles of trawl hauls made on the continental shelf (100-110 m) and slope (400-430 m) in October (autumn equinox) and June (summer solstice). Density estimates of animals present on the bottom at the time of the haul were computed from captures. Time series revealed marked rhythmic behavioral on-bottom activity. In both seasons, activity was nocturnal on the continental shelf. A less marked diurnal rhythm was present on the slope with emergence phased in the afternoon. Emergence patterns at both depths showed a regulation with seasonal variations in photoperiod length. Analysis of the catch size structure did not reveal significant differences between depths and seasons, indicating that behavioral performance is not affected by sexual maturity.