Active habitat selection for sand by juvenile western king prawns, Melicertus latisulcatus (Kishinouye)

This paper presents the results of a series of habitat selection experiment s aimed at determining if juvenile Melicertus latisulcatus generally occur on intertidal sand- and mud-flats as a result of active selection of unvege tated areas, or due to extrinsic factors (e.g. differential predation). In the laboratory, juvenile M. latisulcatus showed a clear preference for habi tats containing sand irrespective of the presence or absence of predators. If sand was not available, artificial seagrass was chosen as a secondary pr eference but was avoided when sand alone was also present. Importantly, the combinations of habitats chosen for testing allowed us to determine that a rtificial seagrass provided a good surrogate for real seagrass, and that th e presence of potential food (epiphytes) did not appear to influence habita t selection. There was also no difference in the habitat selected between d ay and night, and only minor differences with prawn size. Thus, juvenile M. latisulcatus appear to have a hierarchy of mechanisms for avoiding predato rs, with burying in sand being the preferred option. If burying is not poss ible, then seagrass is used for shelter. Active habitat selection to avoid predation appears likely to play a substantial role in determining the dist ribution of these animals on unvegetated sand- and mud-flats. (C) 2001 Else vier Science B,V. All rights reserved.