MANGROVES AS NURSERIES - SHRIMP POPULATIONS IN MANGROVE AND NON-MANGROVE HABITATS

A total of 4845 penaeids belonging to nine species-Metapenaeus anchist us, M. ensis, M. moyebi, M. philippinensis, Penaeus merguiensis, P. mo nodon, P. semisulcatus, P. latisulcatus and Metapenaeopsis palmensis-w ere collected by pocket seine monthly over 13 months from mangrove and non-mangrove sites in Guimaras, Philippines. The restricted distribut ion of the three dominant species-M. ensis and P. merguiensis to the b rackish water riverine mangrove, and M. anchistus to the high-salinity island mangrove and tidal flat-is probably related to different salin ity and substrate preferences. Abundance and size composition of the m ajor species suggest a strong nursery role for the riverine mangrove ( high juvenile densities, relatively small sizes year-round), limited n ursery use of the island mangrove (fewer shrimps, larger size ranges, presence of maturing females) and a non-nursery use (e.g. foraging) in the tidal flat. Penaeid recruitment to the river had two peaks in Nov ember and May when the average salinity was similar to 20 (Practical S alinity Scale) and water temperatures were high (30-31 degrees C). The spatio-temporal pattern of penaeid species in Guimaras shows partitio ning across habitats and seasonal recruitment influenced by physical a nd biological factors. (C) 1998 Academic Press Limited.