A total of 53 species of juvenile fish were caught over a 2 yr study period in 2 mangroveudlined estuaries in Moreton Bay, eastern subtropical Australia. Comparing juvenile fish communitiesudamong mangrove forests, seagrass beds and mudflats identified significant differences in species rich-udness and abundances of juveniles. Seagrass communities comprised distinct species of resident andudnonresident fish species of little economic importance. Mangrove forests and mudflats had manyudshared species (but mangrove forests were dominated by smaller or younger juveniles in greater abun-uddances; Laegdsgaard unpubl. data). Mudflat habitats appear to be transition zones between juvenileudand adult habitats. Only 4 species were exclusive to seagrass whereas 27 species were exclusive to theudmangrove/mudflat habitat. Juveniles of 7 of the 10 commercially harvested fish species in Moreton Bayudwere found in greatest numbers in mangrove forests. Salinity, temperature and turbidity were similarudin all habitats so could not account for differences in habitat choice of juvenlle fish. Most juvenile fishudin mangroves during summer were nonresidents and species richness and abundance were highest inudsummer and lowest in winter There were significant differences among sites and years in the numbersudof species and individuals; however, the trends were similar and demonstrated clearly that mangroveudsites within Moreton Bay play a more important role and have greater potential as nursery habitatsudthan do adjacent habitats. Preferential selection of mangrove habitats by juvenile fish, particularlyudcommercial specles, indicates a need for conservation.
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