Distribution of seagrasses, and their fish and penaeid prawn communities, in Cairns Harbour, a tropical estuary, northern Queensland, Australia

Zostera capricorni was the most common seagrass species and had the greatest biomass at 79 g m -2 dry weight of stems and leaves and 180 g m -2 dry weight of roots and rhizomes. The maximum shoot density found was 4798 shoots m -2 of Halodule pinifolia, the second most common species. Seagrasses were found only between 0.5-5.0 m below mean sea level. Zostera capricorni was found at the shallowest depths, H. pinifolia at the deepest depths. Twenty species of penaeid prawns, nine of which are marketed commercially, were samples from seagrass beds. Abundances of prawns of commercial species were significantly greater on seagrass-covered substrata than on nonvegetated substrata. Mostly small or juvenile fish, representing 134 taxa, were sampled from seagrasses in Cairns Harbour. The most numerous fish species were a goby Yongeichthys criniger, and a pony fish Leiognathus splendens. Density of fish on the seagrass beds was 8809 fish ha -1. -from Authors