HALOPHILA DECIPIENS OSTENFELD IN ESTUARIES OF SOUTHWESTERN AUSTRALIA

Glabrous Halophila decipiens Ostenfeld has been collected from four es tuaries in southwestern Australia. The plants form pure meadows or gro w with Halophila ovalis (R.Br.) Hook. f. and/or Zostera mucronata den Hartog on silty sand substratum, in channels near the mouths of the Sw an and Blackwood Rivers, and small patches of this species also occur adjacent to Z. mucronata and H. ovalis meadows near the mouth of Oyste r Harbour in Albany. Preliminary field observations at Hardy Inlet of the Blackwood River indicate that the seeds germinate in austral summe r, the plants grow through summer and set fruit and seed in autumn. To tal dry weight of biomass was 92.8 g m(-2) at the time of maximum biom ass in April, there were 6700 fruits m(-2) and 26.4 seeds per fruit, r esulting in an estimated 176 880 seeds m(-2) in the H. decipiens meado w in Hardy Inlet.