Effect of 2,6 dibromophenol; 2,4,6 tribromophenol and the extract of <i>Ptychodera flava</i> (Eshscholtz) [Hemichordate: Enteropneusta] on the eggs of sand crab <i>Emerita asiatica</i> (Milne Edwards)

Abstract

Laboratory experiments were performed to study the effect of natural extract of Ptychodera flava and authentic compounds (2,6 dibromophenol and 2,4,6 tribomophenol) on respiratory rate of various developmental stages of the eggs of the sand crab Emerita asiatica. Fresh extract stimulated increased respiratory rate in Stage I eggs, while aged extract had an inhibitory effect causing decreased respiratory rate. Comparitive studies using authentic compounds indicate the likely occurrence of 2,6 dibromophenol and 2,4,6 tribromophenol in the natural extract. The compound 2,4,6 tribromophenol also enhances the respiratory rate in Stage I eggs, while 2,6 dibromophenol generally depresses the respiratory rate of eggs at all the three stages. The functional significance of the extract in altering the community structure and organisation in the habitat of P. flava is discussed.