The effect of sea brine and bittern on survival and growth of mangrove Avicennia marina (Dicotyledones: Avicenniaceae)

The effect of 25.5degreesB'e brine and 28.5degreesB'e bittern prepared from 3.5degreesB'e seawater was studied on the juvenile plants of the mangrove Avicennia marina (Forsk.) Vierh under greenhouse conditions. The maximum in elongation growth and percentage increase in number of leaves in 5 % concentration of brine was 35.0 mm and 200 % respectively. However for 5 % bittern they were 33.0 mm and 160 % respectively. The 50 % concentrations of brine and bittern were growth inhibitory while 100 % concentration was lethal during 8 hours continuous exposure for 10 days. The highest growth of the Avicennia marina was observed when brine and bittern were diluted between 20 and 200 times. The undiluted and 50 % diluted brine and bittern were lethal and growth inhibitory, respectively. The leaves were the best indicator of the inhibitory or lethal effects on the plants. The 1 to 5 % brine promoted the growth of the leaves while other concentrations were inhibitory or lethal. However, the bittern in the range of 9 ml l(-1) and 1 to 50 % were growth inhibitory for leaves, while 100 % was lethal. The results indicate that discharge of brine and bittern in the marine environment, having semi diurnal tide cycle, will not be toxic or lethal to the plants.