Impact of Water Pollution on The Ecology And Biology of Utricularia L. in Rajshahi

Abstract

The impact of water pollution on the ecology and biology of Utricularia L. have been studied in Rajshahi from July 1999 to June 2001. During the period of study 24 physico-chemical parameter of water and measurements of chemical nature of bottom soil of seven Utricularia habitats and those of seven without Utricu/aria were studied. All sampling spots are located in greater Rajshahi and sampling was performed at weekly intervals. The impact of water pollution was studied by the help of Utricularia culture in 5 earthen aquaria. Statistical analysis has been made to establish the interrelationship between the physicochemical conditions of water and biological conditions of Utricularia. Utricu/aria aurea (With float), Utricularia aurea (Without float), Utricularia stellaris and Utricularia exoleata were found in Rajshahi and these species were used in this study. During the period of study the impacts of different physico-chemical conditions of water on Utricularia spp. were observed. The normal biological processes and prey capturing ability of Utricu/aria spp. are affected by water temperature and higher values of TSS. From this study, it was recorded that the Utricularia spp. are unable to survive for more than one month in the polluted water having high organic load. During the period of study, it was observed that when transparency of Utricularia habitats decreased from 25 cm, the chlorophyll content of Utricu/aria spp. also started to decrease. When TDS value crossed 200 mg/I level, Utricu/aria spp. started to die rapidly; chlorophyll and protein content have started to decrease with increase of the TDS values. Utricularia spp. exhibited high growth rates when the pH value ranged from 7.1 to 7.5. A level of DO content congenial for the normal growth and function is always above 3 mg/I in case of Utricularia spp. When Eh value decreases from 0.755 mv, the flowering and fruit setting of Utricu/aria spp. get gradually inhibited; prey capturing activity was also found to decrease and the protein content was also started to decrease. From this study, it was recorded that when BODs value started to increase from 1.8 mg/I, the Utricularia spp. started showing a decrease in their growth. Utricularia spp. could not be grown in the water when COD value was higher than 7 mg/I and also started to die within seven days after releasing Utricularia spp. in the culture waters with high COD values. Utricularia spp. could not grow when conductivity value was increased from 220 μ-ohms/cm; chlorophyll and protein content of Utricularia spp. were started to decrease when the electric conductivity started to increase from 180 μ-ohm/cm. When chloride value started to increase from 50 mg/I upwards, Utricularia spp. begins to show reduction in their growth and started to decompose within 15-20 days when chloride value goes above 60 mg/I. During the period of study, it was observed that Utricularia spp. can not grow in hard water (>150 mg/I hardness). When total hardness level started to increase from 150 mg/I, the growth of Utricularia spp. started to decrease; chlorophyll and protein content also started to decrease; in this situation after one month Utricularia spp. started to die and decompose eventually. Attempt was made to grow Utricularia spp. in vary hard water (>180 mg/I hardness) but could not succeed and within 10-13 days Utricularia spp. started to die. It was also observed that immature flower and fruit could not mature in hard water and flower could not open. When calcium hardness content reached to 165 mg/I, the Utricularia plants started to die and get decomposed eventually. During the period of study, it was recorded that, the Utricularia spp. could not carryout its normal biological activities, such as flowering, fruit setting, photosynthesis, trapping of prey and growth, when phosphate content of waler was started lo rise above 0.112 mg/I and within 10-12 days, the leaf colour is changed into radish brown, immature fruits turned black, chlorophyll and protein content are reduced to half and immature flower failed to open and its colour turned black; within 18-20 days the whole plant starts to die and decomposed eventually. From this study, it was observed that the growth and biological activities of Utricularia spp. were affected by the ammonium nitrogen. When ammonium nitrogen values started to increase from 0.05 mg/I, the biological activities of Utricu/aria spp. also started to decrease. When ammonium nitrogen begins to go above 0.10 mg/I, then within 5-7 days all parts of Utricu/aria spp. start to die and get decomposed. During the period of study, it was observed that the growth and biological activity of Utricularia spp. were affected by higher total sulphide content. The biological activities of Utricu/aria spp. have started to retard gradually when total sulphide content begins to rise from 0.50 M mol 1·1. All parts of Utricularia plants start to die and get decomposed within 7 days when total sulphide content rises above 0.80 M mol 1·1. The present investigation reveals that the species of Utricularia fail to perform their normal biological activities in polluted water and showed some threshold limits of inactivation under certain physicochemical changes of the habitat water. Death and decomposition of the study plants ensue at certain values of such physico-chemical conditions.