Effects of water hyacinth Eichhornia crassipes (Mart.) Solms-Laubach treatment with sodium chloride on aquatic biological communities of a semi-artificial system

Abstract

This study was conducted to evaluate the impacts on aquatic biological communities (plankton, macroinvertebrates) induced by the application of sodium chloride in control of water hyacinth Eichhorniacrassipes. For this purpose, an experimental device consisting of a pond containing hyacinth plants (2/3 of the surface) and a spraying system were used. Sea water of 24.68 g/ L NaCl was used to spray hyacinth plants for one day. Plankton (phytoplankton and zooplankton) were evaluated before the start of the test and every 5 days after application of the saline solution while benthic macroinvertebrates were only evaluated at the beginning and end of the experiment in areas covered and not covered by water hyacinth. Note that phytoplankton biomass was estimated by assaying chorophyll a. The results obtained show that in free water the concentration of chlorophyll a has increased from 0.02 to 0.32 mg/L; this rose from 0.01 to 0.23 mg / l in hyacinth water. The diversity and density of zooplankton decreased from 16 to 6 and from 85 to 42 individuals per liter respectively in free water and in hyacinth water. On the other hand, those of macroinvertebrates increased from 173 to 425 and from 418 to 999 respectively in free water and in hyacinth water.