Abstract

  The effect of sediment-borne and released chemicals on the phytoplankton and bacterioplankton communities of a clay-turbid and shallow lake was examined. Water and sediments from the lake were collected at two sites. One site near the source of pollution input (Eastern Region) and the second site 40 km from the pollution input (Central Region). The Elutriate Test was used to find the impact of sediment-borne substances. Elutriation of the water for the bioassays was done under aerobic and anaerobic conditions. Two sources of phytoplankton and bacterioplankton were used. One was the native organisms for each sampling site, the other was from the opposite sampling site. The phytoplankton bioassays showed inhibition of growth with increasing concentration of sediments regardless of source of sediments or phytoplankton. The bacterial bioassays showed, in most cases, stimulation of 14C-glucose uptake with the addition of sediments. Bacteria from the more polluted region when grown in less polluted region elutriate did not show any significant change in glucose uptake. When less polluted region bacteria were grown in more polluted region elutriate they showed a highly significant stimulation in uptake.

Keywords: sediment-borne nutrients, sediment-borne toxicants, elutriate test, bacterioplankton, phytoplankton