The influential physico-chemical parameters on the spatial and temporal distribution of oligochateas (
Limnodrilus
sp.) at the polluted downstream of LangatRiver were studied in comparison to the unpolluted upstream for 10-months sampling from March 1998 to February 1999. Based on the correlation analysis (CA) and multiple stepwise regression analysis (SRA), the distribution, abundance and density of
Limnodrilus sp. were almost consistent during the ten time samplings from April 1998 to February 1999. Based on CA, the density and distribution of
Limnodrilus sp. correlated negatively with the pH and dissolved oxygen (DO) while positively correlated with conductivity, biological oxygen demand (BOD), NO3, NH3, total suspended solids (TSS), chemical oxygen demand (COD) and dissolved concentrations of Cu and Zn. Based on SRA, most of the above parameters are selected as influential factors in affecting the distribution and presence of
Limnodrilus sp. on the tropical river. This indicated that the
Limnodrilus sp. is a pollutant resistant worm since they can survive in the poor water quality ecosystem. These results based on CA and SRA signified the resistance and tolerance of
Limnodrilus sp. survived at the polluted ecosystem of the tropical river. Hence,
Limnodrilus sp. is a good bioindicator of polluted rivers in the tropical ecoregion.
