Author(s): UG Abhijna and A Biju Kumar

Abstract: Multimetric index of index of biotic integrity using fish community was developed for the first time in Indian lake using seven candidate fish metrics such as native species richness, native family richness, benthic species richness, water column species richness, % non-native individuals, % tolerant individuals and % herbivores were applied in addition to five original metrics such as intolerant species richness, % omnivores individuals, % top carnivore individuals, total number of individuals and % individuals with anomalies. Tolerant species and non-native individuals were abundantly recorded at Veli-Akkulam Lake mainly at downstream sites where the water quality was highly degraded which is clearly reflected in water quality parameters such as BOD, COD, free Carbon-dioxide, phosphate, nitrite values and low levels of DO in water. Both traditional (5-3-1) and continuous IBI scores (0-10) examined were of similar pattern revealing maximum integrity at reference site with good water quality conditions. Modified score of fish biotic index decreased at both upstream and downstream sites of Veli-Akkulam Lake. But the score recorded at Vellayani Lake was higher than Veli-Akkulam Lake which was taken as the reference site which is far from the impact of major effluents sources of this ecoregion.

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