Population Structures of Freshwater Fishes from Iligan River, Iligan City, Philippines

摘要

The population structure of freshwater fishes shapes the structure of a river system. Thenumber and kind of organisms, and the interactions among these organisms with eachother and with their environmeWe investigated a river in Iligan City where 3 areas have different levels of environmentalqualitydownstream Tubod ithe 238 fishes collected from 3 areas of the river, 27 species (3 unknown) were accountedfor. Sixteen (16) species (2 unknown) were documented in upstream Pugaan, 4 species inmidstridentified belongs to 8 families namely:Eleotridae, Gobiidae, Rhyacichthyidae,GobResults show that upstream Pugaan had the highest species composition (16 out of 27species) while midstream Palao had the lowest species composition (4 out of 27 species).Midstream Palao’s very few species composition and count maybe attributed to the factthat the river receives more anthropogenic municipal effluents contributed from thegrowing residents in the area aside from industrial effluent of an industry situated inmiddle part of the upstream vicinity. In downstream Tubod, higher number of speciescomposition (15 out of 27) exists. The current results which show differences in diversity,community structure and species assemblage of the fishes found in differentriver may indicate differences in aquatic habitats’ biotic and abiotic factors threatening theassemblage of the fishes within the range of spatial distributionof the fish populations are however needed to evaluatehabitats to be able to determine the specific factors that threatened their diversity andconservation.